native vegetation and profitable perennials to ameliorate ...€¦ · increasing pest pressure on...

Native Vegetation and Profitable Perennials to Ameliorate Salinity, and Enhance Biodiversity, Beneficial Insects and Pest Control

A report for the Rural Industries Research and Development Corporation

By Peter D Taverner and Glenys M Wood

December 2006 RIRDC Publication No 06/129 RIRDC Project No SAR- 49A

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© 2006 Rural Industries Research and Development Corporation. All rights reserved. ISBN 1741513928 ISSN 1440-6845 Native Vegetation and profitable perennials to ameliorate salinity, and enhance biodiversity, beneficial insects and pest control Publication No. 06/129 Project No.SAR-49A. The information contained in this publication is intended for general use to assist public knowledge and discussion and to help improve the development of sustainable industries. The information should not be relied upon for the purpose of a particular matter. Specialist and/or appropriate legal advice should be obtained before any action or decision is taken on the basis of any material in this document. The Commonwealth of Australia, Rural Industries Research and Development Corporation, the authors or contributors do not assume liability of any kind whatsoever resulting from any person's use or reliance upon the content of this document. This publication is copyright. However, RIRDC encourages wide dissemination of its research, providing the Corporation is clearly acknowledged. For any other enquiries concerning reproduction, contact the Publications Manager on phone 02 6272 3186. Researcher Contact Details Glenys M Wood Research Officer SARDI Box 397 GPO Adelaide SA 2001 Phone: 08 83039660 Fax: 08 83039542 Email: [email protected]

Dr Peter Taverner Principal Investigator SARDI Box 397 GPO Adelaide SA 2001 Phone: 08 83039660 Fax: 08 83039542 Email: [email protected]

In submitting this report, the researcher has agreed to RIRDC publishing this material in its edited form. RIRDC Contact Details Rural Industries Research and Development Corporation Level 2, 15 National Circuit BARTON ACT 2600 PO Box 4776 KINGSTON ACT 2604 Phone: 02 6272 4819 Fax: 02 6272 5877 Email: [email protected]. Web: http://www.rirdc.gov.au Published in December 2006 Printed on environmentally friendly paper by Canprint

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Foreword Increasing pest pressure on the Northern Adelaide Plains (NAP) remains a real threat to horticulture in the region. One of the major problems is Tomato Spotted wilt virus (TSWV) that is vectored by three introduced pest thrips Western Flower Thrips (WFT) Frankliniella occidentalis, tomato thrips F. schultzei and onion thrips Thrips tabaci. Pest and virus damage has cost the industry up to $20million a year in lost crops and overheads. This study was conducted to determine whether indigenous perennial native species are less suitable hosts of invertebrate pests, particularly of WFT, than common weeds, when grown near horticulture on the NAP. This report evaluates invertebrate populations on different native plants and grasses for revegetation to replace weeds and suppress agricultural pest populations and disease on the NAP. Emphasis was placed on plant species that benefit Natural Resources Management (NRM), maintain populations of beneficial insects and have the potential to generate profit. Overall, the results suggest that a reduction in the key thrips species may be possible, but the replacement of weeds by native plants should not be left to chance. This study will assist landholders to make informed decisions about plant selection, which we collectively refer to as ‘revegetation by design’ and move towards improved integrated pest management (IPM) strategies. This project funded by Rural Industries Research and Development Corporation (RIRDC) was part of a larger program funded by Department of Transport and Regional Services Sustainable Regions Programme and Horticulture Australia Limited (HAL) with additional finance and in-kind provided by the Australian Government ENVIROFUND, City of Playford, Virginia Horticulture Centre and South Australian Research and Development Institute (SARDI). This report, an addition to RIRDC’s diverse range of over 1500 research publications, forms part of our Environment and Farm Management R&D program, which aims to support innovation in agriculture and the use of frontier technology to meet market demands for accredited sustainable production. Most of our publications are available for viewing, downloading or purchasing online through our website: • downloads at www.rirdc.gov.au/fullreports/index.html • purchases at www.rirdc.gov.au/eshop Peter O’Brien Managing Director Rural Industries Research and Development Corporation

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Acknowledgments Dr Nancy Schellhorn developed the original concepts, design and funding base for the project and guided the early stages as principal investigator. For taxonomy and field work, thanks to; Dr Richard Glatz, Mr Kym Perry, Mr Nathan Luke, Ms Susan Ivory, Ms Nola Lucas, Ms Karen Geyer and Dr Claire Stephens. In addition, to Ms Julie Lindner and Ms Judy Bellati who also made countless pollen Scanning Electron Microscopy images and Ms Sue Gerhig for data analysis. Thanks to Ms Dijana Jevremov, the project Communication Officer and consultants Mr Bill Doyle, Botanist and revegetation provider and Mr John Stafford, (Revegetation Services) for advice and direct seeding of native grasses. We would also like to thank members of the Revegetation by Design management team Tony Burfield, Domenic Cavallaro, Bill Doyle, John Stafford, Van Le, Kylie Robinson, Glenn Christie and Mike Redmond for their considerable knowledge, advice and practical support towards the delivery of the project on the Northern Adelaide Plains. Thank you also to the vegetable growers and their families Mr Thien Vu and Mr Minh Phan who kindly hosted two of our on-farm trials in Virginia. To the City of Playford revegetation staff, Green Corps and the Youth Conservation Council for planting native plants “ by design”. Special thanks go to Lawrence Mound and Murray Fletcher for their valued advice. To the SARDI Entomology Unit staff for a diverse range of support and to the team at Adelaide Microscopy, The University of Adelaide for SEM advice and assistance.

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Contents Foreword...............................................................................................................................iii Acknowledgments................................................................................................................iv Executive summary............................................................................................................viii 1. Introduction .....................................................................................................................10 2. Abundance and diversity of pest and beneficial invertebrates on weeds and remnant native vegetation on the Northern Adelaide Plains, South Australia..............12

Introduction...................................................................................................................................... 12 Materials and Methods..................................................................................................................... 12

Study Area ................................................................................................................................... 12 Sampling...................................................................................................................................... 13 Statistical analysis........................................................................................................................ 14

Results.............................................................................................................................................. 15 Method 1...................................................................................................................................... 15 Pests ............................................................................................................................................. 15 Beneficials ................................................................................................................................... 18 Sub sample for evaluation of parasitic wasps.............................................................................. 18

Discussion ........................................................................................................................................ 20 Pest thrips .................................................................................................................................... 20 Beneficials ................................................................................................................................... 21

3.1. Survey of invertebrates on brassica weeds, native plants and native grasses in the Virginia horticulture area on the Northern Adelaide Plains......................................22

Introduction...................................................................................................................................... 22 Materials and methods ..................................................................................................................... 22

Study area .................................................................................................................................... 22 Sampling...................................................................................................................................... 24 Analysis ....................................................................................................................................... 24

Results.............................................................................................................................................. 25 Overall invertebrate pest abundance............................................................................................ 25 Pest thrips .................................................................................................................................... 26 Beneficial Invertebrates ............................................................................................................... 27 Non-Target invertebrates ............................................................................................................. 27 Invertebrate Composition ............................................................................................................ 28 NON-TARGET ........................................................................................................................... 31

Discussion ........................................................................................................................................ 32 3.2. Invertebrate abundance and composition on selected native perennial plants and brassica weed plots on the Northern Adelaide Plains.....................................................33

Introduction...................................................................................................................................... 33 Materials and Methods..................................................................................................................... 33 Results.............................................................................................................................................. 34

A comparison of invertebrate guilds on native plants species and brassica weeds ..................... 34 A comparison of key pest thrips on native perennial plant species and weeds ........................... 39

Discussion ........................................................................................................................................ 39 3.3. Invertebrate abundance and composition on selected native grasses and brassica weed plots on the Northern Adelaide Plains ....................................................................41

Introduction...................................................................................................................................... 41 Materials and Methods..................................................................................................................... 41 Results.............................................................................................................................................. 42

A comparison of invertebrate guilds on four native grass species and brassica weeds for the spring period. ............................................................................................................................... 42

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A comparison of pest thrips on four native grass species and Brassica weeds for the spring period ........................................................................................................................................... 48

Discussion ........................................................................................................................................ 48 3.4. Summary.......................................................................................................................50 4. Characterisation of flowering of weeds and native plants with seed formation and management practices of profitable native plants on the Northern Adelaide Plains ...52

Introduction...................................................................................................................................... 52 Materials and methods ..................................................................................................................... 53

Sampling...................................................................................................................................... 53 Results and discussion ..................................................................................................................... 53

Flowering..................................................................................................................................... 53 Seed development and collection ................................................................................................ 57

5. Direct seeding trials of three native grasses Chloris truncata, Enneapogon nigricans and Austrodanthonia linkii (fulv) in a horticultural context on the Northern Adelaide Plains....................................................................................................................59


Sites and site preparation ............................................................................................................. 59 Equipment.................................................................................................................................... 60

Results.............................................................................................................................................. 60 Discussion ........................................................................................................................................ 61

6. Pollen as a marker: using Scanning Electron Microscope (SEM) images to describe the movement of the native brown lacewing Micromus tasmaniae on the Northern Adelaide Plains....................................................................................................................63


Sampling Sites ............................................................................................................................. 63 Examination of SEM samples ..................................................................................................... 64 Local lacewing movement from host plant (GMP) ..................................................................... 64

Results.............................................................................................................................................. 64 Discussion ........................................................................................................................................ 67

7. Information Days and Surveys held at the Greenhouse Demonstration Site of Virginia .................................................................................................................................69


Information Days Promotion ....................................................................................................... 69 Information Days Format ............................................................................................................ 70 Project Evaluation........................................................................................................................ 70

Survey Results ................................................................................................................................. 70 Information Day 1, April 2004 .................................................................................................... 70 Information Day 2, October 2005................................................................................................ 71 Information Day 3, March 31 2006 ............................................................................................. 71 Accumulated Result..................................................................................................................... 72

Discussion ........................................................................................................................................ 72 Questionnaire ................................................................................................................................... 73

8. Implications and Recommendations.............................................................................75 9. References .......................................................................................................................76 10. Appendices ....................................................................................................................78

Appendix 1. Plates 1 - 6 ................................................................................................................... 79 PLATE 1 – CHENOPODIACEAE ............................................................................................. 79 PLATE 2 – CHENOPODIACEAE ............................................................................................. 80 PLATE 3 – MIMOSACEAE AND MYRTACEAE.................................................................... 81 PLATE 4 – POACEAE AND GOODENIACEAE ..................................................................... 82

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PLATE 5 – MYOPORACEAE, BRASSICACEAE, OXALIDACEAE, BORAGINACEAE AND SOLANACEAE................................................................................................................. 83 PLATE 6 – UMBELLIFERAE, AZIOACEAE, MALVACEAE AND ASTERACEAE ........... 84

Appendix 2. Information Transfer ................................................................................................... 85 Scientific publications ................................................................................................................. 85 Conference Papers and Posters.................................................................................................... 85 Information Days......................................................................................................................... 85 Presentations................................................................................................................................ 86 Media ........................................................................................................................................... 87 Popular Articles ........................................................................................................................... 87 Signage and Web site .................................................................................................................. 87

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Executive summary What the report is about Pest and virus damage has cost the Northern Adelaide Plains (NAP) horticultural industry up to $20 million a year in lost crops and overheads. This study was conducted to determine whether indigenous perennial native species are less suitable hosts of invertebrate pests, particularly of Western Flower Thrips (WFT), than common weeds, when grown near horticulture on the NAP. This report evaluates invertebrate populations on different native plants and grasses for revegetation to replace weeds and suppress agricultural pest populations and disease on the NAP. Emphasis was placed on plant species that benefit Natural Resources Management (NRM), maintain populations of beneficial insects and have the potential to generate profit. Background A key challenge for natural resource management in horticulture is the integration of native vegetation into commercial practices. Revegetation programs have not been well received in horticultural producing areas because of perceptions that native plants host crop diseases and harbour pests. On the NAP, weeds are recognised as a major issue because they harbour WFT, Frankliniella occidentalis, which are efficient vectors of Tomato Spotted Wilt Virus (TSWV). Current strategies to control WFT, including ‘bare earth’ buffers around crops and high chemical use, are expensive and not sustainable. An alternative would be to replace weeds with native plants that can be shown not to host TSWV or harbour WFT. In addition, perennial native plants may support integrated pest management (IPM) strategies by providing a stable refuge for natural enemies near ephemeral horticultural crops. However, it is well recognised that for revegetation to occur, there needs to be an incentive for landholders. Perennial native plants that generate profit are most likely to present a reasonable prospect to engage growers to revegetate threatened land that is under commercial production. For commercial growers to be confident in their revegetation choices, the relative risks and benefits that weeds and/or native plants could pose to their crops needs to be understood and addressed. Objectives This project aimed to provide a framework of information for those involved with the horticulture industry and natural resources management to make informed decisions about selecting native vegetation to reduce the pest and disease pressure on crops on the NAP. In this study, the potential for indigenous native plants and grasses to either host pests or beneficial insects was examined. Methods and Results Initially, information on the abundance and diversity of pest and beneficial insects was collected through surveys of weeds and remnant native vegetation. Following surveys, selected indigenous plants (Maireana brevifolia, Atriplex semibaccata and Rhagodia parabolica) and grass (Themeda triandra, Chloris truncata, Enneapogon nigricans and Danthonia linkii) plots were established near commercial glasshouses. The invertebrate fauna from these plots were regularly collected and categorised into functional guilds. The prevalent pest and beneficial taxa on the native plants and grasses were compared with each other, and with nearby brassica weed plots. Survey results indicate that the abundance of WFT on brassica weeds was up to 300 times higher than on native plants, and up to 160 times higher than the native grasses. The native plants and grasses also recorded far fewer tomato and onion thrips, which can also vector TSWV. A reduction in TSWV-vectoring thrips would be advantageous, but it is unclear whether some other invertebrates may in time emerge as new pest problems. The most abundant invertebrates likely to become pests on native plants and grasses were leafhoppers and aphids, respectively. However, the common weeds in the area would also harbour significant populations of these potential pests. Regardless, the saltbushes, and, in particular, A. semibaccata, require taxonomic evaluation to determine the disease vectoring capacity

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of leafhoppers present. Likewise, host preference testing of important pest aphids, such as lettuce aphid, on native plants and grasses should be considered. Native plants and grasses harbour more diverse beneficial invertebrates and fewer WFT, than weeds. Native plants and grasses have the potential to support a range of natural enemies, and can provide a stable refuge area near cropping activities. In addition, there is a substantial group of invertebrates that represent species of unknown function. Many of the species will not impact on nearby horticultural crops, but some beneficial or pest species may emerge with larger plantings and in subsequent seasons. Implications and recommendations Overall, the results suggest that using selected native plants, a reduction in the key thrips species that host TSWV is possible. However, it would also appear that the native species chosen in these trials have a range of agronomic and host specificity characteristics that can influence IPM outcomes; in both beneficial and potentially undesirable ways. This confirms the concept of informed and deliberate plant choice, which we collectively refer to as ‘revegetation by design’. Considerable knowledge and insights have been gained, but to make improved and reliable recommendations further investigations are required. Areas of particular interest include the beneficial suite of invertebrates, in particular the parasitic wasps associated with control of thrips, predatory Erythraed mites found on native grasses, and brown lacewings warrant investigation for potential in IPM strategies to control lettuce aphid. Areas for further study include, evaluation of the taxonomy and host preference of whitefly found on Rhagodia parabolica, the diversity of coccinellid species on the native grasses and Rhagodia parabolica and Chirothrips manicatus as alternative hosts for parasitic wasps associated with the control of pest thrips.

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1. Introduction Insect pests are a genuine threat to the future viability of horticulture on the Northern Adelaide Plains (NAP). In 1995, the arrival of the exotic Western Flower Thrips (WFT), a major vector of Tomato Spotted Wilt Virus (TSWV), into the Virginia horticulture region has resulted in estimated annual crop losses and management overheads in the vicinity of $25 million. The major issues are weeds that harbour thrips that vector TSWV and provide a source for early virus transmission to nearby crops. Current chemical and cultural insect pest control methods are unsustainable and not always effective. In addition, the NAP has a degraded natural landscape and there is a serious lack of commercial incentives to improve biodiversity in the area. An alternative is to consider ‘revegetation by design’ and replace weeds with deep-rooted perennial native plants that harbour few pests and diseases of horticulture and in some cases can provide profit. The benefits are reduction in topsoil loss, chemical use and cultural crop management overheads with improved biodiversity and long-term sustainability. Conservation biological control and habitat manipulation in agricultural area for pest suppression and sustainability are emerging fields globally (Duelli and Obrist 2003). However there is relatively little information available for native vegetation as a habitat for beneficial insects in Australian conditions (Silberbauer 2001; Silberbauer & Schellhorn 2002). Information is available for weeds as hosts for pests and disease in the northern hemisphere, however, references that detail pest or beneficial insects on Australian indigenous native plants are rare (Latham and Jones 1997). To establish whether native plants could be maintained around horticultural crops without harbouring pest thrips we planted individual native plant and grass species demonstration plots at three sites in Virginia on the NAP. The major site is at the Greenhouse Modernisation Project (GMP) with the remaining sites on two grower properties nearby. We have native plant species from the Myrtaceae, Chenopodiaceae and Mimosaceae and native grasses across these three sites. The species plots have been established adjacent to horticultural for demonstration and to survey these plants for the presence of pest and beneficial arthropods. The broad objective of this project is to change the perceptions and behaviours of the community towards weeds, native vegetation and maintenance of natural resources. Our focus is to design revegetation options to replace weeds with native vegetation to reduce disease and pest pressure on the NAP. To achieve this objective research focussed on answering two major questions; (i) can native plants grow near crops without harbouring pest thrips? and (ii) are there differences in the capacity of individual native plant species to attract and support various insects? The aims of the research components are:

• to identify and sample remnant deep rooted native perennials and weeds on the NAP for the presence of key pests and beneficial arthropods

• to determine whether similar numbers of arthropods including pest and beneficial insects reside on remnant native vegetation and random weeds near to and far from horticultural crops

• examine a subset of samples for evaluation of parasitic wasp taxa with potential for biocontrol • characterise flowering and fruiting and management practices associated with perennial native

plants and weeds • establish demonstration trial plots of profitable native perennials adjacent to horticulture for

arthropod sampling to determine insect presence, abundance and timing • using SEM images, examine a subset of key beneficial insects for pollen as a marker of insect

movement within the landscape. Using this new information the project aimed to produce guidelines for growers, the community, industry and local government staff involved in revegetation to make informed decisions about

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selection of ‘best bet’ native plants for the design and establishment of native vegetation plantings that reduce pests and disease in horticulture, benefit Natural Resources Management and in some cases increase profitability.

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2. Abundance and diversity of pest and beneficial invertebrates on weeds and remnant native vegetation on the Northern Adelaide Plains, South Australia Introduction Revegetation programs have not progressed in the main horticulture-producing region of South Australia because of perceptions that native plants and weeds harbour pest thrips that vector Tomato Spotted Wilt Virus (TSWV). In addition, there is little consideration for biodiversity and its loss. Much of the native vegetation on the Northern Adelaide plains (NAP) such as the mallee woodlands in the Peachy Belt region was destroyed in the first eighty years since settlement and the remaining woodlands in the Angle Vale and Virginia area were probably cleared for market gardens after the war (Kraehenbuhl 1996). Current cultural weed management strategies aim to reduce thrips incidence by creating a bare-earth buffer around horticultural crops. This strategy requires significant chemical use and high labour costs. If some native plants that do not harbour pest thrips can be identified then these plants may be suitable to create a natural buffer around horticultural crops. The abundance of key pest thrips and the identity and distribution of natural enemies on weeds and native vegetation on the NAP has not been compared. In addition, the role that native vegetation plays in harbouring parasitic wasps and their hosts is not well understood. This study aimed to (i) determine whether similar numbers of invertebrates including pest and beneficial insects reside on remnant native vegetation and random weeds near to and far from horticultural crops; (ii) examine a sub set of samples for evaluation of parasitic wasp taxa with potential for biocontrol. Materials and Methods Study Area Arthropods were sampled on weeds and native plants fortnightly between March 2003 and 2004 on the Northern Adelaide Plains (NAP). The same groups of perennial plants were visited at 28 sites falling within the horticultural region surrounding Virginia and 16 regional sites amongst mixed grazing and cereal cropping within a 25 km radius adjacent to the horticultural region. The horticulture region is now a combination of urban areas and diverse horticultural activities such as field and covered vegetable crops (eg. potatoes, carrots, cabbages, onions, celery, tomatoes, capsicums, lettuce, and cucumbers), ornamental plants (nurseries and cut flowers), nuts (almonds), vines and olives. To determine the species composition and distribution of pest and beneficial insects, 19 weed species (Table 2.1) and 15 native plant species (Table 2.2) were sampled. Ephemeral weeds were located by driving around the NAP for two days per fortnight searching for plants with flowers visible from the roadside or at the native vegetation sampling sites. The indigenous native species from the Chenopodiaceae were single species or in mixed stands planted for seed orchards or land reclamation. Endemic native species from the Myrtaceae and Acacia were roadside remnant vegetation, Acacia baileyana and the eucalypts were part of the Laidlaw Plantation situated at the Waite Campus of the University of Adelaide. Annual weed species were found in mixed stands making sampling of single species suites problematic.

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Table 2.1. Weed species sampled between March 2003 and 2004 on the Northern Adelaide Plains

Family Species Common name Azioaceae Galenia pubescens(Eckl.&Zeyh.) Druce Blanket weed Asteraceae

Arctothea calendula(L.) Levyns Sonchus oleraceus (L.) Cirsium vulgare (Savi.) Ten

Cape Weed Common sow thistle Scotch thistle

Brassicaceae

Diplotaxis tenuiufolia (L.) DC Raphanus raphanistrum L. Rapistrum rugosum L. Sisymbrium orientale L.

Sand Rocket Wild radish Giant mustard Indian hedge mustard

Boraginaceae Echium plantagenum L. Patterson’s curse Chenopodiaceae Chenopodium album L. Fat hen Malvaceae Malva parviflora L. Marshmallow Oxalidaceae Oxalis pes caprae L. Soursob Polygonaceae Polygonum aviculare L. Wire weed Portulacaceae Portulaca oleraceae L. Portulaca weed Solanum

Solanum nigrum L. Solanum elaeagnifolium Cav.

