Identification, Biology, & Control of Aboveground Pests in FL CitrusJanuary 23, 2019

• What is IPM?

• What kind of information do you need to develop an IPM program?

Managing pests effectively requires knowledge of their population, phenology, and host association(s)

Citrus Production in FL

• Perennial crop

• Historically stable ecosystem regarding insect management• Low insecticide inputs prior to ACP

• Retention of beneficial species (e.g. lady beetles) within/near crops

• More cases of successful biological control than any other cropping system

• ACP + higher insecticide inputs:• T.B.D.

Introduction of invasive citrus pests

1964- Diaprepes root weevil

1995- Brown citrus aphid

L. Buss UF/IFAS

1993- Citrus Leafminer (CLM)

1998- Asian citrus psyllid (ACP)

Arthropod Pests Affecting Florida Citrus Production

• Introduced into California in 1888

• First outstanding success in the field of classical biological control

• Successfully repeated in Florida in 1899

Vedalia lady beetle (Rodolia cardinalis)

Cottony cushion scale (Icerya purchasi)

Arthropod aboveground impacts on citrus

• Fruit damage• Cosmetic vs destructive damage

• Foliage damage• Reduces photosynthetic capacity

• Reduces new growth

• Disease vectors• Insects that move diseases between hosts

Fruit DamageDirect damage to fruit

• Feeding reduces fruit quality, shape, or size

• Reduction in yield or cause fruit to drop

• Problem for fruit grown for fresh & processed markets

Damage to peel

• Largely cosmetic

• Problem for fresh market

Damage from leaf-footed bug feeding.

Weeks UF/IFAS CREC

Thrips feeding damage on peel.

UF/IFAS CREC

Stinkbugs and Leaf-footed bugs

Use piercing-sucking mouthpart topuncture fruit & feed. Feeding holes create openings for secondary pests/pathogens to enter including bacteria, fungi, and other insects.

Weeks UF/IFAS CREC Weeks UF/IFAS CRECWeeks UF/IFAS CREC Weeks UF/IFAS CREC

Weeks UF/IFAS CREC

Rust mitesPredominant arthropod pest of fresh & processed

citrus in Florida

Citrus rust mite

(Phyllocoptruta oleivora)

Pink citrus rust mite

(Aculops pelekassi)

UF/IFAS CREC UF/IFAS CREC

• Damage• Feeding injury • Russeting of fruit & leaves• Mild to severe distortion of new leaf

growth• Brown lesions on lower surfaces &

along midribs of mature leaves• May produce mesophyll collapse,

chlorosis, and leaf drop

Rust mite damage to citrus

Leaf distortion on new growth

Citrus rust mitePhyllocoptruta oleivora (Ashmead)

UF/IFAS CRECUF/IFAS CREC

Rust mite development

• Females lay 2 eggs/day

• ~30 eggs in a lifetime

• Egg adult in 6 days

• Adult male longevity approx. 6 days

• Adult female longevity approx. 14 days

Citrus rust mite seasonalityPhyllocoptruta oleivora (Ashmead)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0

UF/IFAS CREC

CRM populations peak in early summer, then again at a smaller scale in mid-late fall depending on weather.

Pink citrus rust miteAculops pelekassi (Keifer)

UF/IFAS CREC UF/IFAS CREC

PCRM damage to fruit appears as bronzing all over because it is done early in the fruit’s development.

Pink citrus rust mite (PCRM)Aculops pelekassi (Keifer)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0

PCRM populations peak in mid spring/early summer.Populations build up on flowers & leaves prior to feeding on fruit.

UF/IFAS CREC

Early in the season, pink citrus rust mites are more prone to damage leaves than the citrus rust mite

Natural enemy complex for rust mites

Phytoseiid image: http://keys.lucidcentral.org/keys/v3/phytoseiidae/key/phytoseiidae/Media/Html/mites.htmTydeid image: https://de.wikipedia.org/wiki/Datei:Yellow_mite_(Tydeidae),_Lorryia_formosa.jpg

Citrus rust mites

Stigmaeidae

A. Pelegrin

Cheyletidae

E. McDonald

Phytoseiidae

Tydeidae

Disease(next slide)

Other predacious arthropods:lady beetles, ants, spiders,

lacewing larvae….