Black nightshade Silverleaf nightshade

Umbelliferae Foeniculum vulgare Mill. Fennel Urticaceae Urtica urens Stinging nettle Zygophyllaceae Tribulus terrestris L. Caltrop

Table 2.2. Native plants species sampled between March 2003 and 2004 on the Northern Adelaide Plains and the Waite Campus of the University of Adelaide

Family Species Common name Chenopodiaceae

Atriplex semibaccata(R.Br. ) Atriplex suberecta(I.Verd) Atriplex paludosa(R.Br. ) Rhagodia parabolica(R.Br. ) Rhagodia crassifolia(R.Br. ) Enchylaena tomentose(R.Br. ) Maireana brevifolia(R.Br. )Paul G. Wilson)

Creeping saltbush Lagoon saltbush Marsh saltbush Mealy saltbush Scented saltbush Ruby saltbush Small leafed bluebush

Mimosaceae

Acacia victoriae (Benth.) Acacia baileyana/purpurea(F. Muell)

Elegant wattle Cootamundra wattle

Myrtaceae

Baeckea behrii(Schldl.)F.Muell. Kunzea pomifera(F. Muell) Eucalyptus tetragona Eucalyptus gillii

Silver broom Muntries Tallerack Curly Mallee

Sampling Sampling from weeds and native plants was conducted within 10 metres or greater than 100 metres from horticultural crops using two methods. Method 1 Foliage associated arthropods were sampled using a Dvac vacuum sampler (21 cc blower/ vac) with cone shaped voile and calico bags (23 cm diameter, 36 cm long tapering to a point) fitted to the end of the suction tube. To standardise sampling, the foliage of different plants were sampled for different times in an attempt to account for the large differences leaf area among the species. The vacuum was run over the total foliage area of the native Chenopodiaceae of five individual plants for five seconds each. Five individual trees, Acacia victoriae, A. baileyana, Eucalyptus gilli and E. tetragona were vacuumed for 10 seconds each. For large enough single species stands of weeds, the entire area of was vacuumed for 20 seconds. Arthropods were removed from the samples, and pest and beneficial invertebrates were identified as adult or juvenile and classified to family and where possible to species. The remaining insects were sorted to ‘morphospecies’ and recorded for each sample. ‘Morphospecies', or recognisable taxonomic

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units, are taxa readily identified by morphological differences distinct to individuals (Oliver & Beattie 1996). Representative ‘morphospecies’ were curated, photographed and recorded in a database. All morphospecies were assigned to a functional group based on biology. Morphospecies from a subset of Dvac samples from six plant genera were used for evaluation of parasitic wasp taxa: three endemic native and one weedy species from the Chenopodiaceae, Atriplex semibaccata, Maireana brevifolia Rhagodia parabolica, and Chenopodium album, plus an endemic native species from the Myrtaceae, Baekea behri and several weedy species suites in the family Brassicaceae. All plants occurred within 100 m of agricultural production (see Stephens et al. 2006). Voucher material has been deposited in the Waite Insect and Nematode Collection (WINC), University of Adelaide, South Australia. Method 2 Thrips are known to be attracted to flowers and can be extracted by exposing them to turpentine vapour. A standardised volume of floral units per plant species was collected into a ‘flower funnel’ sampling jar that combined aspects of the methods described by Lewis (1960) for thrips extraction and Gray and Schuh (1941) for aphid sampling (Fig. 2.1). A floral unit constituted an individual flower measuring greater than or equal to 1 cm diameter or a floret of multiple flowers that were less than 1 cm diameter. The sampling jar contained a fitted 70 ml plastic funnel within to contain blooms and the thrips were extracted using a few drops of turpentine on a cotton wick placed on top of the sample. After extraction the number of flower units per 70 ml funnel was counted and recorded for each species. Flower dissections performed on material after the extraction process indicated that this method was effective for extraction of thrips adults, larvae and other incidental visitors such as parasitic wasps, lepidopteran larvae and small beetles. Thrips were stored in 80% ethanol and four key pest thrips and predatory thrips species were identified using a dissecting microscope. Statistical analysis. The percentage of each morphospecies was calculated from presence / absence data recorded for all weed and native plant samples. The mean numbers of floral units were calculated for flower funnel samples for each plant species. Thrips data were averaged for all dates and all sampling sites and plants. The mean number of pest thrips per flower funnel sample was divided by the mean number of floral units to determine the number of thrips per 100 floral units for each of the pest thrips species. Log linear analysis was used to test for independence among plant types, distance to horticultural crops and presence of thrips. Odds ratios were used to determine the likelihood of finding thrips on plant species (SAS Institute 2001).

Figure 2.1. Flower funnel for extraction of thrips using turpentine wick

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Results Method 1 We analysed 55,006 individuals from 91samples representing 59 families (insects mites and spiders) on weeds and native plants and of these, 22 were phytophagus and 15 were insect predators. Native plants had a higher diversity of taxa than weeds. Pests Every weed sample had thrips (Thysanoptera) (native and/or pest species), and most samples of all weeds had aphids (Aphidae), leafhoppers (Cicadellidae), white flies (Aleyroididae) (with the exception of fennel) and mirids (Miridae) (Table 2.3). Most, but not all native plant species samples had thrips, aphids, leafhoppers, white flies and mirids (Table 2.4). Leafhoppers are not vectors of TSWV, but some species are implicated in vectoring other plant diseases so they were considered more closely. Leafhoppers were present as adults and nymphs on most of the Chenopodiaceae (saltbushes) and weeds, but were found less often on the Acacias and Myrtaceae. (Table 2.4, Fig.2.2). The leafhoppers identified were from the Subfamily Ulopinae (Tribe Cephalelini), Subfamily Austroagalloidinae, Subfamily Iassinae (Tribe Iassini), Subfamily Deltocephalinae (Tribes Deltocephalini, Macrostelini and Opsiini), Subfamily Eupelicinae (Tribe Paradorydiini) and Subfamily Typhlocybinae (Tribes Empoascini, Erythroneurini and Dikraneurini). Fig. 2.2. Percentage of samples where leafhopper (Cicadellidae) (adults and/or juveniles) were present for a range of native plants and brassica weeds

0

20

40

60

80

100

Atriplex paludosa(2)

A.sem

ibaccata(5)

A.sububerecta(3)

Enchylaena(23)

Maireana(23)

Rhagodia crassifolia(8)

R. parabolica(27)

Baeckea(23)

E. gilli(24)

E. tetragona(21)

Muntries(28)

Acacia victoreae(21)

brassica weed(13)

Plant species(n)

AdultsLarvae

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Table 2.3. Percentage of weed samples with pests (phytophagus), beneficial (predators and parasitoids) and non target invertebrates present on the NAP Brassicaceae Boraginaceae Chenopodiaceae Umbelliferae

Plant Species brassica mustard rocket turnip Salvation jane fathen fennel Function No samples =17 4 3 1 1 2 3 3

ACARINA 25% 33% 100% 100% 100% 33% Predator ARANEAE 50% 67% 100% 50% 67% 100%Predator

COLEOPTERA 50% 67% 0% 100% 50% 100% 33% Anthicidae Omnivore Carabidae Predator

Cerambicidae Phytophagus Chrysomelidae Polyphagous

Coccinellidae 100% 33% Predator Corylophidae

Cryptophagidae Fungivore Cucujoidea

Curculionidae 100% Polyphagous Dermestidae Phytophagus Lathridiidae 50% 67% 0% 100% 50% 67% 33%Fungivore Mordellidae Phytophagus

Nitidilidae Staphylinidae Predator

Tenebrionidae Detritivore COLLEMBOLA 25% 33% 50% DERMAPTERA

Forficulidae Omnivorous DIPTERA 100% 100% 100% 100% 100% 100% 67% Syrphidae Predator

Dolichopodidae Predator HEMIPTERA 100% 100% 100% 100% 100% 100% 100%

Aphididae 25% 33% 100% 100% 50% 33% 67%Phytophagus Aleyroididae 75% 100% 100% 100% 50% 100% Phytophagus

Anthocoridae 33% Phytophagus Cicadellidae 100% 100% 100% 100% 100% 100% 67%Phytophagus Coccoideae Phytophagus Fulgaroidea Phytophagus

Lygaeidae 50% 100% 100% 100% 100% 100% Phytophagus Meenoplidae Phytophagus

Membracidae Phytophagus Miridae 50% 100% 100% 100% 100% 100% 67%Phytophagus

Nabidae 25% 33% Predator Pentatomidae Predator

Phylliidae Psyllidae 50% 33% 33%

Rejuvidae 50% Predator Scutelleridae Phytophagus

Tingidae Phytophagus HYMENOPTERA 100% 100% 100% 100% 100% 100% 67%

Formicidae 25% 100% 100% 100% 67% 67%Polyphagous Ichneumonidae Parasitoid

Apidae 100% LEPIDOPTERA 100% 67% 100% 100% 100% 100%

Tortricidae PhytophagousPlutellidae 50% Phytophagous

MANTODEA Mantidae Predator

MYRIAPODA 100% 33% NEUROPTERA 33% 100% 33%

Hemerobiidae Predator Chrysopidae 33% 100% 33% Predator

Coniopterygidae Predator PSOCOPTERA 50% Omnivorous

THYSANOPTERA 100% 100% 100% 100% 100% 100% 100%Phytophagous

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Table 2.4. Percentage of native plant samples with pests (phytophagus), beneficial (predators and parasitoids) and non target invertebrates present on the NAP Mimosaceae Chenopodiaceae Myrtaceae Plant Species A bai A vict A palu A sem Enchyl Mairean R cras R para B beh E gil E tet Kunzea Function

No samples =80 3 7 6 10 5 7 6 6 8 5 11 6 ACARINA 33% 43% 50% 60% 60% 9% 20% 83% 38% 40% 55% 67% Predator ARANEAE 33% 57% 17% 50% 80% 11% 100% 67% 75% 100% 82% 100% Predator COLEOPTERA 100% 86% 33% 60% 40% 6% 60% 83% 25% 40% 55% 67% Anthicidae 10% Omnivore Carabidae 10% Predator Cerambicidae 17% Phytophagus Chrysomelidae 33% 43% 20% 20% Polyphagous Coccinellidae 29% 17% 20% 40% 40% 13% 17% Predator Corylophidae 10% 17% Cryptophagidae 10% Fungivore Cucujoidea 10% Curculionidae 100% 30% 0% 40% 67% 13% 9% Polyphagous Dermestidae 9% Phytophagus Lathridiidae 33% 29% 33% 60% 40% 6% 20% 50% 40% 9% 33% Fungivore Mordellidae 17% 9% Phytophagus Nitidilidae 17% Staphylinidae 10% Predator Tenebrionidae 20% Detritivore COLLEMBOLA 33% 29% 40% 20% 3% 50% 50% 20% 18% 67% DERMAPTERA 17% 33% Forficulidae 17% 33% Omnivorous DIPTERA 67% 100% 100% 80% 100% 14% 100% 100% 88% 100% 100% 100% Syrphidae 33% 10% Predator Dolichopodidae 17% 9% Predator Chironomodae 9% Predator HEMIPTERA 100% 100% 100% 100% 100% 14% 100% 100% 88% 100% 45% 100% Aphididae 29% 17% 40% 6% 80% 17% 20% 18% 67% Phytophagus Aleyroididae 71% 30% 80% 11% 80% 83% 55% 67% Phytophagus Cicadellidae 67% 43% 100% 80% 100% 14% 100% 100% 50% 80% 36% 67% Phytophagus Coccoideae 33% 29% 10% 20% 17% 38% 50% Phytophagus Fulgaroidea 13% 9% 50% Phytophagus Lygaeidae 14% 80% 60% 9% 20% 50% 33% Phytophagus Meenoplidae 10% Phytophagus Membracidae 33% Phytophagus Miridae 100% 57% 83% 70% 100% 14% 100% 100% 13% 100% 55% 33% Phytophagus Nabidae 14% 10% 40% 33% Predator Pentatomidae 10% 17% 13% Predator Psyllidae 100% 86% 33% 40% 20% 3% 40% 17% 50% 100% 64% 67% Rejuvidae 20% 9% 17% Predator Scutelleridae 10% 17% Phytophagus Tingidae 20% 25% 9% Phytophagus HYMENOPTERA 100% 86% 100% 100% 80% 11% 100% 100% 75% 80% 100% 100% Figitidae 18% Parasitoid Formicidae 67% 57% 100% 80% 20% 3% 100% 83% 50% 60% 18% 67% Polyphagous Ichneumonidae 10% 17% Parasitoid LEPIDOPTERA 67% 71% 67% 70% 60% 9% 80% 100% 75% 20% 27% 67% Phytophagus Tortricidae 33% Phytophagus MANTODEA 17% 17% Mantidae 17% 17% Predator MYRIAPODA 20% 18% 50% NEUROPTERA 100% 57% 17% 30% 20% 3% 40% 83% 25% 20% 27% 17% Hemerobiidae 33% 29% 20% 0% 20% 20% 27% 17% Predator Chrysopidae 33% 14% 83% Predator Coniopterygidae 33% 14% Predator ORTHOPTERA 20% 33% Eumastidae 20% Phytophagus PHASMATODEA Phylliidae 14% 10% 20% Phytophagus PSOCOPTERA 67% 29% 17% 30% 20% 40% 17% 38% 60% 45% Omnivorous THYSANOPTERA 67% 100% 67% 100% 100% 14% 100% 100% 100% 100% 82% 100% Phytophagus

18

Beneficials Samples collected from weeds included beneficial arthropod species, such as brown and green lacewings (Hemerobiidae, Chrysopidae respectively), parasitic wasps, nabids (Nabidae), and spiders (Araneae). Samples from the three native plant families also had a broad diversity of invertebrates including potential beneficial insects such as ladybird beetles, brown lacewings (Hemerobiidae), predatory Haplothrips (Phlaeothripideae), spiders (Araneae), mites (Araneae: Acarina) and parasitic wasps (mainly Eulophinae, Scelionidae and Trichogramatidae). Lacewings were examined more closely to consider their potential for biocontrol. All native plant genera sampled had adult and juvenile brown lacewings and they were present on three weed families (Brassicaceae, Boraginaceae and Azioaceae). Adults were found on most native species except Baeckea and larvae were mainly seen on plants in the Chenopodiaceae mainly on A. semibaccata (Fig. 2.3). Fig. 2.3. Percentage of samples where brown lacewings, Micromus tasmaniae (adults and/or juveniles) were present for a range of native plants and brassica weeds Sub sample for evaluation of parasitic wasps A total of 2106 wasps and bees from 25 families and 108 morphospecies were recorded. All plants supported a relatively high number of wasp morphospecies. The two weeds had the lowest species richness and lowest number of morphospecies recorded as singletons. The major wasp families were from the super family Chalcidoidea, in particular from the family Eulophidae. The Scelionidae and Trichogrammatidae were abundant but not diverse (Stephens et al. 2006). Method 2 We extracted 33,509 thrips from 581 samples. Of these, 23 species were identified, the vast majority consisting of the pest species, Frankliniella occidentalis, F. schultzei, Thrips tabaci and T. imaginis , present on most plant families. The predatory thrips, Haplothrips victoriensis, was found on most plant families except Mimosaceae, Polygonaceae and Portulacaceae. The remaining species detected were Desmothrips spp, Australothrips bicolor, Heliothrips haemorrhoidalis, Anaphothrips varii Moulten, A. sudanensis and A. cecile, Chirothrips manicatus, Limnothrips angulicoris, L. cerealium, Pesothrips kellyanus, Pseudanaphothrips achaetus, Tenothrips frici, Thrips australis, Nesothrips propinquus, Teuchothrips spp. and Baenothrips moundii.

02040

6080

100

Plant species(n)

Adults

Larvae

19

All four species of pest thrips were found more frequently on weeds than native plants (Fig.2.4). Both F. occidentalis (G2 = 23.24 , df = 2 , P = <0.0001), and F. schultzei (G2= 7.11, df = 2 , P = 0.0077), were more likely to be found on weeds and native plants growing <10m from crops than >100m away. This was not the case for either T. tabaci (G2 = 0.73 , df = 2 , P = 0.3929), or T. imaginis (G2 = 0.40 , df = 2 , P = 0.5248), there was no interaction between the type of plant and the distance to crops (Fig. 2.4). Fig. 2.4. Proportions of samples collected from weeds and native plants < 10m and > 100 m from horticulture crops harbouring a) WFT, b) tomato thrips, c) onion thrips, or d) plague thrips

Frank liniella schultzei

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

< 10 m > 100 m

Dis tance to hor ticulture crops

Prop

ortio

n of

flow

er fu

nnel

sa

mpl

es w

ith th

rips

(b )

Frank liniella occidentalis

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Prop

ortio

n of

flow

er fu

nnel

sam

ples

with

th

rips

Native V egetation

Weeds(a)

Thrips im aginis

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

< 10 m > 100 m

Dis tance to hor ticulture crops

(d)

Thrips tabaci

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8Native V egetation

Weeds

(c)

20

Brassica weeds have the highest odds of harbouring F. occidentalis (WFT) 11:1 (ie. of 13 plants, 12 are likely to have F. occidentalis), T. tabaci (4:1) and T. imaginis (3:1). Solanaceous weeds (9.5:1) and the Zygophylaceae (9:1) had the highest odds of harbouring F. schultzei. Wild Mustard, a brassica weed, had the highest average number of WFT per 100 floral units and there were relatively high numbers of Western flower thrips on Rhagodia parabolica when compared to the other native plant species. Atriplex semibaccata, Maireana brevifolia and Eucalyptus tatragona had the lowest number of WFT (Table 2.5). All pest thrips appeared on all weeds but not on all native plant species. There was an overall trend for high numbers of plague thrips on most weeds and some native species for example Eucalyptus tetragona.

Thrips WFT Tomato Onion Plague Indian hedge mustard 49 0 27 99 Wild mustard 138 24 24 277 Wild radish 27 10 9 28 Mallow 53 15 11 41 Thistle 27 6 12 53 Salvation jane 14 6 4 60 Silverleaf nightshade 119 35 4 150 Black nightshade 56 3 6 17 Sour sob 10 6 1 3 Fat hen 7 1 2 20 Atriplex paludosa 8 0 0 0 Atriplex semibaccata 1 0 0 1 Atriplex suberecta 2 0 2 12 Maireana brevifolia 1 0 0 3 Rhagodia crssifolia 3 3 1 1 Rhagodia parabolica 32 0 6 18 Eucalyptus tetragona 0 0 0 213

Table 2.5. The average number of pest thrips1 per 100 floral units2 for weeds and native plants sampled between March 2003 and 2004 on the Northern Adelaide Plains (NAP)

1Thrips data were averaged across all dates at all sampling sites and plant species. 2The average number of floral units per 70ml flower funnel was calculated for each plant species. A floral unit constituted an individual flower measuring greater than or equal to 1 cm diameter or a floret of multiple flowers that were less than 1 cm diameter.

Discussion Pest thrips The dispersal behaviour of the two Frankliniella species and the possibility that they may favour introduced plants with prominent flowers may explain their close proximity to crops that have a persistent weed presence due to irrigation compared to other Thrips spp. These exotic thrips may remain a local problem on weeds as they do not favour long flights making long distance dispersal less likely. The lower frequency but ubiquitous presence of Thrips tabaci also makes them effective potential long distance vectors especially when their small size and flight ability is considered with their tolerance of a broad range of host plants. The high odds of finding pest thrips on weeds indicates that some weeds pose a large threat for crops for example brassica and solanaceous weeds. Growers need to think about weeds immediately adjacent to their crops and also regionally in uncultivated weedy areas to avoid producing ongoing reservoirs of thrips virus vectors. The extremely low odds of finding any of the three introduced pest thrips on native plants indicates that replacing weeds near crops with native plants may reduce the source of thrips that colonise crops. Leafhoppers are not considered vectors of TSWV, but some species are implicated in vectoring other plant diseases. Atriplex spp. hosted large and diverse numbers

21

of leafhoppers that may potentially cause feeding damage, however their potential as pests has not been evaluated. Further research is required to determine whether in the absence of weeds a host shift to native vegetation is likely. Beneficials Even though this horticultural and urban landscape is highly modified, a range of generalist and specialist insects that could benefit horticulture were supported. For example, the brown lacewing Micromus tasmaniae (both the adult and larvae) were caught on a range of plants but were most abundant and breeding on native plants between August and September, a time when lettuce crops are being grown in the area. This is a common insect predator in southern Australia and has been identified as having potential as a bio-control agent as it is a very active larval predator on aphids and frequents low vegetation including crops (Horne et al. 2001). As native saltbushes are increasingly planted in horticultural regions the frequency of leafhoppers on the saltbushes may need to be considered. However, they may not be a serious problem as young native species suites, even when isolated and recently planted can rapidly accumulated suites of specialist parasitoid wasps. Three genera dominated the parasitic wasp assemblages that were found by Stephens et al. (2006) and they contained many important bio-control agents of lepidopteran, hemipteran and thrips pests. It is possible that parasitoids could control leafhoppers, however the reproductive biology of the native hemipteran parasitoids is not well known. Further work to investigate these wasp assemblages as part of an IPM program to control for key pests, as well as leafhoppers, is warranted.

22

3.1. Survey of invertebrates on brassica weeds, native plants and native grasses in the Virginia horticulture area on the Northern Adelaide Plains Introduction The increasing insect pest pressure on the NAP remains a real threat to horticulture in the region. One of the major problems is Tomato Spotted Wilt Virus (TSWV) that is vectored by three introduced pest thrips Frankliniella occidentalis, F. schultzei and Thrips tabaci. Pest and virus damage has cost the industry up to $20 million a year in lost crops and overheads. In addition, Thrips imaginis, a native thrips causes direct feeding damage, but has not yet been recorded as a TSWV vector. Results gained from the pest and beneficial insect surveys of ephemeral weeds and remnant native vegetation on the Northern Adelaide Plains (NAP) at the beginning of this project (Chapter 2) indicate that pest thrips vectors of TSWV harbour and reproduce throughout the year on most of the weeds found on the NAP. However, these pests are rare on native plants and rarer on native grasses. So far these thrips have eluded effective chemical control. Cultural management for pest thrips using a ‘bare earth buffer’ does not maintain topsoil, provide resources for beneficial insects and does not improve biodiversity. There remains a negligible amount of native vegetation growing near horticulture. Replacing the weeds with native plants that are deep-rooted and perennial and do not harbour pest and disease may provide a solution. However, native vegetation planted near crops may inherit the same crop pest problems such as thrips and virus. New pest issues may be created or there may be a host shift for existing pests. This study aimed to determine the seasonal presence and abundance of pest and beneficial insects on three plant categories, weeds, native plants and native grasses indigenous to the NAP to answer two questions; (i) can we grow native plants near crops without harbouring invertebrate pests and (ii) are there differences in the capacity of individual plant species to attract and support various insects? In the first section of this chapter we look at the overall comparison of pest, beneficial and non-target invertebrate guilds on three plant categories; native plants, native grasses and brassica weeds. Differences within invertebrate guilds for the native plant and the native grass categories are dealt with separately in two further sections of this chapter (Chapter 3.2 and 3.3). Materials and methods Study area Sampling of arthropods on weeds, native plants and grasses was conducted at a trial site constructed adjacent to the demonstration greenhouses of Virginia Horticulture Centre Greenhouse Modernisation Project in the Virginia horticulture area. Throughout the sampling period the greenhouses contained tomato crops and the adjacent commercial field (east) was bare earth or cereal crop. The remaining two borders were a main road (south) and a local council amenity area planted with local native plants and trees (west). The surrounding area supports diverse horticultural activities as open or under cover crops (eg. potatoes, carrots, cauliflower, onions, celery, tomatoes, capsicums, lettuce, asian bunch line crops, lemongrass, cucumbers, olives and vineyards).

23

The trial site measured 77.4 x 20.5 m running east west and was 3.3 m south of the greenhouses. The site was split into two sections with the western end 22.7 x 22.5 m for tube stock and direct seeding (divided into six plots) and the eastern end covered in continuous weed mat for tubestock as seed orchard (divided into 10 plots). All plots were of equal size and each plant species was grouped as single species suites. Five plots had one species only and the remaining plots were subdivided, containing up to three species (Table 3.1.1). In addition Acacia victoreae was planted along the eastern fence line of the GMP property between the trial plot and the fence and Eucalyptus tetragona was planted along the western fence line. Six trellises were constructed with pine posts and wire to support 112 Kunzea pomifera (Muntries) plants on the western side of the plot. Table 3.1.1. Design of the 77.4 x 20.5 m trial site adjacent to GMP with position of plant species within trial plots. All plots were divided by one metre wide mulch paths. Native grass plots in the plots with no weed mat were equally divided into mulch and unmulched. The shaded area indicates plots with weed mat

Danthonia linkii

Themeda trianda

Brassica weed

Maireana Enchylaena Atriplex semibaccata A.suberecta (Direct seed)

Rhagodia parabolica

Rhagodia crassifolia

Enchylaena tomentosa

Dianella spp. Melaleuca lanceolata

Olearia ramulosa Goodenia ovata Leptospermum continentale

Aristida behriana

Enneapogon nigricans

Vittidinia spp.

Chloris truncata

Maireana Enchylaena Atriplex semibaccata A.suberecta (Direct seed)

Themeda triandra Enneapogon nigricans

Kunzea pomifera Danthonia linkii

Atriplex semibaccata

Atriplex cinerea Myoporum parvifolium

Atriplex paludosa

North

24

Table 3.1.2. Species list for plants sampled in spring 2005 at the GMP

Family Species Common name Brassicaceae **Rapistrum rugosum L. Giant mustard Chenopodiaceae

**Atriplex semibaccata(R.Br. ) **Atriplex paludosa(R.Br.) **Atriplex cinerea **Rhagodia parabolica(R.Br. ) **Rhagodia crassifolia(R.Br. ) **Enchylaena tomentose(R.Br. ) **Maireana brevifolia (R.Br. )Paul G. Wilson)

Creeping saltbush Marsh saltbush Grey coastal saltbush Mealy saltbush Scented saltbush Ruby saltbush Small leafed bluebush

Mimosaceae **Acacia victoriae (Benth.) Elegant wattle Myrtaceae

**Kunzea pomifera(F. Muell) *Eucalyptus tetragona

Muntries Tallerack

Myoporeaceae *Myoporum parvifolium Creeping boobialla Goodeniaceae *Goodenia ovata Hop goodenia Asteraceae *Olearia ramulose

*Vittidinia spp. Hills daisy New Holland Daisy

Lilliaceae *Dianella spp. Flax lily Poaceae ***Danthonia linkii

***Themeda trianda ***Enneapogon nigricans ***Chloris truncata *Aristida behriana

Wallaby grass Kangaroo grass Black heads Windmill grass Bush wire grass

Note:* Number of Dvac transects per sampling date. *= 1 transect; ** = 3 transects; *** = 6 transects.

Sampling Foliage-associated invertebrates were sampled using a vacuum sampler (21 cc blower/ vac) with cone shaped voile and calico bags (23 cm diameter, 36 cm long tapering to a point) fitted to the end of the suction tube. To standardise sampling, six 2 m transects were marked out in the four native grass plots, with three in the mulch section and three in un-mulched. The vacuum was run over the total foliage area of the plants in each transect for 20 sec. For each of the Chenopodiaceae species the vacuum was run over three random 2 m transects each for 20 sec. Three 2 m transects were also constructed in the weed plot and each transect was vacuumed for 20 seconds. All permanent transect were aligned east-west. The surface of the Kunzea, acacia and eucalypts were vacuumed for 20 sec per species. Perennial native plants (Myrtaceae, Chenopodiaceae and Acacia spp.), native grasses and weed plots were sampled fortnightly during the 2005 spring period (21 September – 14 December 2005). Other newly established native plant species were sampled monthly during spring 2005. Arthropods were removed from the samples and pest and beneficial insects were identified as adult or juvenile and classified to Order and where possible to family and species. All taxa were then allocated to one of three functional guilds; Pests – including all known agricultural pests; Beneficial – including known and potential beneficial invertebrates and Non-target – all remaining invertebrates that were not recorded as pest or beneficial. The four common pest thrips, Western Flower Thrips (WFT) (Frankliniella occidentalis), tomato thrips (Frankliniella schultzei), onion thrips (Thrips tabaci) and plague thrips (Thrips imaginis), a native thrips that causes feeding damage, were identified and included in the pest guild. Analysis Differences in the numbers of the three main invertebrate guilds, pest, beneficial insects and non-target invertebrates, present across the three main vegetation categories: weeds, perennial native plants (Myrtaceae, Chenopodiaceae and Acacia spp.) and native grasses were analysed with a one-way ANOVA of the cumulative number of insects days at the end of the survey period, using the package JMP In version 3.2.6 (SAS Institute Inc. 1996). The cumulative number of insect-days was calculated by the formula:

25

Equation (1) Where n (1 – n) = absolute number of invertebrates caught per 20 second D-Vac on each sampling date t1, t2,….tn = number of days from beginning of experiment (where t1 = 0) Normality of the data was tested within the Shapiro-Wilk test and equality of variances with the O’Brien test. All data was log transformed and for all statistical tests α = 0.05. Means were compared by Tukey’s HSD test when appropriate. Differences in the numbers of the four pest thrips, Western Flower Thrips (WFT) (Frankliniella occidentalis), tomato thrips (Frankliniella schultzei), onion thrips (Thrips tabaci) and native plague thrips (Thrips imaginis) between the three main vegetation types (i.e. brassica weeds, native grasses and native plants) were analysed using a two-way ANOVA of the total number of thrips collected at the end of the spring survey period (three sampling dates: 21 Sept., 5 Oct., and 14-Dec. 2005). Differences in the numbers of the four main thrips between the species within each vegetation type were also analysed with a two-way ANOVA of total insect numbers at the end of the spring survey period. Differences in WFT numbers between the species within each vegetation type were analysed using one-way ANOVAs of total insect numbers, respectively. These tests were repeated for each remaining thrip type, namely tomato, onion and the plague thrips. Analysis was done using the package JMP In version 3.2.6 (SAS Institute Inc. 1996). Normality of the data was tested within the Shapiro-Wilk test and equality of variances with the O’Brien test. All data was log (x + 1) transformed and for all statistical tests α = 0.05. Means were compared by Tukey’s HSD test when appropriate. Results Overall invertebrate pest abundance Analysis at the invertebrate guild level showed there were no significant differences in the numbers of pest invertebrates on the weed versus the native grass and the native plant categories (ANOVA: F2, 57 = 3.035, p = 0.056). Within the native plant category differences in the number of pests were significant between plant species (ANOVA: F9, 30 = 5.15, p = 0.0011) with Tukey Kramer HSD test (α = 0.05) showing that Atriplex semibaccata, Atriplex cinerea, Atriplex paludosa and Maireana brevifolia were all similar to each other and recorded the greatest number of pests. Likewise Rhagodia crassifolia, Acacia victoreae, Kunzea pomifera, Rhagodia parabolica were all similar to each other and had an intermediate number of pest insects when compared with Enchylaena tomentosa and Eucalyptus tetragona, which had the least. Further analysis, also indicated that within the native grass category there were significant differences in the number of pests between grass species (ANOVA: F3, 24 = 6.86, p = 0.0023) with a Tukey Kramer HSD (α = 0.05) showing that Themeda triandra and Enneapogon nigricans were similar and had the highest pest numbers, but were significantly different to both Chloris truncata and Danthonia linkii having lower numbers.

(t3 - t1)

2 2 2(t4 – t2) (t5 - t3) + + ++ n5 (t5 – t4) n1 (t1 - t2) n2 n3 n4

26

Pest thrips There were highly significant differences in total pest thrips: WFT (Frankliniella occidentalis), tomato thrips (Frankliniella schultzei), onion thrips (Thrips tabaci) and plague thrips (Thrips imaginis) numbers across the three main vegetation categories (2-way ANOVA, F2, 228 = 52.13, p < 0.0001) with more pest thrips on the weeds in particular (Fig. 3.1). There were also significant differences between the thrips species with significantly greater plague thrips than the onion thrips, followed by the WFT and tomato thrips (2-way ANOVA: F3, 228 = 98.96, p < 0.0001). There was also a highly significant interaction between vegetation type × thrips species (2-way ANOVA: F6, 228 = 29.03, p < 0.0001) with consistently more of every thrips species on the weeds than the native grasses and native plants, but some native plant species tended to have more onion thrips than the native grasses and some native grass species tended to harbour more plague thrips than the native plants in general. The number of tomato thrips on native grasses and native plants were similar. There were significant differences in total thrips numbers at the species level within the three main vegetation types (ANOVA, F14, 57 = 9.16, p < 0.0001), with the weeds showing more thrips than any particular one species within the native grasses and plant vegetation types. There were significantly more tomato thrips present on the weeds versus both the native grasses and the native plants (ANOVA, F2, 57 = 7.48, p < 0.0001), with Tukey-Kramer HSD test (α = 0.05) indicating that tomato thrips numbers between native grass and native plant species were all similar. There were significant differences in the numbers of onion thrips between the species (ANOVA, F2,

57 = 7.43, p < 0.0001) with Tukey-Kramer HSD test (α = 0.05) indicating that weeds had the highest onion thrips numbers, then Maireana brevifolia was significantly different from the weeds, but both were significantly different from the other native grass and native plant species which all had similarly low numbers of thrips. Fig. 3.1. Comparison of the mean total number of thrips recorded (± SE), Western Flower thrips, tomato thrips, onion thrips and plague thrips across the three main vegetation types sampled on three dates across the spring survey period Finally there were also significant differences in the number of plague thrips between the plant species (ANOVA, F2, 57 = 5.31, p < 0.0001) with the Tukey-Kramer HSD test (α = 0.05) with weeds, Themeda triandra, Enneapogon nigricans, Atriplex cinerea, Acacia victoreae, Kunzea pomifera and Maireana brevifolia having significantly more plague thrips than Chloris truncata, Rhagodia parabolica, Danthonia linkii, Atriplex paludosa, Eucalyptus tetragona, Atriplex semibaccata, R. crassifolia and Enchylaena tomentosa which were all similarly low in terms of plague thrips numbers.

0

50

100

150

200

250

Weeds

Grasses

NativesA

bsol

ute

num

ber o

f pes

t thr

ips

27

Table 3.1.3. Mean number of pest thrips (± S.E.) for brassica weeds native plants and grasses over three dates in spring 2005

Plant species WFT Tomato Onion Plague **Rapistrum rugosum (Brassica weeds) 21.67±5.67 16.00±8.62 50.67±32.19 565.33±200.26 ***Chloris truncata 0.17±0.17 0.00 0.50±0.34 83.83±26.73 ***Danthonia linkii 0.00 0.17±0.17 0.00 55.83±15.18 ***Enneapogon nigricans 0.00 1.00±0.63 0.67±0.49 272.00±143.92 ***Themeda trianda 0.00 0.33±0.21 0.00 889.33±226.20 **Atriplex semibaccata 0.00 0.00 0.00 22.33±9.82 **Atriplex cinerea 0.33±0.33 0.33±0.33 0.67±0.67 144.33±60.07 **Atriplex paludosa 0.00± 0.33±0.33 0.00 45.67±24.31 **Maireana brevifolia 1.33±0.88 0.00 10.00±5.03 67.00±24.83 **Rhagodia parabolica 0.33±0.33 0.33±0.33 0.33±0.33 51.00±15.50 **Rhagodia crassifolia 0.00 0.00 1.33±0.88 21.00±18.04 **Enchylaena tomentose 0.00 0.00 0.00 7.00±2.89 **Acacia victoriae 0.67±0.67 1.00±1.00 2.00±0.58 121.00±33.96 *Eucalyptus tetragona 4.00±3.51 0.33±0.33 5.33±2.73 34.00±27.06 **Kunzea pomifera 2.33±2.33 0.00 4.67±2.33 102.33±62.25

Note: * number of Dvac transects per sampling date. *n=1; ** n=3; *** n=6.

Beneficial Invertebrates There were no significant differences in the numbers of beneficial invertebrates on the weeds versus the native plants and the native grasses (ANOVA: F2, 57 = 2.47, p=0.094). Within the native plant category there were also highly significant differences in the number of beneficial invertebrates between species (ANOVA: F9, 30 = 3.46, P = 0.0099) The Tukey Kramer HSD test (α = 0.05) showed that all native plant species were similar to each other, with the exception of Eucalyptus tetragona, which recorded the far fewer beneficial invertebrates. Predatory Haplothrips species were present on the weeds, all grasses and on native plants that were well represented on the trial plots but not on plants where there were only a few plants per species suite. Further analysis shows that within the native grass category there were significant differences in the number of beneficial invertebrates between grass species (ANOVA: F3, 24 = 3.5, p = 0.35) with the Tukey Kramer HSD test (α = 0.05) indicating that Themeda triandra, Enneapogon nigricans, and Danthonia linkii were all similar and recorded a greater number of beneficial invertebrates than Chloris truncata. Non-Target invertebrates Significant differences in the numbers of non-targets on the weeds versus the native grasses and native plants were found (ANOVA: F2, 57 = 3.61, p = 0.034) with the Tukey Kramer HSD test (α = 0.05) indicating that the number of non-targets on the weeds and native grasses were similar, with significantly fewer non-targets found on the native plants overall. Within the native grass category there were no significant differences in the number of non-targets between grass species (ANOVA: F3, 24 = 0.66, p =0.59). Within the native plants there were highly significant differences in the number of non-target invertebrates between the native plant species (ANOVA: F9, 30 = 8.94, p<0.0001). A Tukey Kramer HSD test (α = 0.05) showed that Rhagodia parabolica was different to all other species and had a

28

significantly greater number of non-targets. All of the other species recorded similar numbers of non-targets. Invertebrate Composition The results above only show the number of invertebrates present on the vegetation sampled, but do not reflect the composition of the invertebrates found. Tables 3.1, 3.2 and 3.3 show the presence and absence scores of all invertebrates sampled on the vegetation during the autumn and spring surveys. The most frequently sampled agriculturally significant pest and beneficial invertebrates seen during the autumn and spring surveys are highlighted in 3.1 and 3.2. Generally, weeds, native plants and native grasses harboured a diverse range of invertebrates across all guilds. Some interesting differences were the absence of tomato thrips on some native plants, the diversity of coccinellid beetles on native grasses and R. parabolica, and the presence of non-target thrips on native grasses. These differences are further investigated in the following two chapter sections (see Chapter 3.1.1 and 3.1.2).

29

Table 3.1.1. Presence/Absence scores of pest insects for vegetation sampled at the GMP site during autumn and spring sampling surveys in 2005 GRASSES SELECTED NATIVE VEGETATION

PEST Invertebrates

Wee

ds

Chl

oris

trun

cata

Enne

apog

on n

igri

cans

Dan

thon

ia li

nkii

Them

eda

tria

ndra

Mai

rean

a br

evifo

lia

Atri

plex

sem

ibac

cata

Rhag

odia

par

abol

ica

Ari

s beh

rian

a

Dia

nella

spp.

Goo

deni

a ov

ata

Ole

aria

ram

ulos

a

Vitti

deni

a sp

p.

Atri

plex

cin

erea

Kun

zea

pom

ifera

Acac

ia v

icto

reae

Atri

plex

pal

udos

a

Rhag

odia

cra

ssifo

lia

Ench

ylae

na to

men

tosa

Euca

lypt

us te

trag

ona

HEMIPTERA * * * * * * * * * * * * * * * * *

^Cicadellidae not specified * * * * * * * * * * * * * * * *

Êmpoascini * * * * * * * * * * * * * *

Ôpsiini * * * * * * * * * * * * * * *

Macrostelini * * * * * *

Iassini * *

Êrythroneurini * * * * * * * * * * * * * * * * * *

Fulgoroidea (Flatidae) * * * * *

Delphacidae * * * * * * * * * * * *

Berytidae * * *

^Lygaedae * * * * * * * * * * * * * * * * *

^Nysius vinitor (Rutherglen bug) * * * * * * * * * * * * * * * * * * * *

Psyllidae * * * * * * * * *

Pentatomidae * * * * *

^Miridae * * * * * * * * * * * * * * * * * *

Âleyrodidae (white fly) * * * * * * * * * * * * * * * * * * * *

Âphididae (no wings) * * * * * * * * * * * * * * * * * * *

Âphididae (wings) * * * * * * * * * * * * *

Membracidae * * *

LEPIDOPTERA (Plutella sp.) *

*

^THYSANOPTERA (damaged ) * * * * * * * * * *

^Western Flower Thrips * * * * * * * * * * * * * * *

^Tomato thrips * * * * * * * * *

Ônion thrips * * * * * * * * * * * * * * * *

^Plague thrips * * * * * * * * * * * * * * * * * * * *

ACARINA (Red legged earth mite) * * * * * * * *

Note: ^ indicates most frequent invertebrates sampled across spring survey period in the pest category

30

Table 3.1.2. Presence/Absence scores of beneficial insects for vegetation sampled at the GMP site during autumn and spring sampling surveys in 2005

GRASSES SELECTED NATIVE VEGETATION

BENEFICIAL Invertebrates

Wee

ds

Chl

oris

trun

cata

Enne

apog

on n

igri

cans

Dan

thon

ia li

nkii

Them

eda

tria

ndra

Mai

rean

a br

evifo

lia

Atri

plex

sem

ibac

cata

Rhag

odia

par

abol

ica

Ari

s beh

rian

a

Dia

nella

spp.

Goo

deni

a ov

ata

Ole

aria

ram

ulos

a

Vitti

deni

a sp

p.

Atri

plex

cin

erea

Kun

zea

pom

ifera

Acac

ia v

icto

reae

Atri

plex

pal

udos

a

Rhag

odia

cra

ssifo

lia

Ench

ylae

na to

men

tosa

Euca

lypt

us te

trag

ona

HEMIPTERA

Nabidae * * * * * * * * * * * * * * *

Anthocoridae * * * * * * *

Geocoridae *

COLEOPTERA * * * * * * *

Coccinellidae * * * * * * * * * *

Coccinella transversalis * * * * * * *

Harmonia conformis *

Hippodamia variegata * * * * * * *

Diomus notescens * * * * * * * * * * * *

Anthicidae * * * * * * * * * * *

Lathridiidae * * * * * * * * * * * * * * * * * * * *

NEUROPTERA * *

^Micromus tasmaniae (Brown lacewing)

* * * * * * * * * * * * * * * *

*

*

Chrysopidae (Green lacewing) * * * * * * * * * * * * * *

^ACARINA (predatory native mites * * * * * * * * * * * * * * * * * *

^ARANEAE (all spiders) * * * * * * * * * * * * * * * * * * * *

^HYMENOPTERA (parasitoid wasps)

* * * * * * * * * * * * * * * * * * * *

DIPTERA (Syrphidae) * * * * * * *

*

MANTODEA (Mantidae) * *

THYSANOPTERA * * * * * * * * * * *

^Haplothrips robustus * * * *

^Haplothrips victoriensis * * * * *

*

^Haplothrips sp. * * * * * * * * * * * *

Note: ^ indicates most frequent invertebrates sampled across spring survey period in the beneficials category

31

Table 3.1.3. Presence/Absence scores of non-target invertebrates for vegetation sampled at the GMP site during autumn and spring sampling surveys in 2005

GRASSES SELECTED NATIVE VEGETATION

NON-TARGET Invertebrates

Wee

ds

Chl

oris

trun

cata

Enne

apog

on n

igri

cans

Dan

thon

ia li

nkii

Them

eda

tria

ndra

Mai

rean

a br

evifo

lia

Atri

plex

sem

ibac

cata

Rhag

odia

par

abol

ica

Ari

s beh

rian

a

Dia

nella

spp.

Goo

deni

a ov

ata

Ole

aria

ram

ulos

a

Vitti

deni

a sp

p.