Hirsutella thompsoniiFungal pathogen of mites, biological control for rust mites in citrus

Control of CRM by

Hirsutella

Action thresholds for control of rust mites

• Processed fruit• 10 rust mites / 2 cm2

• Controlled with 1-3 oil or miticide applications/season

• Fresh fruit• 2 rust mites / 2 cm2

• Controlled with 3-5 miticide applications/season

Citrus mealybugPlanococcus citri• Most commonly found in spring and early summer

• Prefer sheltered locations

• Females lay 300-600 eggs

• Damage

• Feeding causes cosmetic damage to fruit

• Produce large amounts of honeydew, leads to problems with sooty mold

• Can cause heavy fruit drop in grapefruit

• Cultivars most affected: grapefruit, navals, valencia

Natural enemies of citrus mealybug

• Mealybugs generally occur at low levels and are kept in check by three natural enemies:

• Cryptolaemus montrouzieri

• Lady beetle

• The “mealybug destroyer”

• Found in groves May-June

• Entomophthora fumosa

• Fungus

• Prevalent after summer rainy season starts

• Leptomastidae abnormis

• Hymenopteran parasitoid

Various species of lady beetles (Coccinellidae) contribute to the mortality of several citrus pests.

Cryptolaemus montrouzieri- “mealybug destroyer”- Efficient predator of mealybugs despite

the waxy covering- Nymphal stages LOOK like mealybugs- Can be purchased for release, but there

are drawbacks…

Nymph Adult

Control of Mealybugs

• Effective products for mealybugs have negative impacts on beneficial insect populations

• Insecticides should ONLY be applied to severe infestations

• Applications are most effective when applied before mealybugs have settled between fruit clusters

• Fruit clusters serve as shelter from

management actions BUT naturally

occurring predators can often reach

these locations

Scale insect pests of citrus• Several species of ARMORED SCALES can be problematic

• Red scale, purple scale, Chaff scale

• Scale insects in Florida have historically been under biological control by a large number of natural enemies

• Not currently considered key pests in the development of pest management programs

D. Papacek http://thecitrusguy.blogspot.com/2012/05/citrus-with-some-mussel.html

“Secrets to success” for biological control of scale insects• Adult scales are sessile- either VERY slow moving or not moving at

all

• High number of offspring to support natural enemy population growth

• Populations tend to be concentrated easy for natural enemies to find

Aggregation of red scale on green fruit

Florida red scaleChrysomphalus aonidum• Damage

• Feeding occurs on leaves, green twigs, and fruit

• Feeding causes discoloration at the feeding siteUF/IFAS CREC

UF/IFAS CREC UF/IFAS CREC

Florida Red Scale (Chrysomphalus aonidum)

• Red scale now under biological control by parasitic wasps released in Florida (Aphytis wasps)

• Good example of successful classical biological control

Florida red scale• Left: FRS Adult Female with Cover Lifted

• Lower left: 3rd instars of Aphytis holoxanthuson adult female scale

• Below: 5 fresh pupae of Aphytis holoxanthusunder FRS cover

Purple scaleLepidosaphes beckii

• Once major pest of fruit, leaves, and twigs

• Populations are highest in late spring/early summer

• Parasitoid (Aphytis lepidosaphes) introduced in 1950s to manage

UF/IFAS CREC

Parasitoid emergence hole

UF/IFAS CREC

Chaff scaleParlatoria pergandii• Often found on trunk and inner canopy

• Fruit feeding causes spotting

• Slow rate of reproduction + parasitoid Aphytis hispanicus historically kept populations low

UF/IFAS CREC

UF/IFAS CREC

Thrips• Flower thrips

• Frankliniella bispinosa

• Frankliniella kelliae

• Orchid thrips

• Chaetanaphothrips orchidii

• Danothrips trifasciatus

• Greenhouse thrips

• Heliothrips haemorrhoidalis

• Chili thrips

• Scirtothrips dorsalis

L. Buss UF/IFAS UF/IFAS CREC

Thrips move between plants, making them a huge challenge to manage.