Atri

plex

cin

erea

Kun

zea

pom

ifera

Acac

ia v

icto

reae

Atri

plex

pal

udos

a

Rhag

odia

cra

ssifo

lia

Ench

ylae

na to

men

tosa

Euca

lypt

us te

trag

ona

HEMIPTERA * *

Scale insects * * * * * * * * * * *

Psylloidea * * * * *

COLEOPTERA * * * * * * * * * * * * * * * *

Corylophidae * * * * * * * *

DERMAPTERA * * * * * * *

PSOCOPTERA wingless * * * * * * * * * * * * * * * * * * *

winged * *

LEPIDOPTERA * * * * * * * * * * * * * * * * * *

ORTHOPTERA * *

HYMENOPTERA (bees) * * * * * * * * * * *

Formicidae * * * * * * * * * * * * * * * * *

DIPTERA * * * * * * * * * * * * * * * * * * * *

THYSANOPTERA (not specified) * * * * * * * * * * * * * * * * * * *

Chirothrips manicatus * * * * * * * * * * * * *

Desmothrips sp. * * * * * * *

Anaphothrips sp. * * * * * * * * * * * * *

Thrips australis * * * * * * * *

BLATTODEA * *

THYSANURA * * * *

ACARINA (mites) * * * * * * * * * * * * * * * * *

COLLEMBOLA * * * * * * * * * * * * * * * * * * *

MOLLUSCA (snails) * * * * * * * * * * * *

ISOPODA (Slaters) * * * *

ARACHNIDA (Pseudoscorpion) * * * *

CHILOPODA (Centipedes) * * *

DIPLOPODA (Millipedes) * * * * * * * * * * *

32

Discussion In this study, the overall abundance of invertebrates was similar regardless of whether the plants sampled were native perennials, native grasses or weeds. This result, perhaps, reflects the general capacity of plants to support invertebrates in this environment. However, when comparisons are made using functional guilds, i.e. pest or beneficial, then interesting differences in invertebrate groupings become apparent. The abundance of known pest species varied significantly on different native plants. For instance, Atriplex spp. and Maireana brevifolia recorded the highest pest numbers on native plants. High pest numbers are indicative, but it is important to determine which pest species predominate on plants to assess the risk to nearby horticultural crops. On the NAP, introduced pest thrips are very important because they are associated with vectoring TSWV. Weeds consistently maintained higher levels of pest thrips species compared to both native plants and grasses. Plague thrips were the most abundant pest thrips, and a selected few native plant and grass species harboured relatively high numbers. Interestingly, the native plague thrips were highly selective, with significant differences in abundance between species within the same genus (Atriplex). This suggests that plant selection to reduce particular pests may be very specific. The importance of plague thrips on the NAP is low compared to other pest thrips species that vector TSWV, such as WFT. The present study shows that the abundance of WFT on weeds was an order of magnitude higher than most native plants and grasses. This represents a significant reduction in the presence of this important pest. However, it is still unclear whether some of these native plants and grasses will host other pests that may in time emerge as new problems. The determination of the predominant species on different plants may provide insights into potential pest risks, and is examined in later sections. Weeds harbour beneficial insects and mites, but the presence of key pest thrips negates any benefits. The present study indicates that native plants and grasses harbour similar numbers of beneficial insects to weeds. As the native plants and grasses also harbour fewer WFT, this may provide a relative benefit. However, species composition (eg. generalist brown lacewing or specific parasitic wasps) may be more important than overall beneficial abundance. The species composition for different plants is examined in more detail in later sections. In addition, there is a substantial group of invertebrates classed as non-target. The non-target group represents species of unknown importance, rather than non-pest or non-beneficial. It may be that many of the species will not impact on nearby horticultural crops. However, some beneficial or pest species may emerge with larger plantings of these plant and grass species. An example is the diversity of coccinellid species on the native grasses and Rhagodia parabolica, most of which were absent from the weeds. Some of these species may emerge as contributors to IPM. In addition, some of the non-target species may provide indirect benefits as a food source for generalist predators during breaks in the cropping cycle. The native grasses harboured native thrips, which are unlikely to be pest of horticultural crops, but may provide alternative hosts for parasitic wasps associated with the control of pest thrips. Overall, the results suggest that a reduction in the key thrips species may be possible, but the replacement of weeds by native plants should not be left to chance. This confirms the concept of informed and deliberate plant selection, which we collectively refer to as ‘revegetation by design’.

33

3.2. Invertebrate abundance and composition on selected native perennial plants and brassica weed plots on the Northern Adelaide Plains Introduction Native perennial plants are presented as potential replacements for common weedy species that are known to harbour Western Flower thrips (WFT). However, very little is known about the invertebrate abundance and composition on many of these native species. The Northern Adelaide Plains (NAP) is almost devoid of native vegetation, and it is unclear what impact the introduction of various native plants would have on the pest population dynamics of nearby horticulture. The intention was to establish native plant species that could suppress pest populations, particularly WFT, by providing a less suitable plant host (‘bottom-up’ effects) and enhance natural enemy populations (‘top-up’ effects) (Gurr et al 2003). On the NAP, a comparison of native plants with common brassica weeds is important to assess any potential improvement or deterioration from the current situation. In addition, native plants should be evaluated for the emergence of ‘new pests’. In response, native plant species and brassica weed plots were established near horticulture on the NAP, and were sampled throughout spring 2005. We examined the invertebrate fauna on the different plant species, and categorised invertebrates according to their function, i.e. beneficial or pest. The function of many invertebrates in agro-systems is not yet known, and were categorised as ‘non-target’. The objectives of this study was to; (i) determine the potential of native plant species to harbour the four major pest thrips species, WFT, onion thrips, tomato thrips and plague thrips and, (ii) determine the potential of native plant species to harbour other pest and beneficial invertebrates. In both instances, the native plant species were compared with the brassica weeds. Materials and Methods Sampling methods are outlined in Chapter 3.1 for native perennial plants; Maireana brevifolia, Atriplex semibaccata and Rhagodia parabolica, and brassica weed plots sampled fortnightly between 9 September and 14 December 2005. Briefly, 25 m2 plots of individual native plants and brassica weeds were established at the Greenhouse Modernisation Project (GMP), Virginia. Three 2 m transects within each plot were sampled by D-Vac for 20 seconds, and the invertebrates collected were categorised by functional guild. The trial plots of native plants and weeds was involved in the flooding event on 8 November 2005 when the Gawler River burst its banks and flowed onto the Adelaide Plain. The plots were submerged in floodwater for three days, and this event delayed the next scheduled sampling. Mean numbers of invertebrate taxa were calculated for each invertebrate guild, ie, pest, beneficial and non-target, for each native perennial species, Maireana brevifolia, Atriplex semibaccata, Rhagodia parabolica and the brassica weeds. In addition, mean number of each pest thrips was calculated for each native plant species and weed. Cumulative insect days at the end of the spring sampling period were calculated using Equation (1) in Chapter 3.1. Cumulative insect days and mean thrips numbers were analysed using ANOVA. Analysis was performed using the package JMP In version 3.2.6 (SAS Institute Inc. 1996). Normality of the data was tested with the Shapiro-Wilk test and equality of variances with the O’Brien test. In all

34

cases, departure from the hypothesis meant that the invertebrate data was log transformed, and the thrips data was log (x+1) transformed. Means were compared by Tukey’s HSD test when appropriate. Results A comparison of invertebrate guilds on native plants species and brassica weeds The total invertebrate numbers were similar for native plants and brassica weed, except for Atriplex semibaccata, which recorded the highest overall densities (2-way ANOVA, F3, 36 = 13.43, p < 0.0001). The plant species were significantly different in the proportions of invertebrates in each guild, with more pest and non-target invertebrates than beneficial invertebrates on the native plants and the weeds (2-way ANOVA, F2, 36 = 252.23, p < 0.0001). In addition, some species harboured higher densities of invertebrates in different guilds (2-way ANOVA, F6, 36 =36.52, p < 0.0001); for example, Rhagodia parabolica recorded the highest number of non-targets, whereas brassica weeds and Atriplex semibaccata had the highest number of pests. The relative proportions of invertebrates in functional guilds over the spring period can be seen for brassica weeds and each native perennial plant in figures 3.2.1 to 3.2.4. The difference in the guild proportions is reflected in differences in the composition of the invertebrates on each plant species and, in particular, the most prevalent taxa within each guild. The most prevalent taxa within each functional guild (eg. pest, beneficial or non-target) for each plant species is presented in Tables 3.2.1 to 3.2.4, and allows comparisons of the potential pest risk or benefit associated those plant species. The pest thrips species, with the notable exception of plague thrips, were not abundant on the native plants, but brassica weeds also harboured significant densities of WFT. Due to their importance as virus vectors they are reviewed in more detail in the next section. In regard to non-thrips pests, Rutherglen bug and various pest aphids were most prevalent on brassica weeds. Whereas, native plants tended to have more leafhoppers and mirids. Leafhoppers were very abundant on A. semibaccata, with most within the tribe Empoascini. In regard to beneficial taxa, the native plants support higher overall densities than the brassica weeds. Parasitic wasps were the most prevalent beneficial taxon on both weeds and native plants, but the native plants recorded higher (x2) spring densities. Native plants also recorded much higher densities of spiders, and more predatory mites on A. semibaccata. The most prevalent non-target taxon was whitefly Rhagodia parabolica. Although highly abundant on R. parabolica, they were not evident on nearby plots or weeds. On other native plant species, adult flies and Collembola were most prevalent. The native plants and brassica weeds also recorded significant mites and thrips, but their function was not clear.

35

Rapistrum rugosum (Brassica weed)

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

20-Aug-05

17-Sep-05

15-Oct-05

12-Nov-05

10-Dec-05

7-Jan-06

Date

Cum

ulat

ive

inse

ct d

ays

Pests Beneficials Non-Targets

Fig. 3.2.1. Cumulative numbers of insect-days for the three main invertebrate categories: pests, beneficials and non-targets present on brassica weeds at the GMP site across the spring 2005 sampling period. Data represent mean ± S.E. (n = 3) Table 3.2.1. Spring mean densities of prevalent taxa and the proportion within each functional guild on brassica weeds

Guild Taxon Spring mean densities* Proportion/guild Plague thrips 1,550 59.2% Rutherglen bug 420 16.1% Aphids (non-specified) 157 6.0%

Pest

Western flower thrips 111 4.3% Wasps (parasitic) 117 63.1% Mites (predatory)^ 14.3 7.7% Haplothrips (predatory) 7.7 4.1% Brown lacewings 6.3 3.4%

Beneficial

Spiders (various) 5.0 2.7% Thrips (non-specified)## 146 39.9% Flies 114 31.2% Collembola 8.3 2.3% Seed-eating thrips### 4.7 1.3%

Non-target

Mites (non-specified) ^^ 2.7 0.7%

Note: *Mean of three 20s D-Vac samples per plot. Spring values are the sum of invertebrates recorded from seven sampling periods between Sept 9. and Dec. 14 2005. ^ Predatory mites from the families; Erythraeidae, Bdellidae, Teneriffidae and Camerobidae. ^^ Mainly Beetle mites (Oribatidae) ## Includes a range of adult thrips (eg, Anaphothrips) and indistinguishable juvenile specimens. ### Chirothrips manicatus

36

Atriplex semibaccata

0

20000

40000

60000

80000

03-Sep-05

17-Sep-05

01-Oct-05

15-Oct-05

29-Oct-05

12-Nov-05

26-Nov-05

10-Dec-05

date

cum

ulat

ive

inse

ct d

ays

Non-Targets Beneficials Pests

Fig. 3.2.2. Cumulative number of insect-days for the three main invertebrate categories: pest insects, beneficial invertebrates and non-targets present on Atriplex semibaccata at the GMP for the spring 2005 sampling periods. Data represent mean ± S.E. (n = 3) Table 3.2.2. Spring mean densities of prevalent taxa and the proportion within each functional guild on Atriplex semibaccata

Guild Taxon Spring mean densities* Proportion/guild Leafhoppers 2,887 87.8% Mirids 276 8.4% Plague thrips 674 2.1%

Pest

Wasps (parasitic) 294 63.7% Mites (predatory)^ 95.3 20.1% Spiders (various) 32.0 6.9% Brown lacewings 6.3 1.4%

Beneficial

Haplothrips (predatory) 6.3 1.4% Collembola 3,967 90.3% Flies 144 3.3% Mites (non-specified) ^^ 67.7 1.5% Pscoptera (book lice) 11.7 0.3%

Non-target

Thrips (non-specified) ## 8.7 0.2%

Note: *Mean of three 20s D-Vac samples per plot. Spring values are the sum of invertebrates recorded from seven sampling periods between Sept. 9 and Dec. 14 2005. ^ Predatory mites from the families; Erythraeidae, Bdellidae, Teneriffidae and Camerobidae. ^^ Mainly Beetle mites (Oribatidae) ## Includes a range of adult thrips (eg, Anaphothrips) and indistinguishable juvenile specimens.

37

Maireana brevifolia

0

2000

4000

6000

8000

10000

12000

14000

16000

16-Aug-0505-Sep-05

25-Sep-0515-Oct-05

04-Nov-0524-Nov-05

14-Dec-05

date

cum

ulat

ive

inse

ct d

ays


Fig. 3.2.3. Cumulative number of insect-days for the three main invertebrate categories: pest insects, beneficial invertebrates and non-targets present on Maireana brevifolia at the GMP for the spring 2005 sampling periods. Data represent mean ± S.E. (n = 3) Table 3.2.3. Spring mean densities of prevalent taxa and the proportion within each functional guild on Maireana brevifolia

Guild Taxon Spring mean densities* Proportion/guild Leafhoppers 384 39.4% Plague thrips 378 38.9% Mirids 143 14.7%

Pest

Wasps (parasitic) 199 55.2% Spiders (various) 137 38.1% Haplothrips (predatory) 12.3 3.4% Mites (predatory) ^ 3.0 0.8%

Beneficial

Brown lacewings 1.3 0.4% Flies 230 62.9% Collembola 98.7 26.9% Thrips (non-specified) ## 14.7 4.0% Pscoptera (book lice) 14.7 4.0%

Non-target


Note: *Mean of three 20s D-Vac samples per plot. Spring values are the sum of invertebrates recorded from seven sampling periods between Sept. 9 and Dec. 14 2005. ^ Predatory mites from the families; Erythraeidae, Bdellidae, Teneriffidae and Camerobidae. ^^ Mainly Beetle mites (Oribatidae) ## Includes a range of adult thrips (eg, Anaphothrips) and indistinguishable juvenile specimens.

38

Rhagodia parabolica

0

20000

40000

60000

80000

100000

120000

140000

160000

20-Aug-05

17-Sep-05

15-Oct-05

12-Nov-05

10-Dec-05

07-Jan-06

date

cum

ulat

ive

inse

ct d

ays


Fig. 3.2.4. Cumulative number of insect-days for the three main invertebrate categories: pest insects, beneficial invertebrates and non-targets present on Rhagodia parabolica at the GMP for the spring 2005 sampling periods. Data represent mean ± S.E. (n = 3) Table 3.2.4. Spring mean densities of prevalent taxa and the proportion within each functional guild on Rhagodia parabolica

Guild Taxon Spring mean densities* Proportion/guild Mirids 278 56.6% Plague thrips 97.3 19.9% Leafhoppers 75.7 15.4%

Pest

Wasps (parasitic) 211 61.3% Spiders (various) 96.3 27.9% Haplothrips (predatory) 3.0 0.9% Brown lacewings 2.7 0.8%

Beneficial

Mites (predatory) ^ 1.0 0.3% Whitefly (non-specified)# 36,848 94.3% Flies 330 3.9% Pscoptera (book lice) 119 1.4% Thrips (non-specified) ## 62.0 0.7%

Non-target

Collembola 60.3 0.7%

Note: *Mean of three 20s D-Vac samples per plot. Spring values are the sum of invertebrates recorded from seven sampling periods between Sept. 9 and Dec. 14 2005. ^ Predatory mites from the families; Erythraeidae, Bdellidae, Teneriffidae and Camerobidae. # Adults not identified, but examination of puparium suggest many of native origins (Gabrellia Caon, pers. comm.). ## Includes a range of adult thrips (eg, Anaphothrips) and indistinguishable juvenile specimens.

39

A comparison of key pest thrips on native perennial plant species and weeds The most serious pests thrips are the species that vector TSWV, and, in particular, WFT. Rapistrum rugosum , a common brassica weed, recorded by far the highest WFT densities (ANOVA, F3, 12 = 92.07, p < 0.0001) when compared to the three native perennial plants (Table 3.2.5). This trend of higher densities also occurred with the other two thrips species that vector TSWV, tomato thrips (ANOVA, F3, 12 = 31.6, p < 0.0001) and onion thrips (ANOVA, F3, 12 = 14.88, p = 0012). All three thrips species had low numbers on native plants, except Maireana brevifolia , which recorded higher onion thrips and WFT than the other two native plants. Interestingly, no tomato thrips were recorded on Maireana brevifolia and Atriplex semibaccata during the entire spring sampling period. Although plague thrips do not vector TSWV, they are abundant pests during spring. Brassica weeds recorded significantly higher plague thrips numbers than the native species (ANOVA, F3, 12 = 55.84, p < 0.0001). Maireana brevifolia recorded higher plague thrips numbers than both Rhagodia parabolica and Atriplex semibaccata. All plants recorded large densities of plague thrips when compared to the three TSWV vectoring thrips species. Table 3.2.5. Spring mean densities (± SE) per 20s D-Vac of four pest thrips species found on native perennial species and brassica weeds (n=3)

Species

Western Flower Thrips

Tomato thrips

Onion thrips

Plague thrips

Atriplex semibaccata 0.33 ± 0.33c* 0b 3 ± 1.53c 67.67 ± 16.68c Maireana brevifolia 6.33 ± 0.88b 0b 15 ± 4.36b 379.33 ± 60.4b Rhagodia parabolica 2.33 ± 0.88c 0.33 ± 0.33b 1.67 ± 0.67c 130.67 ± 4.81c Rapistrum rugosum 111.33 ± 17.53a 19.67 ± 0.928a 68.67 ± 32.03a 1550.00 ± 341.01a

Note: * Means in each column followed by a different letter are significantly different (p>0.05, Tukey-Kramer HSD test). Spring values are the sum of thrips recorded from seven sampling periods between Sept. 9 and Dec. 14 2005.

Discussion This study was conducted to determine whether indigenous perennial native species, such as Maireana brevifolia, Atriplex semibaccata, Rhagodia parabolica, are less suitable hosts of invertebrate pests, particularly of WFT, than common brassica weeds, such as Rapistrum rugosum, when grown near horticulture on the NAP. The results indicate that the brassica weeds and A. semibaccata had the highest pest densities over spring. However, the types of pest on the different plant species varied. This is important because certain pests, such as WFT, tomato thrips and onion thrips, have greater importance due to their ability to vector TSWV. In this study, the abundance of WFT on Brassica weeds during spring was 300 times higher than on A. semibaccata. The other primary native plant species, Maireana brevifolia and Rhagodia parabolica, also recorded very low densities of WFT compared to the brassica weeds. The three native plant species recorded much lower tomato and onion thrips than the brassica weeds. Generally, pest thrips numbers were very low or absent, with the exception of M. brevifolia, which recorded higher onion thrips when compared to the other two primary native plants. Plague thrips were by far the most abundant pest thrips species on all primary native plant species and brassica weeds. The brassica weeds recorded the highest numbers, but the native plants also supported relatively high number of plague thrips. Although they were the dominant thrips species, their importance as pests is reduced because they do not vector TSWV. In regard to other potential pests, A. semibaccata are harbouring high numbers of leafhoppers. Currently on the NAP, leafhoppers are considered to pose an occasional threat where growers do not manage their spray program within crops. In recent years leafhopper vectored disease such as Purple Top and Tomato Big Bud have rarely been reported and have occurred as isolated cases (D. Cavallaro per comm.). In this study, few leafhoppers were found on Rapistrum rugosum, but other weeds may be supporting more leafhoppers. A. semibaccata harboured many leafhoppers, but most were within the tribe Empoasiini, rather than Orosius argentatus, which is recognised as an important vector of these diseases. Regardless, A. semibaccata may harbour other leafhoppers that vector phytoplasmids, and

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the taxonomy of leafhoppers on native plants requires further evaluation to determine whether they present a significant threat. Any assessment of pest risk must take into account the phenology and longevity of the plants. During plant establishment, A. semibaccata’s vigorous spreading habit has allowed it to colonise early and out compete many weeds, but when grown in a mixed sward with other native species it is rapidly succeeded. Fortunately, native plants vary in their capacity to support different invertebrates, and M. brevifolia and R. parabolica harboured much lower densities of leafhoppers than A. semibaccata. Plant succession through careful plant choice may reduce the potential risk of leafhoppers within a few seasons from plant establishment. The reduction of pests by establishment of less suitable plant host is the primary concern, but these plants may also enhance natural enemies and support IPM strategies. A range of beneficial invertebrates was found on both the brassica weeds and native plants, including parasitic wasps, predatory mites, spiders, predatory thrips and brown lacewings. The native plant species harboured a more abundant and diverse fauna, with relatively numerous egg parasitoids (Stephens et al. 2006). It is not possible to estimate the contribution of any of these invertebrates to the control of key pests on the NAP. However, the greater abundance and diversity on native plants, including specialist and generalist predators, provide greater potential for benefit. Further investigations on the beneficial suite of invertebrates on native plants, particularly parasitic wasps associated with control of thrips, are warranted. In addition, there is a substantial group of invertebrates classed as non-target. The non-target group represents species of unknown importance, rather than non-pest or non-beneficial. In this study, Rhagodia parabolica supported large densities of whitefly, which was not identified as an endemic pest species or evident on nearby plants. At this stage, the whitefly are categorised as non-target, but they require further evaluation. The majority of non-target invertebrates on other native plants were adult flies and Collembolan, which are unlikely to impact on nearby horticultural crops. However, some beneficial or pest species may emerge with larger plantings of these native plants. Further studies are required to determine whether some of these invertebrates may contribute to new pest problems or, alternatively, enhance natural enemies. Interesting areas for further work are the whitefly on Rhagodia parabolica, and indirect benefits of non-target invertebrates as hosts for generalist predators during breaks in the cropping cycle. Overall, the native perennials have shown significant variation in the composition and abundance of various invertebrates despite their close proximity to each other. This trend is likely to occur with other native plant species, and may vary with seasonal conditions or sampling frequency. For instance, recent survey results from the GMP suggest that Atriplex paludosa attracts large aggregations of brown lacewings, but only for a short period over spring (G. Wood, unpublished data). In conclusion, the native plants used in this trial are unsuitable hosts for the most serious pest on the NAP, Western Flower thrips. However, a greater understanding of the invertebrates on a larger range of native plant species is required make an informed choices on suites of plants that will pose no new pest threats and enhance natural enemies.

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3.3. Invertebrate abundance and composition on selected native grasses and brassica weed plots on the Northern Adelaide Plains Introduction Native grasses may be suitable to replace weeds on the Northern Adelaide Plains (NAP) provided they can establish, compete with common weeds, and do not harbour pests. Judgements can be made on the first two criteria, but little is known about the types of invertebrates that may flourish on native grasses. Chloris truncata, Themeda triandra and Enneapogon nigrans are a summer growing species that commonly occur in the Virginia district. They have some tolerance to glyphosate and are often found growing on road shoulders where they take advantage of summer rain that runs off the sealed carriageway. Being of relatively low height, both species were considered ideal for planting on horticultural premises where they would provide groundcover with minimal fire risk and not shade crops in the greenhouse. Other grass species, such as Danthonia linkii should also respond well to the conditions of the NAP. In this section, the aim is to; (i) determine the potential of native plant species to harbour the four major pest thrips species, WFT, onion thrips, tomato thrips and plague thrips, and (ii) determine the potential of native plant species to harbour other pest and beneficial invertebrates. In both instances, the native plant species were compared with brassica weeds. Materials and Methods Sampling methods are outlined in Chapter 3.1. Four native grass species Chloris truncata, Enneapogon nigricans, Danthonia linkii and Themeda triandra were sampled in autumn between February and May on five dates and the same grass transects were sampled fortnightly in spring between September and December on seven dates. Brassica weed, Rapistrum rugosum, plots established near native plant and grass plots were also sampled in spring. Analysis was performed on spring data only. Mean numbers of invertebrate taxa were calculated for each invertebrate guild, ie, pest, beneficial and non-target, for each native grass species and the brassica weeds. In addition, mean number of each pest thrips was calculated for each native plant species and weed. Cumulative insect days at the end of the spring sampling period were calculated using Equation (1) in Chapter 3.1. Cumulative insect days and mean thrips numbers were analysed using ANOVA. Analysis was done using the package JMP In version 3.2.6 (SAS Institute Inc. 1996). Normality of the data was tested within the Shapiro-Wilk test and equality of variances with the O’Brien test. In all cases, departure from the hypothesis meant that the invertebrate data was log transformed, and for all statistical tests α = 0.05. Means were compared by Tukey’s HSD test when appropriate.

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Results A comparison of invertebrate guilds on four native grass species and brassica weeds for the spring period. Overall, the abundance of invertebrates was higher during spring for most grasses (Figs. 3.3.1-3.3.5). During spring, brassica weed plots were established to allow comparisons between the invertebrate fauna on each grass species and weeds. As such, comparisons are made between the native grasses and the brassica weed, Rapistrum rugosum, only during the spring period. Comparisons between native grasses during autumn will be subject to separate analysis in subsequent reports. The invertebrate numbers were similar for native grasses and weeds, except for Themeda triandra, which recorded higher overall densities (2-way ANOVA, F4, 81 = 9.16, p < 0.0001) There were significantly more pest and non-target invertebrates than beneficial invertebrates on the native grasses and the weeds (2-way ANOVA, F2, 81 = 44.26, p < 0.0001) and a highly significant interaction between species and invertebrate guilds (2-way ANOVA, F8, 81 = 5.61, p < 0.0001), which reflects that individual plant species vary in their capacity to support the three invertebrate guilds. For example, Enneapogon recorded the highest numbers of non-target invertebrates, whereas the brassica weeds and Themeda recorded the highest number of pests. The individual plant species also supported different invertebrate taxa. The most prevalent taxa within each functional guild is presented in tables 3.3.1 to 3.3.5, and allows comparisons of the potential pest risk or benefit associated with those plant species. The pest thrips species, with the notable exception of native plague thrips, were not abundant on the native plants, but brassica weeds harboured significant numbers of WFT. Due to their importance as virus vectors they are reviewed in more detail in the next section. In regard to non-thrips pests, Rutherglen bug and various pest aphids were most prevalent on brassica weeds. Three native grasses, Chloris truncata, Enneapogon nigricans and Danthonia linkii also supported Rutherglen bug and aphids, but predominately, the cotton aphid, Aphis gossypii. In regard to beneficial invertebrates, all native grasses harboured parasitic wasps, and Chloris truncata, Themeda triandra and Danthonia linkii supported significant densities of predatory mites from the families; Erythraeidae, Bdellidae, Teneriffidae and Camerobidae. The most prevalent non target taxa were Collembola and adult flies, except Chloris truncata and Enneapogon nigricans, which also supported large numbers of an introduced seed-eating thrips, Chirothrips manicatus. These thrips were associated with the seed-heads of these grasses.

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Rapistrum rugosum (Brassica weed)

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Figure 3.3.1. Cumulative numbers of insect-days for the three main invertebrate categories: pests, beneficials and non-targets present on brassica weeds at the GMP site across the spring 2005 sampling period. Data represent mean ± S.E. (n = 3) Table 3.3.1. Spring mean densities of prevalent taxa and the proportion within each functional guild on brassica weeds

Guild Taxon Spring mean densities* Proportion/guild Plague thrips 1,550 59.2% Rutherglen bug 420 16.1% Aphids (non-specified) 157 6.0%

Pest

Western flower thrips 111 4.3% Wasps (parasitic) 117 63.1% Mites (predatory) ^ 14.3 7.7% Haplothrips (predatory) 7.7 4.1% Brown lacewings 6.3 3.4%

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Spiders (various) 5.0 2.7% Thrips (non-specified) ## 146 39.9% Flies 114 31.2% Collembola 8.3 2.3% Seed-eating thrips### 4.7 1.3%

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Note: *Mean of three 20s D-Vac samples per plot. Spring values are the sum of invertebrates recorded from seven sampling periods between Sept. 9 and Dec. 14 2005. ^ Predatory mites from the families; Erythraeidae, Bdellidae, Teneriffidae and Camerobidae. ^^Mainly Beetle mites (Oribatidae) ##Includes a range of adult thrips (eg, Anaphothrips) and indistinguishable juvenile specimens. ###Chirothrips manicatus

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Chloris truncata (Windmill grass)

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Figure 3.3.2. Cumulative number of insect-days for the three main invertebrate guilds: pests, beneficial and non-target invertebrates present on Chloris truncata at the GMP site across the autumn and spring 2005 sampling periods. Data represent mean ± S.E. (n = 6) Table 3.3.2. Spring mean densities of prevalent taxa and the proportion within each functional guild on Chloris truncata

Guild Taxon Spring mean densities* Proportion/guild Aphids (non-specified)# 277 41.0% Plague thrips 90.3 13.3% Chinch bugs (non-specified)

36.6 5.4%

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Wasps (parasitic) 51.3 34.0% Mites (predatory) ^ 36.3 24.1% Spiders (various) 26.3 17.5% Haplothrips (predatory) 11.0 7.3%

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Brown lacewings 2.7 1.8% Collembola 771 65.4% Flies 105 8.9% Seed-eating thrips### 42.3 3.6% Pscoptera (book lice) 17.0 1.4%

Non-target

Mites (non-specified)^^ 4.7 0.4%

Note: *Mean of three 20s D-Vac samples per plot. Spring values are the sum of invertebrates recorded from seven sampling periods between Sept. 9 and Dec. 14 2005. ^ Predatory mites from the families; Erythraeidae, Bdellidae, Teneriffidae and Camerobidae.

^^Mainly Beetle mites (Oribatidae) ### Chirothrips manicatus

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Enneapogon nigricans (Black-head grass)

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Figure 3.3.3. Cumulative number of insect-days for the three main invertebrate categories: pest insects, beneficial invertebrates and non-targets present on Enneapogon nigricans at the GMP site across the autumn and spring 2005 sampling periods. Data represent mean ± S.E. (n = 6) Table 3.3.3. Spring mean densities of prevalent taxa and the proportion within each functional guild on Enneapogon nigricans

Guild Taxon Spring mean densities* Proportion/guild Aphids (non-specified)# 484 53.2% Plague thrips 136 14.9% Chinch bugs (non-specified)

35 3.9%

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Wasps (parasitic) 78.7 44.7% Spiders (various) 30.7 17.4% Haplothrips (predatory) 17.0 9.7% Mites (predatory)^ 12.7 7.2%

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Brown lacewings 7.7 4.4% Collembola 848 69.8% Seed-eating thrips### 112 9.2% Flies 64.7 5.3% Mites (non-specified)^^ 20 1.7%

Non-target

Pscoptera (book lice) 12 1.0% Note: *Mean of three 20s D-Vac samples per plot. Spring values are the sum of invertebrates recorded from seven sampling periods between Sept. 9 and Dec. 14 2005. # Predominately cotton aphid, Aphis gossypii. ^Predatory mites from the families; Erythraeidae, Bdellidae, Teneriffidae and Camerobidae. ^^Mainly Beetle mites (Oribatidae) ###Chirothrips manicatus

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Danthonia linkii (Wallaby grass)

Figure 3.3.4. Cumulative number of insect-days for the three main insect categories: pest insects, beneficial invertebrates and non-targets present on Danthonia linkii at the GMP site across the autumn and spring 2005 sampling periods. Data represent mean ± S.E. (n = 6) Table 3.3.4. Spring mean densities of prevalent taxa and the proportion within each functional guild on Danthonia linkii

Guild Taxon Spring mean densities* Proportion/guild Aphids (non-specified)# 296 32.3% Plague thrips 294 34.0% Rutherglen bug 95.7 10.4%

Pest

Wasps (parasitic) 75.3 34.1% Mites (predatory)^ 28.3 13.3% Brown lacewings 14.7 6.6% Spiders (various) 10.7 4.8%

Beneficial

Haplothrips (predatory) 5.3 2.4% Collembola 1573 79.5% Flies 130 6.5% Mites (non-specified)^^ 62.3 3.2% Thrips (non-specified) ## 14.3 0.7%

Non-target

Note: *Mean of three 20s D-Vac samples per plot. Spring values are the sum of invertebrates recorded from seven sampling periods between Sept. 9 and Dec. 14 2005. # Predominately cotton aphid, Aphis gossypii. ^ Predatory mites from the families; Erythraeidae, Bdellidae, Teneriffidae and Camerobidae. ^^ Mainly Beetle mites (Oribatidae) ##Includes a range of adult thrips (eg, Anaphothrips) and indistinguishable juvenile specimens.

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Guild Taxon Spring mean densities* Proportion/guild Plague thrips 1283 77.3% Rutherglen bugs 121 7.3% Aphids (non-specified) 80.7 4.9%

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Wasps (parasitic) 49.7 18.9% Mites (predatory)^ 35.0 13.3% Spiders (various) 29.0 11.0% Haplothrips (predatory) 17.7 6.7%

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Brown lacewings 6.3 2.4% Collembola 1575 90.9% Flies 94.3 5.5% Mites (non-specified)^^ 23.7 1.4% Thrips (non-specified) ## 15.0 0.9%

Non-target

Note: *Mean of three 20s D-Vac samples per plot. Spring values are the sum of invertebrates recorded from seven sampling periods between Sept. 9 and Dec. 14 2005. ^ Predatory mites from the families; Erythraeidae, Bdellidae, Teneriffidae and Camerobidae. ^^ Mainly Beetle mites (Oribatidae) ##Includes a range of adult thrips (eg, Anaphothrips) and indistinguishable juvenile specimens.

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A comparison of pest thrips on four native grass species and Brassica weeds for the spring period Four thrips species are considered important pests on the NAP. Three introduced species, Western Flower Thrips (WFT), tomato thrips and onion thrips, are vectors of Tomato Spotted Wilt Virus (TSWV), and the fourth, native plague thrips, does not vector TSWV, but is very abundant in spring and inflicts feeding damage (Table 3.3.6). The results indicate that there were significantly more WFT present on Rapistrum rugosum, the brassica weed, than any of the native grasses, (ANOVA, F4, 27 = 21.84, p < 0.0001). There were also significantly more tomato thrips (ANOVA, F4, 27 = 23.31, p < 0.0001) and onion thrips (ANOVA, F4, 27 = 28.56, p = 0012) present on the weeds than any of the native grasses. Plague thrips were the most abundant thrips on all plant species. Brassica weeds and Themeda triandra had the highest plague thrips numbers (ANOVA, F4, 27 = 10.90, p < 0.0001), with relatively lower densities on other two native grass species. Table 3.3.6. Spring mean densities ( SE) per 20s D-Vac of four pest thrips species found on native grass species and brassica weeds

Species Western Flower Thrips

Tomato Thrips

Onion Thrips

Plague Thrips

Chloris truncata 2.5 ± 1.96 b 0 1.33 ± 0.56 b 146.5 ± 34.73b Danthonia linkii 0.67 ± 0.33 b 0.17 ± 0.17 b 0.67 ± 0.33 b 557.83 ± 176.94b Enneapogon nigrans 2.5 ± 0.76 b 1.17 ± 0.65 b 1.17 ± 0.65 b 366.83 ± 161.19b Themeda triandra 1 ± 0.37 b 0.33 ± 0.21 b 0 2008.5 ± 531.49a Rapistrum rugosum 111.33 ± 17.53 a 19.67 ± 0.928 a 68.67 ± 32.03 a 1550 ± 341.01a

Note: Means in each column followed by a different letter are significantly different (p>0.05, Tukey-Kamer HSD test). Spring values are the sums of thrips recorded from seven sampling periods between Sept 9 and Dec 14, 2005.

Discussion This study was conducted to determine whether indigenous native grasses, such as Themeda triandra, Chloris truncata, Enneapogon nigricans and Danthonia linkii are less suitable hosts of invertebrate pests, particularly of WFT, than common brassica weeds, such as Rapistrum rugosum, when grown near horticulture on the NAP. The results indicate that there are significantly more invertebrates (all guilds) on the Themeda triandra. However, the types of pest on the different grass species varied. This is important because certain pests, such as WFT, have greater importance due to their ability to vector TSWV. In this study, the abundance of WFT on brassica weeds during spring 2005 was 100 times higher than on Themeda triandra. The other native grasses species, Chloris truncata, Enneapogon nigricans and Danthonia linkii, also recorded very low numbers, with 40, 40 and 160 times less WFT, respectively, when compared to the brassica weeds. The four native grasses also recorded lower tomato and onion thrips than the brassica weeds. Generally, numbers of pest thrips that vector TSWV were very low or absent on all grasses. Plague thrips were by far the most abundant pest thrips species on all native grasses and brassica weeds. The brassica weeds and Themeda triandra recorded the highest numbers, but the native plants also supported relatively high number of plague thrips. Although they were the dominant thrips species, their importance as pests is reduced because they do not vector TSWV. In regard to other potential pests, the native grasses species, Chloris truncata, Enneapogon nigricans and Danthonia linkii, were harbouring significant numbers of aphids, predominantly, cotton aphid, Aphis gossypii, which feeds on a range of horticultural crops. The brassica weeds also recorded significant densities of various pest aphid species. Currently on the NAP, there is considerable concern regarding the introduction of lettuce aphid into parts of Victoria and its potential spread into South Australia. The known plant host range of lettuce aphid does not suggest native grasses as favourable hosts compared with weeds, such as thistles. However, native grasses require further evaluation to

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determine any changes in risk by supporting pest aphids, and in particular, lettuce aphid, compared with the common weeds found near crops. In this study, beneficial invertebrates were found on both brassica weeds and native grasses, with parasitic wasps, predatory mites, spiders, predatory thrips and brown lacewings the most numerous in the beneficial guild. Generally, the native grasses harboured fewer parasitic wasps, but higher predatory mite, spider and haplothrips densities. It is not possible to estimate the contribution of any of these invertebrates to the control of key pests on the NAP. However, the range on native plants, including specialist and generalist predators, provide interesting opportunities. For example, predatory Erythraed mites found on native grasses are being considered for further evaluation as biocontrol agents for thrips in glasshouses (Tony Burfield, pers. comm.). Further investigations on the beneficial suite of invertebrates on native grasses are warranted. In addition, there is a substantial group of invertebrates classed as non-target. The non-target group represents species of unknown importance, rather than non-pest or non-beneficial. The majority of non-target invertebrates were adult flies and collembola, which are unlikely to impact on nearby horticultural crops. However, some beneficial or pest species may emerge with larger plantings of these native plants. Further studies are required to determine whether some of these invertebrates may contribute to new pest problems or, alternatively, the control of key pests. Interesting areas for further work are the Chirothrips manicatus as a food source for parasitic wasps associated with the control of pest thrips, or generalist predators, during breaks in the cropping cycle.

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3.4. Summary In this study, the determination of the prevalent species on different plants within pest or beneficial guilds has been used to provide insights into potential pest risks, and potential control agents, respectively. However, abundance is only indicative, as the risk to nearby horticultural crops may be weighted by other contributing factors. For instance, plague thrips were by far the most abundant pest thrips, but their impact on horticulture is small compared to Western Flower Thrips (WFT). WFT are considered very important on the Northern Adelaide Plains (NAP) because they are efficient vectors of Tomato Spotted Wilt Virus (TSWV). The abundance of WFT on brassica weeds was up to 300 times higher than on native perennial plants (Maireana brevifolia, Atriplex semibaccata, Rhagodia parabolica), and up to 160 times higher than the native grasses (Themeda triandra, Chloris truncata, Enneapogon nigricans and Danthonia linkii) surveyed. This represents a significant reduction in the presence of this important pest. The native plants and grasses also recorded far fewer tomato and onion thrips, which can also vector TSWV. There were inter-specific differences, with M. brevifolia recording higher onion thrips when compared to the other two native plants. This suggests that these native plants and grasses are poor host to WFT, but it would be prudent to evaluate more native plants to ensure than some species do not harbour higher numbers of WFT or other TSWV vectors. In addition, it is still unclear whether some of these native plants and grasses will host other pests that may in time emerge as new problems. The most abundant invertebrates likely to become a pest on native plants and grasses were leafhoppers and aphids, respectively. However, the common weeds in the area would also harbour significant populations of these potential pests. The saltbushes, in particular, A. semibaccata, require further evaluation to determine whether they present a greater threat by supporting leafhoppers than the current weeds near crops. It may be possible to manage the threat by growing A. semibaccata in a mixed sward with other native species. Careful plant selection may allow A. semibaccata’s vigorous spreading habit to colonise early and out compete many weeds, but then be rapidly succeeded by more erect native plants. In regard to other potential pests, the native grasses species, C. truncata, E. nigricans and D. linkii, were harbouring significant numbers of aphids. There is considerable concern regarding the introduction of lettuce aphid into parts of Victoria and its potential spread into South Australia. The known plant host range of lettuce aphid does not suggest native grasses as favourable hosts compared with weeds, such as thistles. However, native plants and grasses require further evaluation to determine whether they present a greater threat by supporting pest aphids, and in particular, lettuce aphid, more than the common weeds found near crops. Weeds harbour beneficial invertebrates, but the presence of key pest thrips negates any benefits. In contrast, native plants and grasses harbour more diverse beneficial invertebrates and fewer WFT, which may provide a relative benefit. However, species composition (eg. generalist brown lacewing or specific parasitic wasp) may be more important than overall beneficial abundance. The species composition for different plants indicates that parasitic wasps, predatory mites, spiders, predatory thrips and brown lacewings are the most numerous in the beneficial guild. Further investigations on the beneficial suite of invertebrates are warranted. In particular, parasitic wasps associated with the control of thrips, predatory Erythraed mites found on native grasses, and brown lacewings for potential in IPM strategies to control lettuce aphid. In addition, there is a substantial group of invertebrates classed as non-target. The non-target group represents species of unknown importance, rather than non-pest or non-beneficial. It may be that many of the species will not impact on nearby horticultural crops. However, some beneficial or pest species may emerge with larger plantings of these plant and grass species. Interesting areas for further study include, evaluation of the taxonomy and host preference of whitefly found on Rhagodia parabolica, the diversity of coccinellid species on the native grasses and Rhagodia parabolica, and Chirothrips manicatus as a host for parasitic wasps associated with the control of pest thrips, or generalist

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predators, during breaks in the cropping cycle. In addition, larger stands of native plants and grasses established near horticulture should be monitored to ensure that potential new pests or plant host shifts of existing pests are detected early. Overall, the results suggest that a reduction in the key thrips species may be possible. However, it would appear that the native species chosen in these trials have a range of agronomic and host specificity characteristics that can influence IPM outcomes; in both beneficial and potentially undesirable ways. Further, cultural practices, such as mulching, can also greatly influence the invertebrate composition and abundance on plants (G Wood, unpublished data). This confirms the concept of informed and deliberate plant choice, which we collectively refer to as ‘revegetation by design’. In addition, further work should include the evaluation of currently selected native species over several seasons, and in larger ‘property level’ stands, and the evaluation of additional native species for specialist applications, such as road verges and waste-water ditches.

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4. Characterisation of flowering of weeds and native plants with seed formation and management practices of profitable native plants on the Northern Adelaide Plains Introduction A key challenge for natural resources management is the integration of native revegetation into broader land use priorities. It is well recognised that for revegetation to occur, there needs to an incentive for landholders. Perennial native plants that generate profit are most likely to present a reasonable prospect to engage growers to revegetate threatened land that is under commercial production. In addition native plants can provide refuge, food, breeding sites and over wintering shelter for beneficial insects that is separate from the harshness of rotational cultivation, harvesting and applications of pesticide associated with agriculture. However, it is well known that adult and larval pest thrips and insects are attracted to flowers and pollen and feed on immature fruit and plant tissue. For commercial growers to be confident in their revegetation choices, the relative risks and benefits that weeds and/or native plants could pose to their crops needs to be understood and addressed. The native plants that are indigenous to the Northern Adelaide Plains (NAP) and have the added benefit of potential commercial value will be preferred by growers. Species from within the families Chenopodiaceae, Mimosaceae and Myrtaceae have commercial value in the revegetation industry as seeds, bushfood and the cut flower industry (Horsman and Delaporte 2002). Several indigenous saltbush1 species are favoured for their low growth habit, salt tolerance, low water requirement and high demand for their seeds for direct sowing of revegetation sites. Two local acacias2 have value as bush food and in the floral industry. The Elegant wattle, Acacia victoriae is considered to be one of the most promising species for wattle seed production. This acacia is indigenous to the area, is salt and drought tolerant and has a lifespan of 10 to15 years. In addition this species is listed as a host plant for the lycaenid butterfly Jalmenus lithocroa that is rarely seen now as numbers of this wattle diminish. Acacia baileyana (purpurea) has deep purple foliage that enjoys intermittent demand from the cut flower industry for floral arrangements as ‘filler’. These small, fast growing trees can be used as a farm windbreak and will succeed in most soils and climatic types but do prefer moderately well drained soils. Three genera from the Myrtaceae3 may be suitable for the

1 Salt bush species are from the Chenopodiaceae and occur as herbs or shrubs, are often succulent with compact inflorescences, and have small flowers and fruit that is sometimes succulent or woody. They are cosmopolitan with over 100 genera and 1,500 species; frequently found in saline environments (Black 1986). 2 Acacias come from the Mimosaceae and occur as shrubs or trees with leaves either divided or reduced to phyllodes. The flowers are organised into inflorescences that are made up of numerous small flowers ranging from bright yellow to creamy white and the seed-pods contain a tough flat seed with an aril. They are widespread with over 600 species in Australia and dominant in arid and semi arid regions. Acacia species are generally short lived but some such as the western myall (Acacia papyrocarpa Benth.) can survive several hundred years. 3 Muntries (Kunzea pomifera) is a prostrate semi upright shrub that occurs along the southern coast of Australia is a popular bush food, producing a wild spicy-apple flavoured berry, one centimetre in diameter (Hele 2001). Blue Mallee or Tallerack (Eucalyptus tetragona syn. pleurocarpa) has large bluey grey leaves, glaucus stems and fruit and is considered one of the most popular eucalypts presently grown for export. Curly mallee or Silver Mallee (E. gillii) has gray-blue leaves and attractive fruits and is also considered among the best bet exports. Broombrush baeckea (Baeckea behrii) also has potential for the floral industry, being a 1-2.5 meter tall shrub

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NAP, Kunzea pomifera, a bush food, and Eucalyptus tetragona, E. gillii and Baeckea behrii that are all cut flowers. We characterised flowering times of key weeds and selected native plant species on the NAP to determine when pests and beneficial insects are likely to be attracted to these plants. Seed production from established plots of native plant species, and collection methods for seeds were evaluated to give some insight into their relative commercial value and ease of seed collection, respectively. Materials and methods Sampling A regional (greater Northern Adelaide Plains area) survey of weeds and native plants was conducted fortnightly between March 2003 and 2004. Nineteen species of weeds most common on the Northern Adelaide Plains were selected for flower characterisation from families including Brassicaceae, Asteraceae, Borginaceae, Portulacaceae, Chenopodiaceae, Oxalidaceae, Solanum, Zygophyllaceae, Apiaceae, Polygonaceae, Aizoaceae and Malvaceae. Voucher samples of weeds were collected, pressed and identified using keys by Wilding et al (1993), Moerkerk and Barnett (1998) and Lamp and Collet (2002). Fifteen native plant species from genera within three families within the Chenopodiaceae (saltbushes), Mimosaceae (acacias) and Myrtaceae were selcted for flower characterisation. The saltbushes and Acacia victoriae were present as remnant vegetation or in City of Playford seed orchards on the Northern Adelaide Plains. The eucalypts and Acacia baileyana sampled were growing as part of the Laidlaw Plantation at the Waite campus of the University of Adelaide. All of the Atriplex species, Enchylaena tomentosa, Rhagodia crassifolia and R. parabolica were planted in woven plastic weed-mat to evaluate the ease of collection of seeds. Flowering was characterised according to the following procedures: Ephemeral weeds were located by driving around the NAP for two days per fortnight searching for plants with flowers visible from the roadside or at the native vegetation sampling sites. Flowers were noted and collected into flower funnels for thrips analysis (see Chapter 2). If enough flower units to fill a 70 ml container could be taken from up to five random plants the weed species was classified as flowering and the date recorded. Native plant collection sites were already established with previously identified plants. The criteria for flowering were the same as for weeds. Seed set period for native plants was defined as first fruit set through to seed fall and was recorded at the same time as flowering assessments. To assess seed production, saltbush seeds were collected into paper bags and allowed to dry. Seeds were cleaned using graded sieves, then weighed and stored in calico bags. We did not collect the seeds or fruits of the Mimosaceae or Myrtaceae species, concentrating instead on the Chenopodeaceae that were being evaluated on the weed mat. While flowering occurred on the acacias and eucalypts that were surveyed, seeds were not taken, as the trees were roadside vegetation remnants or part of a plant breeding experiment, respectively. Kunzea pomifera is a long-lived species that may not fruit for several years. While these fruits can be collected as seed they are of little value as this species is best grown from cuttings. The Kunzea pomifera at our collection sites were newly established and no seed had been produced for collection. Results and discussion Flowering Weeds from a range of species were continuously flowering on the NAP. For instance, flowering turnip weed, blanket weed, fat hen and mallow were constantly present (Table 4.1). Several of the

with erect branches with fine pointed leaves and small flowers that are similar to thryptomene and geraldton wax.

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weeds that are normally annuals were persistent throughout the year on grower properties and their extended flowering season may be explained by their common presence within irrigated crops. Generally, the brassica species suite flowered during spring and autumn coinciding with the horticulture production seasons. Other weedy species such as sour sob, nettle and scotch thistle were not flowering in autumn. Saltbushes generally had extended flowering times through spring, summer and autumn but not winter (Table 4.2). Some taxa had a shorter flowering period for instance Atriplex cinerea, that flowered in spring and early summer and Maireana brevifolia that flowered late summer and early autumn. The acacias and myrtaceae had shorter flowering periods of up to eight weeks. However, Eucalyptus gillii flowering extended over eight months, possibly as some of the trees were hybridised with other eucalypts growing in the extensive Laidlaw Plantation on the Waite campus where they were sampled. It is important to know the species of pest thrips virus vectors that can be expected for each of the weed or native plant flower unit on the NAP. It is also critical to know the timeframe for flowering of weedy host plants across the landscape as this indicates when growers are likely to experience pest pressure. Flowering plants are attractive to a range of insect species. On the NAP, the attractiveness of flowering plants to pest thrips (such as western flower thrips), and the diseases they vector, such as tomato spotted wilt virus, is very important to growers of susceptible horticultural crops. The constant presence of flowering weeds on the NAP that potentially offer highly visible floral resources to insects, especially pest thrips, represents a legitimate concern for the horticulture industry. Neglected fields filled with seasonal weeds, for example brassica weeds, can act as a reservoir for pest thrips that vector disease. In addition, brassica weeds that can grow and flower year round in irrigated crops can act as a ‘green bridge’ for these vectors to infect new crops, regardless of the season. In contrast, the native flowers of plants from the Chenopodeaceae, Myrtaceae and Acacia are flowering for a relatively short time compared to weeds, and are less likely to be responsible for attracting large numbers of exotic pest thrips. This study indicates that native plant species are usually flowering for a shorter period during the year than weedy species. Despite the ephemeral nature of weeds, there appears to be sufficient irrigated areas to support flowering plants all year round. This suggests that native plants may be less attractive, and perhaps, less suitable, as hosts for important pest thrips. No attempt was made to determine the relative attractiveness of flowers, but the inconspicuous nature of many native species’ flowers suggest that they may be less attractive to flower thrips. Further investigation into the relative attractiveness of different flower types to key pests should provide greater insights into the risks of various flowering plant species.

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Table 4.1. Flowering times of common weeds sampled on the greater Northern Adelaide Plains 2003-4 Species Common name June July Aug Sept Oct Nov Dec Jan Feb March April May Azioaceae Galenia pubescens (Eckl.&Zeyh.) Druce Blanket weed Asteraceae Arctothea calendula(L.) Levyns Cape weed Sonchus oleraceus (L.) Sow thistle Cirsium vulgare (Savi.) Ten Scotch thistle Brassicaceae Raphanus raphanistrum L. Wild radish Rapistrum rugosum (L.) All. Turnip weed Diplotaxis tenuiufolia (L.) DC Sand rocket Sisymbrium orientale L. Indian hedge mustard Boraginaceae Echium plantagenum L. Salvation Jane Chenopodiaceae Chenopodium album L. Fat hen Malvaceae Malva parviflora L. Mallow Oxalidaceae Oxalis pes caprae L. Soursob Polygonaceae Polygonum aviculare L. Wire weed Portulacaceae Portulaca oleraceae L. Portulaca Solanaceae Solanum nigrum L. Black nightshade Solanum elaeagnifolium Cav. Silverleaf nightshade Umbelliferae Foeniculum vulgare Mill. Fennel Urticaceae Urtica urens Nettle Zygophyllaceae Tribulus terrestris L. Calthrop

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Table 4.2. Flowering times of native plants sampled on the greater Northern Adelaide Plains 2003-4 Plant Species June July Aug Sept Oct Nov Dec Jan Feb Mar April May Chenopodiaceae Atriplex semibaccata(R,Br) Creeping saltbush Atriplex suberecta(I.Verd) Lagoon saltbush Atriplex padulosa(R. Br) Marsh saltbush Maireana brevifolia(R. Br) Small leafed saltbush Rhagodia parabolica(R. Br) Mealy saltbush Rhagodia crassifolia(R. Br) Scented saltbush Rhagodia candolleana(Moq) Sea Berry saltbush Enchylaena tomentosa(R. Br) Ruby saltbush Mimosaceae Acacia victoria(Benth) Elegant wattle Acacia baileyana(F. Meull) Cootamundra wattle Myrtaceae Kunzea pomifera(F. Meull) Muntries Baeckea behri(Schldl)F.Muell Silver broom E tetragona Eucalyptus gillii Curly mallee key flowering period flowering + seeding / fruiting winter spring summer autumn seeding / fruiting period neither occuring

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Seed development and collection The majority of species in the weed mat trial produced seeds or fruits in late summer and autumn (Table 4.2). The seed production on selected plots established during this project can be seen in Table 4.3. Table 4.3. Seed yield and price per kilogram for native plants that produced a saleable quantity of seeds.

Species Wt (kg)* 2004 Wt (kg)* 2005 Price/kg Atriplex semibaccata 8.5 2.5 $60 A. suberecta 2.3 0.15 $40 Enchylaena tomentosa 7.0 4.5 $125 Maireana brevifolia 0.1 0.05 $80

Note: *All plots were the same size (63 m2) and contained 36 plants Atriplex semibaccata and A. suberecta produced seed prolifically but had a limited life-span on the weed mats, for the most part bursting out, and in the case of A. suberecta, dying back within the space of a single season. Half of the A. semibaccata plants endured from 2004 to 2005 (with a reduced seed-yield). These species may be best managed simply by pulling out the older plants after first season seed-set to allow the seeds that have fallen into the hole in the weed mat allocated for each plant to germinate and occupy the old plant’s previous space. Enchylaena tomentosa, planted in 2003, has thrived continuously on the site, producing prodigious quantities of seed in both 2004 and 2005. Since the extensive flooding and prolonged inundation of the site in November 2005, the plants have overgrown their section on weed-matting, forming a dense, impenetrable mat of branches intertwined with silt at their bases, considerably hampering the efficiency of weed-mat seed production. Ideally, these plants should be grown for only two seasons on weed mats and then replaced. For Enchylaena (and the Atriplex species) it is necessary to avoid allowing seed to be soaked by autumn rains (rare on the NAP), as they may begin to germinate and become mouldy, although a small amount of moulding does not appear to hamper subsequent germination. Maireana brevifolia seed [actually a light winged fruit] production was prolific, but this wind-borne species can be difficult to collect and dry seeds that will detach themselves from the parent are often frustratingly sparse given the sheer volume of fruiting material on the plants. It should be noted that M. brevifolia seed need to be sown or direct seeded within a few months of collection, as it has exceptionally little viability after storage. Rhagodia species have fruits that are physically held aloft and wither on the plant, and are best harvested straight from the terminal ends of the branches. There is little seed-collection value in placing this species on weed mat. R.crassifolia flowered but did not produce many seeds and is not a species recommended for seed production on weed mat (Murray 1994). Collecting off weed mat produces clean seeds easily for the prostrate Atriplexes and Enchylaena that are prolific seed producers, with the qualifications noted above. While the Rhagodias can be grown on weed mat, this is not necessary and these plants may provide a better option where weed mat is not indicated. Growers observing seed production and collection at open days have indicated genuine interest towards growing and selling seeds from these native plants. Growing seeds on weeds mat for revegetation programs would give them an opportunity to use less productive land to derive additional income from seed sales. Most growers were impressed with the Eucalypts with the cut buds in the first season approaching market quality. Eucalyptus tetragona syn pleurocarpa and E. gillii pose minimal risk of harbouring crops pests and have been evaluated as being in the top 15 species for cut bud, flowers and capsule production (Horsman and Delaporte 2002). However, some plants will not be suitable for the NAP and

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although Baeckea is now considered as having potential as a viable wildflower crop in suitable parts of temperate Australia (Slater 1990), this species requires well-drained acid soil and is unlikely to grow well. In addition, Acacia baileyana was evaluated at the Waite arboretum, however, it was decided not to plant this species in our trial plots as it is a rapid coloniser and is considered an environmental weed in the NAP.

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5. Direct seeding trials of three native grasses Chloris truncata, Enneapogon nigricans and Austrodanthonia linkii (fulv) in a horticultural context on the Northern Adelaide Plains Introduction

There are almost no remnant stands of native grass species remaining on the Northern Adelaide Plains (NAP) and revegetation with tube stocks are labour intensive and plantings are expensive at the property scale. In addition, there is little commercial incentive for local horticultural growers to invest in planting native grasses.

Direct seeding can offer a cost effective and efficient method for creating stands of native grasses that suppress weeds, reduce erosion, improve biodiversity and potentially provide a refuge for insects beneficial to horticulture. However, land that is not used for production and could be available for revegetation near commercial crops is generally not of high enough quality for growing crops, is often compacted and has a long history of herbicide application for weed management. In addition, native grasses can often have specific requirements for germination and the technology for seed cleaning and direct seeding is in the early stages of development.

It is also important to choose native grass species that have appropriate agronomic characteristics and are climatically suited to the area. Chloris truncata and Enneapogon nigricans are a summer growing (C4) species that commonly occur in the Virginia district. They have some tolerance to glyphosate and are often found growing on road shoulders where they take advantage of summer rain that runs off the sealed carriageway. Being of relatively low height, both species were considered ideal for planting on horticultural premises where they would provide groundcover with minimal fire risk and not shade crops in the greenhouse. The winter growing (C3) Austrodanthonia spp. responds well to the predominant winter rains.

This study aimed to measure the establishment of three native grass species by direct seeding and evaluate the potential of direct seeding for revegetation near commercial crops on the NAP. Materials and Methods Sites and site preparation Trial 1: Chloris truncata and Enneapogon nigricans 2003 Direct seeding trials using mixtures of two native grasses Chloris truncata and Enneapogon nigricans were made in September 2003 adjacent to commercial horticulture in properties on corner Old Port Wakefield Road/Angle Vale Road (Site 1) and Womma Road (Site 2). The native grasses were machine sown within 3 meters of greenhouse crops on both horticultural properties. Both trials were sown at a combined rate of 4 kg seed per hectare and the plots measured 20 X 90 m (1800 m2) and 5 m X 110 m (550 m2) respectively. To minimise weed germination, physical disturbance of the soil was avoided when preparing the ground for sowing. Glyphosphate at 2.5 litres plus 0.1 litre of Oxyflurofen per hectare was used to spray existing weeds. Oxyfluorfen was added as a spike to gain better control of marshmallow (Malva parviflora) that is common in the district when under a glyphosate spray regime.

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Trial 2: Autrodanthonia linkii (fulv) 2004 The largest trial area planting was made in the City of Playford, Virginia Gateway Reserve on the corner of Port Wakefield Road and Old Port Wakefield Road (Site 3). Autrodanthonia was machine sown at 5.4 kg per hectare as 11 mid-rows within the display orchard averaging 39.7 m in length. With an effective 2.29 m sowing width this amounted to approximately 1000 m2 (5 rows of grass per mid-row at 46 cm apart). With minimal disturbance to the soil, Glyphosate (360 g per litre product) was used at 6 litres per hectare to control a range of hard-to-kill weeds on the site to be sown with Austrodanthonia. This was applied in May approximately three weeks before the grass was sown in June. A re-sowing of Austrodanthonia was undertaken in grass deficient mid-rows of the orchard in July 2005. Equipment A hydro/pneumatic seed drill was used to deliver cross-linked polyacrylamide added to water at 4.5 gms/litre to produce a fluid capable of holding the seed in suspension. A total of 3 kg of grass seed is added to 200 or 400 litres of the above fluid (dependent on sowing speed) to make up the 3 kg seed mixture per hectare required for sowing. An electrically powered agitator fitted into the cap of a standard 600 litre Hardi spray tank ensured that the seed is evenly dispersed within the mixture. A vane type air compressor, also electrically operated, assisted in displacing the seed mix from the airtight vehicle-mounted tank. A peristaltic (hose) pump, mounted on a trailer and powered by a small petrol engine via an electric clutch and gearbox, ensured that the seed mix is delivered at equal rates via its five hoses. A flexible hose takes the vehicle’s diesel engine exhaust gasses to a manifold alongside the peristaltic pump. Five outlets from this manifold inject exhaust gasses into the delivery hoses of the pump to rapidly carry the seed mix via hoses to the soil that is opened by minimal tillage apparatus consisting of five pairs of converging discs spaced at 458 mm (18 inch) centres. Once the grass crop was established, weeds between the rows of native grass were sprayed using jets fitted with fore and aft shrouds and located in a 305 mm (12 inch) space between twin 610 mm (24 inch) disc coulter assemblies. Spray jets within outrigger shrouds manage weeds outside the first and fifth rows. Inter-row weed control of the Austrodanthonia spp. plantation was undertaken in September and November of 2004 and in June 2005. Further maintenance was to mow the rows of mature plants with a prototype sculpture mower. This machine cuts weeds in between the grass rows at lawn height and crops the native grass to a height of 305 mm (12 inches). Results

Trial 1: No germination of Enneapogon nigricans and Chloris truncata was observed throughout the warm spring/summer/autumn period of 2003/2004. After the winter break rainfall 2004, occasional Enneapogon nigricans and Chloris truncata plants (less than 10) were seen at site 2.

Trial 2: Inspections conducted 1 and 2 months after sowing revealed that germination of Austrodanthonia spp. was poor with most plant germination occurring at the northern end of the trial site. In addition to the very poor germination rate, it was likely that plant losses were occurring over subsequent months. In July 2005 a plant count was taken of all Austrodanthonia spp. plants occurring in the 55 (11 x 5) rows sown. Whereas an average of 10 plants per lineal metre in the rows might have been expected, the best achieved was 1.8 plants/metre (Fig. 5.1). Post sowing maintenance with sculpture mowing was not evaluated on such low grass numbers.

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Austrodanthonia plants at Site 3

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64

Row number

Plan

ts/m

eter

Figure 5.1. The average number of Austrodanthonia plants established per lineal metre in rows sown for Trial 2 in the demonstration orchard Site 3, July 2005 (n=55 rows scored)

Discussion Overall the native grass germination rates were poor. Almost no germination at sites 1 and 2 may be attributed to the fact that there was no suitable rain during that period. The pattern of arrangement of the occasional Enneapogon nigricans seen appeared to adhere to the original row design and it is possible that some seed persisted and germinated in the following spring as a result of the winter rains. Enneapogon nigricans and Chloris truncata depend on continuing spring rains and/or a substantial summer rain (i.e. a 60 mm rain event) to facilitate germination in the warmer weather. Chloris truncata is known to require exposure to continually wet soil for 3 to 4 days under mild to warm conditions before it will germinate. It is not unusual for these C4 grasses to rely on summer-rain events spread at 3 to 4 year intervals to germinate. While the lack of summer rain was an obvious reason for the zero response from the C4 grasses, there is no guarantee that results would have been any better with the rain. A long history of cultivation, fertiliser application, irrigation and soil compaction has severely modified the soils at Virginia since the days when they once supported native grassy woodland. Growth at site 3 was patchy, with poor germination and survival demonstrated with a focus of growth at the northern end of the site. It is difficult to say whether low plant counts were due to low germination success or loss of recently germinated seedlings due to insect or environmental damage. Austrodanthonia spp. normally germinates after approximately 14 days of being sown and subjected to moist soil at the beginning of winter. Soil structure may have influenced germination. For instance, wet and heavy clay soils are noted for their inability to accommodate direct-seeded native grasses, having lower native grass germination, and post-germination survival rates. Any departure from a healthy, well-drained aerobic soil towards an anaerobic soil with its associated poor soil structure, poor drainage and imbalance of nutrients, may inhibit native plants. Also, there is some indication that native grasses tend to perform better in soil that has previously grown grass of the same species (John Stafford, unpublished 2003). It remains likely that Austrodanthonia spp.is an appropriate species as it has given good germination and better growth rates than other species of this genus when

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sown in adverse soils. For example, Austrodanthonia spp. “linkii” sown at Nuriootpa research Centre, SA Water at Mt Pleasant and at Birdwood South Australia performed much better than Austrodanthonia geniculata sown on the same properties (Stafford unpublished data 2004). While there is growing interest in replacing introduced broadleaf weeds with indigenous plants that harbour few crop pests, soil quality is likely to be a determining factor in how establishment of native grasses is achieved. The direct drilling of native seed remains an economic method of establishing native plants on a broad scale with some success in direct seeding native pastures. However, there remains unresolved issues such as seed sourcing1 and machine delivery2 facing those who wish to use direct sown native grass to suppress pests in horticulture and promote the ‘right’ biodiversity. This study suggests that a better understanding of the market garden soils in the Virginia horticulture area and their relationship to native species will be necessary to deliver the final outcome.

1 Most conventional seed drills can handle seeds that are cleaned down to the caryopsis, or grain. However, the cleaning of native floret seed has caused technical problems. Each genus has florets with different characteristic structures and requires different machinery to handle them. There is a priority to maintain the genetic integrity of native species within regions in South Australia, the requirement is to establish seed of local provenance and the modest volumes involved do not justify the expense of developing the machinery to clean it. As a result, the seed cleaning industry for native grasses is still in its infancy and clean seed can be either prohibitively priced or not available. 2 There has been progress towards solutions to machine sowing of native grasses. In this study a hydro/pneumatic seed drill that uses one convenient medium to carry the diversity of floret seed associated with native grasses has been designed and used. Post-sowing maintenance using a new machine that cuts grasses to promote larger tussocks may have some potential. It has the effect of encouraging the native grasses to develop an optimum root mass to compete more effectively with closely mown weeds.

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6. Pollen as a marker: using Scanning Electron Microscope (SEM) images to describe the movement of the native brown lacewing Micromus tasmaniae on the Northern Adelaide Plains Introduction Information about the presence of insect predators and parasitoids on non-crop plant species in the crop and surrounding landscape is useful for pest management. However, any attempt to determine the influence of those naturally occurring beneficial insects on neighbouring crops requires an understanding of the spatial and temporal dynamics of their movement. Greater understanding in this area may lead to the development of IPM strategies that include native vegetation as sources of beneficial insects that can move into nearby crops. To track the movement of beneficial insects, pollen has the potential to be a good “natural” diagnostic marker. Pollen is comprised of sporopollenin (Faegri et al.1989) it is hardwearing, able to maintain shape and character (Kearns & Inouye 1993), can adhere to the exoskeleton of foraging insects and has morphologically distinct characters (Silberbauer et al. 2004). This feature enables pollen to be a potentially useful marker to track movement, dispersal and habitat usage for beneficial insects (Silberbauer et al.2004). Scanning electron microscope (SEM) analysis has been shown to be an accurate method to characterise pollen architecture and exine patterns (Lanza et al.1996; Sedgley et al.1993). SEM pollen analysis has been used to investigate its effectiveness as a tool for studying the movement of pest and beneficial insects (Silberbauer et al. 2004; Silberbauer & Gregg, 2003; Del Socorro & Gregg, 2001; Gregg 1993). The technique is useful when known pollen types are used. However, pollen from many plants, particularly from Australian native species, have not been characterised by SEM analysis. The aim of this study was to assess short-term movement and habitat usage of beneficial insects within the landscape of the Northern Adelaide Plains (NAP) using insect-borne pollen. The brown lacewing, Micromus tasmaniae was used as a model to evaluate the distance that beneficial insects are likely to forage. The study also aimed to provide a library of digital SEM pollen images collected from flowering plants to provide morphological reference material for comparison with insect-borne pollen. Materials and Methods Sampling Sites To evaluate their movement within the landscape of the NAP brown lacewings (Micromus tasmaniae) and Nabids (Nabis kingbergii) were collected from native vegetation and weeds either >100m from a crop or within <10m from a crop. Between August 2003 and April 2004 a sub set of insect Dvac samples from Maireana brevifolia, Rhagodia parabolica, Atriplex semibaccata, Acacia victoreae, Enchylaena tomentosa and Eucalyptus tetragona were selected from seven sites; method is described in Chapter 2. In spring of 2005 a second subset of lacewings was collected at the Greenhouse Modernisation Project (GMP) main trial plot; method is described in chapter 3.1. Insects were removed from samples and stored at –20o C in airtight containers to process for SEM imaging.

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From the two survey periods a total of 24 adult brown lacewings and two adult nabis insects were processed for SEM analysis. In addition, each specimen from the second survey season (spring 2005) was dissected into seven body parts (fore wings, hind wings, legs, thorax/abdomen, head, antennae and mouthparts) which were then mounted onto SEM stubs covered with double-sided adhesive tape. Reference pollen material from 30 flowering plant species on the Northern Adelaide plains was collected in paper envelopes. To release the pollen grains, anthers were gently squashed with fine forceps onto SEM stubs covered with double-sided adhesive tape. All samples were coated with Platinum (3-6 nm) using a high-resolution sputter coater (Cressington 208HR). One lacewing sample (L3 from the GMP4) was coated with carbon-gold (3-6 nm). Examination of SEM samples Digital images of the insect exoskeleton bearing pollen were captured and each insect was ranked according to the number of different morphospecies of pollen present. Pollen on all lacewings captured at the GMP during spring 2005 was recorded from individual body parts. A further three lacewings collected from the GMP were not completely examined but their mouthparts scores are included into mouthparts assessments. Samples were examined at a minimum of 400X and imaged using secondary electrons in a Philips XL30 field-emission gun scanning electron microscope (SEM). For all samples examined the accelerating voltage was 10kV, spot size was three and working distance was 10mm respectively. SEM images of pollen taxa from the reference collection and the lacewing survey were scored as spherical, ovoid, semi ovoid, or triangular in shape. In addition diameter or length and width were measured and means calculated (when possible) using the image analysis software program AnalySIS® (Soft Imaging system GmbH©1998, Germany, website www.soft-imaging.de). A review of journal and web-based literature was conducted and a collection of scanned and digital pollen images developed to provide morphological reference material for comparison with insect-borne pollen. We created a catalogue using digital images grouped as thumbnails that could be easily and quickly used for identifying differences between pollens on scanned insects. The pollen reference collection was used as a guide for identification of digital pollen images from this survey. Pollen shape, surface texture, pattern and size range (10 – 50 µm) were recorded for each morphospecies (pollens with unique and distinct morphological differences). Taxa were considered to be of fungal origin5 and omitted from subsequent analysis if; (i) it was club-shaped or ovoid and highly tapered or (ii) less than 10 µm regardless of shape and surface texture. Nineteen unknown taxa were considered to be of fungal origin and were omitted. Local lacewing movement from host plant (GMP) Lacewings (n=10) captured at the GMP in spring 2005 were used to assess movement within the landscape. Where pollens observed on the lacewings could be identified, minimum distances (in meters) from host plant to the closest possible known plant visited was measured. Results A total of 18 pollen morphospecies (eight known and ten unknown) were identified on the 24 lacewings examined. The known pollens were from the plant families Poaceae, Myrtaceae, Malvaceae, Brassicaceae, Asteraceae, Chenopodiaceae, Azioaceae and Goodeniaceae. 4 Greenhouse Modernisation Project (GMP) – the major demonstration site containing trial plots of native plants and grasses. 5 Classification based on information provided by Fele Hopf and David Schmeil (Pollen palynologists), Eileen Scott (Fungal taxonomist), Trevor Wicks and Barbara Hall (Plant pathologists).

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Figure 6.1 shows the total number of different pollen morphospecies observed per lacewing (n=24) selected from a range of plants species on the NAP. The highest pollen morphospecies recorded was eight on a lacewing collected from Chloris truncata followed by the lacewing collected on Goodenia ovata with a total of seven. All other lacewings surveyed ranged from two to six pollen morphospecies. The two nabids examined in this study bore a total six and five pollen morphospecies respectively.

0

2

4

6

8

Brassica w

eeds

Chloris truncata

Danthonia linkii

Danthonia linkii

Enneapogon nigricans

Themeda triandra

Rhagodia crassifolia

Rhagodia parabolica

Rhagodia parabolica

Atriplex suberecta

Atriplex suberecta

Atriplex sem

ibaccata

Atriplex sem

ibaccata

Atriplex sem

ibaccata

Maireana brevifolia

Eucalyptus tetragona

Eucalyptus tetragona

Eucalyptus gillii

Eucalyptus gillii

Acacia baileyana

Galenia pubescens

Enchylaena tom

entosa

Goodenia ovata

Olearia ram

ulosa

Plant type

No.

pol

len

mor

phos

peci

es

Figure 6.1. Total number of different pollen morphospecies observed on brown lacewing Micromus tasmaniae (n=24) collected from weeds and native species on the Northern Adelaide Plains (2003-2005) The results from brown lacewings collected over the NAP indicated that regardless of host plant and location, greater than 80% (20) of the lacewings sampled visited Malvaceae. Malvaceae was the only known pollen found on the mouthparts of the lacewings surveyed. Seven (~30%) of the lacewings surveyed visited Myrtaceae. Seven (~30%) of lacewings scored Chenopodiaceae pollen, though only two of these were not collected from a Chenopodiaceae host plant. Nine (~40%) of lacewings recorded Brassicaceae pollen, four (~17%) recorded Asteraceae and three (~13%) recorded Galenia pollen. Goodenia ovata pollen was present only on the lacewing collected from this host plant. The results for the 10 lacewings collected at the GMP showed that six (60%) visited Brassicaceae (weeds) and eight (80%) lacewings found on native grass bore native grass pollen. The diversity of pollen morphotypes varied according to the body part: 71% of the total pollen morphospecies were found on the forewings, 64% on the legs, and 57% on the hind wings. The body and head recorded 35% of the total pollen morphospecies, the antenna recorded 28% and mouthparts 14%. Based on known pollens, legs scored slightly more weeds species pollens, specifically, from the Malvaceae and Brassicaceae families. There was no difference between the number of pollen morphotypes from the Myrtaceae family found on lacewing thorax/abdomen, legs, fore and hind wings.

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We scored a similar diversity of fungal morphospecies (19) and pollen morphospecies (18). Of the 19 fungal morphospecies, three were dominant and present on 83%, 67% and 58% of all lacewings surveyed (n=24). The most dominant fungal morphospecies was also scored on 42% of the mouthparts surveyed (n=12) from the GMP. A key interest in this study is the distance lacewings could travel to collect the different pollen morphospecies. Table 6.1 shows the minimum distance from host plant to visited plant groups for seven lacewings captured at the GMP. From known pollen morphospecies, we were able to observe some local scale movement and habitat usage. The largest minimum distance that a lacewing was observed to travel from the host plant R. crassifolia was 32.5 m to visit Galenia. Between native species, one lacewing from native grass Themeda had travelled at least 24 m to a Myrtaceae. In addition two lacewings collected on Chloris and Danthonia had travelled at least 16 m and 17 m respectively to visit the closest Myrtaceae situated on the edge of the GMP. Lacewings had travelled at least 8.5 m to 22 m to visit Malvaceae plants that were on the edge of the GMP property. Lacewings that visited Brassicaceae were required to travel less than 13 m. With the exception of one lacewing (from R. parabolica), all other lacewings bore pollen from their host plant. Table 6.1. Minimum distance (meters) from host plant to visited plant species for Micromus tasmaniae captured at the GMP (n=7) Distance between host plant and visited plant (m)

Date collected Host plant Myrtaceae

spp. Malvaceae

spp. Brassicaceae

(weed) Galenia

pubescens 21/10/2005 Brassica weed 13 30/11/2005 Chloris truncata 16 22 13 30/11/2005 Danthonia spp 17 14 8 30/11/2005 Enneapogon nigricans 18 30/11/2005 Themeda triandra 24 8.5 6 8/04/2004 Rhagodia crassifolia 32.5 21/10/2005 Rhagodia parabolica 21

A library of SEM images of pollen from known plant species was assembled (Appendix, Plates 1-6). A total of six plates containing six pollen grain images per plate were created and pollens were characterised. The pollen species for each plate are as follows:

• Plate 1: native species Atriplex padulosa, A. cinerea, A. semibaccata and A. suberecta (Chenopodiaceae).

• Plate 2: native species Rhagodia crassifolia, R. candolleana, R. parabolica and weed species Chenopodium album (Chenopodiaceae).

• Plate 3: native species Acacia baileyana and A. victoriae (Mimosaceae ) plus Baeckea behri, Melaleuca lanceolata, Eucalyptus gillii and E. tetragona (Myrtaceae).

• Plate 4: native grass species Chloris truncata, Danthonia linkii, Enneapogon nigricans and Themeda triandra (Poaceae) plus native species Goodenia ovata (Goodeniaceae).

• Plate 5: native species Myoporum parvifolium (Myoporaceae) and common weeds Rapistrum rugosum, Raphanus raphanistrum (Brassicaceae) plus Oxalis pes caprae (Oxalidaceae), Echiium plantagenum (Boraginaceae) and Solanum elaegnifolium (Solanaceae).

• Plate 6: common weed species Foeniculum vulgare (Umbelliferae), Galenia pubescens (Azioaceae), Malva sp. (Malvaceae), Sonchus oleraceus and Lactuca serriola (Asteraceae).

The results indicate that Chenopodiaceae pollen is generally not morphologically distinct at genus level, thus native species of Atriplex and Rhagodia species are difficult to distinguish between each other or from the weedy Chenopodium album, common on the NAP. Native plants can look similar to weeds for example Myoporum parvifolium is difficult to distinguish from weedy Brassicaceae, which

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can look similar. On the other hand, some groups such as Acacia have quite distinct in pollen structure and are able to be identified to species level. Poaceae are difficult to distinguish at the genus level in relation to surface texture. However, there were slight differences in size with Themeda triandra being slightly larger on average compared with Danthonia linkii, Enneapogon nigricans and Chloris truncata respectively. Discussion In this study, the total numbers of pollen morphospecies observed on individual lacewings were similar regardless of the host plant or site where they were captured on the Northern Adelaide Plains. At the GMP, lacewings had traversed at least 24m between native plant species within the trial plots area. Lacewings can range further and were observed to visit introduced species such as weedy Galenia pubescens as far as 32.5m away. Unfortunately, this approach does not distinguish the relative attractiveness of different plant species to lacewings. However, native plants species were commonly visited. As such, native plants represent a candidate for refuge and may support early colonisation of mobile generalist predators, such as the brown lacewing, into nearby crops. It is likely that this method underestimated the number of plant species actually visited by the lacewings within the landscape. This could occur for a number of reasons. Firstly, certain pollen types may not persist for very long on the insects. The pollen may not adhere, or may be dislodged within a short period when the pollens are too large or lack pollenkitt (pollen glue). Surface sculpturing of pollen grains (eg presence of spikes) also has an effect on adhesion (Moore et al. 1991). Del Socorro and Gregg (2001) studied the persistence of sunflower pollen (Helianthus annuus L.) on the proboscis of Helicoverpa armigera and suggested pollen to be a transient marker and an indicator of moth movement only of the previous night or two. If this is the case, we have most likely underestimated the ‘lifetime movement’ of the brown lacewings. Other factors that would underestimate total pollen counts on an insect include the variability in flower morphology (phenology) and in pollen loads of native plant species compared to weed species. Although we did not quantify pollen loads in this study, we observed pollen loads of native plants Chenopodiaceae to be relatively lower than Brassica weed species. Chenopodiaceae species are common within the landscape at the GMP yet their pollen was not frequently observed on lacewings (other than those collected from Chenopodiaceae). It would be of interest to further investigate the frequency of pollen type intercepted on lacewings in relation to differences between pollen loads as well as pollen architecture, and pollenkitt strength. The number and type of pollen species found on insects can be dependent on the season that the insects were caught (Silberauer and Gregg 2003) and the local presence of flowering species. There are large costs associated with processing insects for pollen types using SEM. Silberbauer et al., (2004) suggested the use of a subset of body parts could reduce processing time and associated costs. Relevant body parts depend on the insect’s cuticular properties and size, but, generally, small glabrous insects have less pollen than larger and more hairy species (Del Socorro and Greg 2001; Silberbauer et al. 2004). In this study, forewings and legs scored more pollen morphospecies compared to the body (abdomen), which was the most hairy body part of lacewings. Further investigations, are required before recommendations can be made on appropriate body parts for different pollen types. Pollen identification using morphological features can pose challenges. Within many taxonomic groups there is a high level of uniformity in both the size and structure of pollen grain characters via SEM images. Sedgley et al. (1993) found a high level of consistencies between species and between groups in Banksia pollen grains compared to the pollen presenter structure. Our study indicated that many pollens were not distinctive even at the genus level, which was a problem for separation of some native plant species.

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The lack of morphologically distinct pollen characters for native grasses may not be a concern for insect habitat usage and movement studies, as they are wind pollinated and are likely to be distributed within the landscape. In addition, pollens can be considerably misshapen making identification extremely difficult. Other factors that obscured surface and taxonomic features included debris adhered to pollen, orientation on insect (specimen manipulation is limited with SEM) and hydration versus dehydration, which seemed to be an issue for native grass pollens. Non-pollen spores can make processing and allocation of morphospecies time consuming and costly. Lacewings carried a high load of non-target material that included petals, anthers and fungal spores. Overlapping size variations makes pollen very difficult to distinguish from fungal spores and fruiting bodies. Assessing unknown pollens versus unknown fungi requires taxonomic expertise in both fields. In this study, we scored a similar amount of pollen and fungal morphospecies. A dominant fungal spore morphospecies was found on all lacewings surveyed implying that their distribution is wide spread over the Northern Adelaide Plains. In addition, we found nearly half of the lacewings from the GMP carried fungi on their mouthparts, which indicates they are directly eating the fungi or are foraging on contaminated plant species. Yee (1998) examined ingested pollen in four species of generalist predators in cotton, which included M. tasmaniae. The gut contents of adult M. tasmaniae indicated that they are omnivorous and feed on arthropods, pollen and fungi (Yee 1998). This study has made a significant contribution and provides a solid foundation for future pollen analysis via SEM images of the NAP. A regional pollen reference collection will ameliorate some of the difficulties we experienced in identification of unknown pollen groups. There is still a lack of Australian SEM pollen databases for comparison, and we would recommend further work in this area. Further, it has contributed to an understanding of the flora visited by brown lacewings on the NAP, and minimum distances traversed by adults as they move between these plant species. Future research on lacewing movement would contribute to the development of the potential of brown lacewings into an Integrated Pest Management system on the NAP.

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7. Information Days and Surveys held at the Greenhouse Demonstration Site of Virginia

Introduction The dissemination of information during a scientific research program is very important, often under resourced, and seldom evaluated. The ‘revegetation by design’ project based on the northern Adelaide Plains presented significant challenges to information exchange, due to a lack of background knowledge of native plant species, limited understanding of the principles of integrated pest management, and the diverse cultural backgrounds of the horticultural growers. The approach to disseminating information was purposeful, and included information days and tours. Scientific results were delivered at these sessions via speeches and large displays consisting of live insects and plant specimens, viewing microscopes, poster graphs and images. Related project work was highlighted and cultural methods for establishing native plants were described. Each information day incorporated a tour of the main research plot of the project at the Greenhouse site. This site and two others of the project have large metal signs erected that acknowledge the project partners and describe the project. Bill Doyle - the main revegetation consultant to the project, who has assisted with site establishment and ongoing maintenance and advice, conducted the site tours. However, another component of the information days has been a paper survey. The surveys were conducted over three years to provide an evaluation of this approach. The aim was to assess any changes in community perceptions, and behaviour toward native plants and pest management over the course of the project. Materials and Methods Three formal project specific information days and tours have been held since the start of the project. All were conducted at the Greenhouse Demonstration Site managed by the Virginia Horticulture Centre, in conjunction with other horticulture project activities in the area, such as the Clean up the Adelaide Plains Strategy. Information Days Promotion Promotion of the information days was usually via a mailed-out colour flyer to the large database of the Virginia Horticulture Centre as an insert into their newsletter. The Centre staff has also promoted the events during their grower visits and meetings, as have SARDI staff. Phone calls direct to growers and consultants after the reply dates, have assisted to increase attendance numbers. Further distribution of the flyer to promote the information days was via dropping off bundles of flyers at the following Virginia locations:

• Elders Stores Virginia and Pooraka • PnP Vietnamese Grower supply store Virginia • Virginia Irrigation • Biological Supplies • Stardrip Irrigation

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• Stoeff Greenhouse Supplies • EE Muirs Store • Woodstock Nursery • Virginia Horticulture Centre • Di Mannos Grower Supply Store.

Information Days Format The days have always had four or more speakers arranged including Glenys Wood the Research Officer. Each time the Project Leader has had an introductory speaking role, and other speakers have covered their own subject areas that often bore a relationship to the project. The agenda for the days was typically as follows:

• Welcome introduction • Formal speeches and presentations, survey introduced • Filling of survey forms, viewing of displays, networking and question time • Food and drink service • Hosted tour of the research plot • Return to food and drink area for more networking and information exchange.

The program as outlined above was usually of three hours duration. The project displays consisted of native plant specimens in large tubs, live pest and natural enemy samples in Petri dishes for viewing under 3 microscopes, A4 photograph images of pests and natural enemies, A3 size hanging poster graphs of research results with both English and Vietnamese text explanations and a table for project evaluation. Project Evaluation The format of project evaluation consisted of a paper survey at three intervals, conducted at each of the Information days. Broadly, the aim of the paper survey is to assess community perceptions with regard to native vegetation and gauge what they may have perceived from the content delivered at the information days. Each evaluation was done via the same anonymous paper survey consisting of 6 questions in both English and Vietnamese. In order to answer all the questions, participants referred to a photo board with eight large numbered colour photo images of both weeds and native plants. A copy of the survey form is included at the end of this section. The surveys were all conducted prior to the site research tour component of the information days. All participants were encouraged to fill in survey forms. A few did this voluntarily without being asked in the course of their visit. Completed forms were returned to a marked box at leisure. Survey Results Information Day 1, April 2004 This information day was held in conjunction with an Open Day organized by the Virginia Horticulture Centre. Approximately 500 people visited the site during the day and 38 of those filled in survey forms. The large audience was randomly asked to participate as the opportunity arose. A summary of the key findings is described below:

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• 10 participants filled in the Vietnamese form, 28 the English version. • All the Vietnamese respondents were either growers or ex growers doing consulting. • 15 respondents overall were growers, and the remainder were ‘others’, volunteer planters,

consultants, council staff, and agribusiness staff persons in that order. • 28 believe native vegetation is better adapted to our environment. • 33 believe more needs to be done to encourage natural control of pests and diseases. • 32 believe weeds can harbour insect pests and diseases. • 29 believe natives improve the image of a farming area. • 26 believe natives are capable of lowering the water table and delaying soil salinity. • A large majority of respondents identified which plants in the photos were natives although

few could name them. • 30 think we should plant more natives. • 13 respondents have native vegetation on their properties that they look after. • The Vietnamese growers showed appreciation of native plants but were more likely to say that

we should clear it for farming. Information Day 2, October 2005 Despite extremely blustery and muddy conditions, approximately 30 people visited the site on the day and 23 of those filled in survey forms. As with the last survey, the results show that there is a good appreciation of the value of native vegetation in the community. They are able to identify native plants on-sight, and have the opinion that we should plant more. A summary of the October survey is described below:

• Three participants filled in the Vietnamese form, 20 the English version. • Seven respondents overall were growers, eight were agribusiness staff, six consultants, one

council staff, and one student. • 18 believe we should plant more native vegetation. • Question 2 of the survey is a true or false exercise. There are 10 attributes of native

vegetation listed in question 2 that are true. 18 respondents stated they believed 8 or more of them. This shows a large increase in understanding of the attributes of native plants compared to the last survey 18 months prior.

• Nine respondents were able to identify correctly all the plants that were native in the photo images. Seven were 80% accurate and the remainder got 60% or less correct. None failed to pick at least one native plant correctly from the images. These results show a higher level of knowledge than was reflected in the last survey.

• A noticeable difference in this survey was that the comments of the Vietnamese growers showed greater appreciation of native plants.

Information Day 3, March 31 2006 This third smaller information workshop, tour and survey was conducted on March 31st 2006 as part of the DOTARS ‘Revegetation by Design’ commitment which continues until November 30 2006. Approximately 25 people attended the day and eight of those filled in survey forms. A summary of this survey follows:

• Two participants filled in the Vietnamese form, six the English version. • Four respondents overall were growers, three were agribusiness staff, one natural resources

staff of a local Board. • 40% believe we should plant more native vegetation. • In Question 2 of the survey’s true or false exercise, six respondents got 80% or more correct.

This shows a slight decrease (3%) on the results last survey. • One respondent was able to identify correctly all the plants that were native in the photo

images. All got more than half correct.

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Accumulated Result In the graph that follows, the final column showing those respondents that achieved ‘50% or more accuracy in ID of native plants’ refers only to the identifying of whether the plant was native or not. It does not refer to the ability of the respondent to identify a native plant by its specific or common name. Figure 7.1. Combined survey results of selected categories from the questionnaire Discussion The forum for the evaluations was open to all interested attendees without discrimination. The same people are not necessarily represented across the three assessment days. Therefore, any comparison of the increase in awareness and appreciation of the benefits of native vegetation must be qualified because the respondents are not consistent over the three survey periods. However, the Vietnamese growers are mostly the same people and greater inferences can be drawn regarding this specific group. Being an anonymous survey there is no attempt to match the responses in any way. In the last two surveys, the numbers of respondents is lower than the first survey. However, the respondents are a more concentrated mix of locals, so the results do reflect what exists in the regional community. Regardless of the limitations listed above, there does seem to be a progressive increase in understanding and appreciation of native vegetation over time. The use of several information days progressively through the project has been useful in introducing and reinforcing basic concepts. The

COMBINED SURVEY RESULTS

0

10

20

30

40

50

60

70

80

RespondentsOverall

GrowersVietnamese

Growers English 80% or More ofAttributes of NV

Known

Say to PlantMore Natives

50% or MoreAccuracy in ID of

Natives

Res

pond

ent N

umbe

rs

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increased awareness resulting from the release of information in stages should give the final recommendations greater impact and wider acceptance. Generally, the information days were important in increasing community awareness of the concept of ‘revegetation by design’. However, the use of grower’s properties for trial sites, linkages with local councils and associated campaigns (Clean up the Adelaide Plains), and frequent interaction of the project staff with growers, was also very important in creating a positive environment for information exchange. Questionnaire The survey questionnaire is copied below without the original formatting:

1. Please tick which you are -

A grower A consultant Agribusiness staff person A council staff employee A volunteer planter Other……………………………

2. Tick any of the following statements that you believe to be true -

Native vegetation is more adapted to our environment than other plants. Native and horticultural plants grown side by side can be compatible. Some seeds and fruit of native vegetation can be eaten by humans. On the Northern Adelaide Plains we have more native plants than other plants. Native plants are harder to care for than non-native. Horticultural insect pests and diseases can come from native vegetation. Native plants are capable of lowering the underground water table and delaying

salinity of soil. More needs to be done to encourage natural control of pests and diseases. Established native plants are good competition for weeds. Natural enemies of pests can be native and live on native vegetation. Weeds can harbour insect pests and diseases. Native plants improve the image of a farming area.

3. Please look at the photo board. Do you know which of the plants pictured are native? Tick the matching number below. Write the name of the plant beside if you know it.

1………………………………… 2………………………………… 3………………………………… 4………………………………… 5………………………………… 6………………………………… 7………………………………… 8…………………………………

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4. How do you regard native vegetation? Tick any of the following that you agree with. I currently have native vegetation on my property and look after it We should plant more of it We should look after what we have but not create more We should clear it all for farming or other plants

5. Write the reason for your answers at Question 4.

Any other comments or suggestions for the ‘Revegetation by Design Project’?

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8. Implications and Recommendations Native plant plots established near horticulture have allowed us to gather information about the diversity and abundance of pest and beneficial arthropods present on native plants on the NAP. The results suggest that the native plants and grasses selected have very low Western Flower Thrips numbers compared with common brassica weeds. Virus screening of selected native plants suggests that they do not host Tomato Spotted Wilt Virus (TSWV). In addition, we have obtained practical knowledge on the successful establishment techniques and agronomic suitability of a number of these native plants and grasses to the Northern Adelaide Plains (NAP). Considerable knowledge and insights have been gained, but to make improved and reliable recommendations further investigations are required:

1. Further work should include the evaluation of currently selected native species over several seasons, and in larger stands to ensure that potential new pests or plant host shifts of existing pests are detected early.

2. Further evaluation of additional native species is required for specialist applications, such as

road verges and water/hydroponic waste ditches.

3. The saltbushes, in particular, A. semibaccata, harbour large numbers of leafhoppers. It may be possible to manage the threat by growing A. semibaccata in a mixed sward, but there is a need to compare the invertebrate composition of pure and mixed swards.

4. There is considerable concern regarding the introduction of lettuce aphid and potential spread

into South Australia. Native grasses require host specificity testing for a range of pest aphids, including lettuce aphid.

5. The beneficial suite of invertebrates on native plants and grasses requires further investigation.

In particular, parasitic wasps associated control of thrips, predatory Erythraed mites found on native grasses, and brown lacewings for potential in IPM strategies to control lettuce aphid.

6. Interesting areas for further study include, the diversity of coccinellid species on the native

grasses and Rhagodia parabolica, and Chirothrips manicatus as a host for parasitic wasps associated with the control of pest thrips, or generalist predators, during breaks in the cropping cycle.

Overall, the next step is to design and establish native vegetation plantings at the property level. The design will involve several elements including, native species selection, mixed swards and direct seed mixes, and consideration of neighbouring plants (native and exotic), Greenhouse design, machinery access, saline areas, water/hydroponic waste ditches, field crops plantings and the adjacent road verge.

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9. References Black, JM 1986, Flora of South Australia JP Jessop & Hr Toelken (eds), State Herbarium South

Australia (4th edn), pp. 236, South Australian Printing Division, Adelaide. Bonney, N 2003, What seed is that? Field guide to the identification, collection and germination of

native seed in South Australia. Revised Edition, Beverly South Australia. Del Socorro, AP & Gregg, PC 2001, ‘Sunflower (Helianthus annuus L.) pollen as a marker for studies

of local movement in Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae)’. Australian Journal of Entomology, vol. 40, pp. 257-263.

Duelli, P & Obrist, MK 2003, ‘Regional biodiversity in an agricultural landscape: the contribution of

seminatural habitat islands.’ Basic and Applied Ecology, vol. 4, pp. 129-138. Faegri, K, Kaland, PE & Krzywinski, K 1989, Textbook of pollen analysis. (4th edn) John Wiley and

Sons, Chichester. Gray, KW & Schuh, J 1941, ‘A method and contrivance for sampling pea aphid populations.’ Journal

of Econonomic Entomology, vol. 34, pp. 411-15. Gregg, PC 1993, ‘Pollen as a marker for migration of Helicoverpa armigera and H. punctigera

(Lepidoptera: Noctuidae) from western Queensland’, Australian Journal of Ecology, vol. 18, pp. 209-219.

Gurr, GM, Wratten, SD & Luna, JM 2003, ‘Multi-function agricultural biodiversity: pets management

and other benefits’, Basic and Applied Ecology vol. 4, pp. 107-116. Hele, A 2001, ‘The Native Food Industry in SA’. Primary Industries and Resources SA Fact Sheet

[online: www.pir.sa.sa.gov.au/factsheets]. Horne, PA, New, TR & Papacek, D 2001, ‘Micromus tasmaniae: a key predator on aphids on field

crops on Australasia?’ in P McEwen, T New, & A Whittington (eds), Lacewings in the Crop Environment, pp. 388-392, Cambridge University Press.

Horsman, CH & Delaporte, K 2002, ‘Eucalypts for floriculture: A growers guide’, (RIRDC

Publication No. 02/132). Kearns, CA & Inouye, DW (1993) Techniques for pollination biologists, University Press of

Colorado, Colorado, USA. Kraehenbuhl, DN 1996, Pre-European vegetation of Adelaide: A survey from the Gawler River to

Hallet Cove, Nature Conservation Society of South Australia Inc. Adelaide. Lamp, C & Collet, F 2002, Field Guide to Weeds in Australia, Inkata Press Melbourne-Sydney. Lanza, B, Marsilio, V & Martinelli, N 1996, ‘Olive pollen ultrastructure: characterization of exine

pattern through image analysis-scanning electron microscopy (IM-SEM)’, Scientia Horticulturae, vol.65, pp. 283-294.

Latham, LJ & Jones, RA 1997, ‘Occurrence of tomato spotted wilt virus in native flora, weeds, and

horticultural crops’, Australian Journal of Agricultural Research, vol. 48, pp. 359-369.

77

Lewis, T (ed.) 1997, Thrips as crop pests, p. 447, CAB International, Wallingford. Moerkerk, MR & Barnett, AG 1998, More crop weeds, Department of Natural Resources and

Environment. Moore, PD, Webb, JA & Collinson, ME 1991, Pollen analysis, (2nd edn), Blackwell Scientific

Publications, Oxford UK. Murray, R 1994, Seed collection of Australian native plants, (2nd edn) Fitzroy, Victoria. Oliver, I & Beattie, A 1996, ‘Invertebrate morphospecies as surrogates for species: a case study’,

Conservation Biology, vol. 10, pp. 99-109. SAS Institute 2001, ‘SAS/STAT User’s manual version 8.2 SAS Institute’, Cary, NC. Schellhorn, NA & Silberbauer, X 2002, ‘The role of crops and surrounding vegetation: Increasing the

effectiveness of predators and parasitoids in cotton and broccoli systems’, First International Symposium on the Biological Control of Arthropods, Honolulu, Hawaii, USA.

Sedgley, M, Sierp, M, Wallwork, MA, Fuss, AM & Thiele, K 1993, ‘Pollen presenter and pollen

morphology of Banksia L.f. (Proteaceae)’, Australian Journal of Botany vol. 41, pp. 439-464. Silberbauer, L, Yee, M, Del Socorro, A, Wratten, S & Gregg, P 2004, ‘Pollen grains as markers to the

track movements of generalist predatory insects in agroecosystems.’, International Journal of Pest Management, vol. 50(3), pp. 165-171.

Silberbauer, LX 2001, ‘Sources of beneficial insects colonising cotton fields’, Final Report Australian

Cotton Cooperative Research Centre. Silberbauer, LX & Gregg, PC 2003, ‘Tracing short-term beneficial insect movement using insect-

borne pollen.’ in Proceedings of the First International Society for the Biological Control of Arthropods meeting, Honolulu, Hawaii, USA: USDA Forest Service pp. 501-505.

Slater, AT 1999 ‘Broombush baeckea wildflowers - commercial prospects’, RIRDC Short Report No

71 [online; www.rirdc.gov.au/pub/shortreps/sr71.html] Stephens, CJ, Schellhorn, NA, Wood, GM & Austin, AD 2006, ‘Parasitic wasp assemblages

associated with native and weedy plant species in an agricultural landscape’, Australian Journal of Entomology, vol. 45, pp. 176-184.

Wilding, JL, Barnett, AG & Amor, RL 1998, ‘Crop weeds’, Inkata Press Melbourne. Yee, M 1998, ‘Identifying potential habitats of predators of Helicoverpa spp. in two cotton growing

regions.’, Unpublished B.Sc. Honours Thesis. Armidale, NSW 2351, Australia: School of Rural Science and Natural Resources, University of New England, Australia.

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10. Appendices

79

Appendix 1. Plates 1 - 6 PLATE 1 – CHENOPODIACEAE

Scale = 10μm Image no.

Family Scientific name and Author (s)

Length um Mean ± SE (n)

Width um Mean ± SE (n)

Diameter um Mean ± SE (n)

Shape

1 Chenopodiaceae Atriplex padulosa (R.Br.) - - 22.6±0.5 (5) S 2 Chenopodiaceae Atriplex padulosa (R.Br.) - - 22.6±0.5 (5) S 3 Chenopodiaceae Atriplex cinerea Poir. - - 20.1±0.5 (22) S 4 Chenopodiaceae Atriplex cinerea Poir. - - 20.1±0.5 (22) S 5 Chenopodiaceae Atriplex semibaccata (R.Br.) - - 19.6±1.1 (5) S 6 Chenopodiaceae Atriplex suberecta (I. Verd) - - 15.8±0.3 (8) S Shape Key: S=Sphere; O= Ovoid; T=Triangular

2 1

4 3

6 5

80

PLATE 2 – CHENOPODIACEAE

Scale = 10μm Image No.





Shape

7 Chenopodiaceae Rhagodia crassifolia (R.Br.) - - 19±0.2 (26) S 8 Chenopodiaceae Rhagodia crassifolia (R.Br.) - - 19±0.2 (26) S 9 Chenopodiaceae Rhagodia candolleana (Moq) - - 18.2±0.3 (21) S 10 Chenopodiaceae Rhagodia candolleana (Moq) - - 18.2±0.3 (21) S 11 Chenopodiaceae Rhagodia parabolica (R.Br.) - - 15.9±0.3 (9) S 12 Chenopodiaceae Chenopodium album L. - - 20±0.6 (3) S Shape Key: S=Sphere; O= Ovoid; T=Triangular

7

10 9

12 11

8

81

PLATE 3 – MIMOSACEAE AND MYRTACEAE

Scale = 10μm Image No.

Family Scientific name and Author (s) Length um Mean ± SE (n)



Shape

13 Mimosaceae Acacia baileyana F. Meull - - 49.4±0.7 (4) O 14 Mimosaceae Acacia victoriae Benth. - - 46±1 (7) O 15 Myrtaceae Baeckea behri (Schldl) F. Meull 10.3±0.2 (7) - - T 16 Myrtaceae Melaleuca lanceolata Otto 12±0.6 (7) - - T 17 Myrtaceae Eucalyptus gillii Maiden 22.5±0.3 (10) - - T 18 Myrtaceae Eucalyptus tetragona (R.Br.) F.Muell. 12.7±0.2 (3) - - T Shape Key: S=Sphere; O= Ovoid; T=Triangular

13

16

17

14

15

18

82

PLATE 4 – POACEAE AND GOODENIACEAE






Shape

19 Poaceae Chloris truncata R.Br - - 23.9±0.3 (22) S 20 Poaceae Danthonia linkii Kunth - - 35±2.6 (6) S 21 Poaceae Enneapogan nigricans (R.Br.) - - 31.1±0.9 (8) S 22 Poaceae Themeda triandra Forssk. - - 46.5±0.8 (22) S 23 Goodeniaceae Goodenia ovata Sm. 34.9±1.5 (6) 20.3±4.7 (2) - O 24 Goodeniaceae Goodenia ovata Sm. 34.9±1.5 (6) 20.3±4.7 (2) - O Shape Key: S=Sphere; O= Ovoid; T=Triangular

19

22 21

24 23

20

83

PLATE 5 – MYOPORACEAE, BRASSICACEAE, OXALIDACEAE, BORAGINACEAE AND SOLANACEAE






Shape

25 Myoporaceae Myoporum parvifolium R.Br 26.5±0.8 (18) 15.6±0.2 (21) - O 26 Brassicaceae Rapistrum rugosum (L.) All. 30±2.6 (2) 16.3±1.1 (2) - O 27 Brassicaceae Raphanus raphanistrum L. 31±0.3 (15) 17.8±0.2 (15) - O 28 Oxalidaceae Oxalis pes caprae L. 58.5 (1) 34 (1) - O 29 Boraginaceae Echiium plantagenum L. 21.9±0.5 (3) 12.2±0.3 (4) - O 30 Solanaceae Solanum elaegnifolium Cav. 35.6±0.2 (4) 23.1±0.4 (4) - O Shape Key: S=Sphere; O= Ovoid; T=Triangular

28 27

30 29

26 25

84

PLATE 6 – UMBELLIFERAE, AZIOACEAE, MALVACEAE AND ASTERACEAE






Shape

31 Umbelliferae Foeniculum vulgare Mill. 28.4±0.5 (10) 11.3±0.1 (10) - O 32 Azioaceae Galenia pubescens (Eckl.&Zeyh) Druce 27.1 (1) 15.8 (1) - O 33 Malvaceae Malva sp 21.7±0.7 (26) - - O 34 Asteraceae Sonchus oleraceus L. - - 34.4±0.8 (11) semi O 35 Asteraceae Lactuca serriola L. - 29.2±0.6 - semi O 36 Asteraceae Lactuca serriola L. - 29.2±0.6 - semi O Shape Key: S=Sphere; O= Ovoid; T=Triangular

34 33

36 35

32 31

85

Appendix 2. Information Transfer Scientific publications Stephens CJ, Schellhorn NA, Wood GM, Austin A D (2006) Parasitic wasp assemblages associated

with native and weedy plant species in an agricultural landscape. Australian Journal of Entomology 45, 176-184

Conference Papers and Posters Wood GM, NA Schellhorn (2004) Weeds and native vegetation as hosts for pest and beneficial thrips

(Thysanoptera) in a South Australian horticultural landscape. XXII International Congress of Entomology’, Brisbane, Queensland, Poster presentation, August.

Wood GM (2005) Brown lacewings could eat your aphids ‘3rd. Australian Lettuce Industry

Conference’, Werribee, Victoria. Poster presentation, May. Doyle B (2005) Constructed sites for amenity – Invited presentation for ‘The Management of Native

Grasses in the Urban Landscape” Michael Hyde Memorial Native Grass Forum’, Urrbrae, South Australia. Data on the abundance and species richness of beneficial insects was presented as part of the Revegetation by Design project as part of the urban landscape within the City of Playford, SA. Oral paper, August.

Wood G, Doyle B, Marshal A (2005) When Less is More – Designing Biodiversity ‘National

Conference of the Australian Network for Plant Conservation The Challenges Of Change’, Poster presentation, September

Wood GM, Schellhorn NA, Taverner PD (2005) Revegetation by Design – Horticulture meets natural

resources management on the Northern Adelaide Plain. ‘South Australia Australian Entomological Society 36th AGM and Scientific Conference 7th Invertebrate Biodiversity and Conservation Conference Society of Australian Systematic Biologists Conference, Theme “Use It Or Loose It: Invertebrate Diversity In Landscape Management”’ Canberra. Oral paper, December.

Wood G, Doyle B (2006) Designing the “right” biodiversity for conservation and horticultural

production Workshop presentation ‘Veg Futures: The conference in the field. The role of vegetation in productive landscapes: from regional planning to practice’, Albury-Wodonga. Oral paper, March

Information Days Information Session November 2003. VHC Greenhouse Modernisation Project, ‘Revegetation by Design’ trial site,

• Australian Government’s Sustainable Regions Programme Award announcement with $511.383.00 presented by Mrs Trish Draper

• Attended by state and federal ministers and included growers and different groups from the community.

• Scientific information delivered and tour of main research plot. Information Session April 2004. VHC Greenhouse Modernisation Project, ‘Revegetation by Design’ trial site,

• Attended by growers, growers, horticultural and NRM consultants and local council staff involved in revegetation in a production and/or natural resources management context.

• Scientific results presented and tour of main research plot conducted.

86

Information session/Tour May 2004. VHC Greenhouse Modernisation Project, ‘Revegetation by Design’ trial site,

• Attended by PIRSA Regional Executive key horticulture industry representatives. • Overview of the project including new results and followed by site tour

Information Session October 2004. VHC Greenhouse Modernisation Project, ‘Revegetation by Design’ trial site,

• Approximately 300 attendees • Data on the presence of key insect pest vectors on a selected range of weeds and native plants

were presented. • The benefits and constraints of establishing individual native plant and grass species were

highlighted • Questions answered during the tour of the demonstration plot.

Information Session October 2005. VHC Greenhouse Modernisation Project, ‘Revegetation by Design’ trial site,

• held in conjunction with the Cleanup the Adelaide Plains Strategy • Attended by growers, growers, horticultural and NRM consultants and local council staff

involved in revegetation in a production and/or natural resources management context. • Scientific results presented and tour of main research plot conducted.

Scientific Forum February 2005 Waite Campus of University of Adelaide,

• Dr Nancy Schellhorn (CSIRO Entomology, Brisbane) visited to collaborate with scientists involved with the project.

• Dr Peter Taverner presented current results followed by discussion surrounding the important pest and beneficial insect complexes highlighted from the native plant survey.

• Sampling techniques, virus detection techniques and the results of pollen studies were discussed.

• Future research directions, collaborations and proposals were also discussed. Presentations Southern Vales Bush Foods Inc - March 2004, Native plants in Integrated Pest Management Clean up the Adelaide Plains Task Group - September 2004, Where are the Western Flower Thrips?

City Of Playford - September 2004,‘Weeds and native vegetation as hosts for pest and beneficial

thrips (Thysanoptera) in a South Australian horticultural landscape’ Playford Civic Centre - December 2004, The Revegetation by Design Project was presented at ‘‘The

Sustainable Region’ Celebratory event’ for Playford /Salisbury Sustainable Regions Program. VHC Greenhouse Modernisation Project - March 2004, Cultural methods and pest management

implications for growing bush foods on the Northern Adelaide Plains. VHC Greenhouse Modernisation Project - December 2004, Cultural and pest management aspects of

using native re-vegetation in an agricultural landscape to a delegation from Shandong Province, China

Virginia Horticulture Centre - March 2005, to South Australian Lettuce Growers Group –

Revegetation with native plants on road verges, potential benefits to lettuce crops.

87

Media Press Release - February 2003 –Native Revegetation May Send Plains Pests Packing. Thousands of

insect pests living on Adelaide’s northern plains may eventually be sent packing as a result of research by the South Australian Research and Development Institute (SARDI).

Radio Interview, 5CK (Port Pirie) - February 2003 Compere: Leigh Radford – “SARDI is looking at

how native vegetation can be used to encourage beneficial insects and battle pests” Popular Articles The GROWER - March 2003, Native revegetation sends pests packing. PIRSA OpenGate - December 2003, Revegetation options boosted by $500,000 News Review - December 2003, Plants to control weeds, pests Virginia Horticulture Centre Newsletter - April 2004, Revegetation by Design project. Jeffries Buckland Park Update - May 2004, Discussions with other groups working in the area. Jeffries Buckland Park Update - October 2004, Research shows early mulching benefits native plants. The GROWER - April 2005, Weed problems slashed. PIRSA OpenGate - June 2005 – Two articles showcasing the project. Native insects may feast on pest

aphids, and Cleaning up the Adelaide Plains Good Fruit And Vegetables - November 2005, Natural pest control links native vegetation with

horticulture. Signage and Web site Two signs explaining the “Re-vegetation by Design – A partnership project” have been installed (one at the GMP and the other to highlight a demonstration plot on a grower property at Virginia). In addition we have installed project information on the SARDI website in July 2004. The information has been monitored and updated and will remain on the website. The website covers who is involved, why the project exists, the project benefits, the research and recent findings. http://www.sardi.sa.gov.au/pages/ento/hort_pests/reveg.htm:sectID=469&tempID=1

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