Thrips populations can reach high numbers in flowers (semi-protected)& lead to fruit damage

F. bispinosa collected from 20 open flowers/rep in March 2001 (Hillsborough Co.)

Variety Adults Larvae

Murcott 604 203

Murcott 815 379

Murcott 602 611

Rhode Red Valencia 2,166 1,696

Rhode Red Valencia 2,749 1,488

Rhode Red Valencia 2,468 855

Rhode Red Valencia 2,061 1,070

Control of F. bispinosa on ‘Navel’

Treatment Insecticides RateApplication

dateMean no. fruit/m3

% yield increase

1

Chlorpyrifos 4EC 7.01 L 14 Feb

34.2a 43Formetanate

hydrochloride 92 SP1.4 kg 1 Mar

2

Dimethoate 4 EC 8.18 L 14 Feb

33.9a 42Formetanate

hydrochloride 92 SP1.4 kg 1 Mar

3Formetanate

hydrochloride 92 SP1.4 kg 15 Feb 27.9b 17

control n/a -- -- 23.9c --

Childers. 1992. J. Econ. Entomol. 85: 1330-1339

1921 The Citrus Industry 2(3): 19

J.R. Watson

1940 The Citrus Industry 21: 5, 8-9, 12-13, 17

“…the so-called thrips marks are

caused by the young fruit being

rubbed against leaves and

twigs…not by thrips.” (W.C. Thompson)

Does F. bispinosa cause scarring damage to ‘Murcott’ fruit?

Thrips caging study on ‘Murcott’ blooms

Outcome of caging study:

Caged study- 35 days after caging

No thrips 10 thrips 25 thrips

UF/IFAS CREC

Thrips feeding damage on ‘Murcott’

fruit

No Economic Injury Level set

UF/IFAS CREC UF/IFAS CREC

Orchid and Greenhouse Thrips

• Cause rind blemishes on developing fruit, in particular “ring spotting”

• Develop in protected areas (under calyx, between touching fruit)

• Primarily a problem on red grapefruit varieties but can occur on white grapefruit varieties as well

UF/IFAS CREC

UF/IFAS CREC

UF/IFAS CRECUF/IFAS CREC

Ring scarring where fruit in clusters were touching

Monitoring Orchid and Greenhouse thrips

• Examine interior clusters of red grapefruit when fruit are beginning to touch

• Use 10x hand lens to search for thrips (larvae and adults) on fruit where touching

• If most clusters sampled contain thrips, then insecticide application may be justified

•This damage is cosmetic in nature and does not affect internal fruit quality

Chili Thrips(Scirtothrips dorsalis)

• Recently introduced pest in Florida (2005)• Damage leaves and scar fruit

Host Plants:Over 150 host plants including banana, beans, chrysanthemum, citrus, corn, cotton, cocoa, eggplant, ficus, grape, grasses, holly, jasmine, kiwi, litchi, longan, mango, onion, peach, peanut, pepper, rose, soybean, strawberry, tea, tobacco, tomato, viburnum, etc.

Chili Thrips damage

Rose Ligustrum (Privet)Pittosporum

Indian Hawthorn Schefflera Strawberry

Scirtothrips spp. (Thysanoptera: Thripidae)

S. aurantii Faure - (South Africa)

S. dorsalis Hood – (Japan & Africa)

S. citri (Moulton) – (California & Arizona)

Scirtothrips citri(Moulton)

Foliage Pests

• Primarily concerned with protection of foliage on young trees

• On mature trees, a few pests are occasionally problematic (i.e., spider mites)

• Pest problems typically associated with new flush

Young Trees

Goal: Optimize tree growth and vigor to bring trees into production within 3-4 years after setting

Young tree pest problems

UF/IFAS CREC

Citrus leafminer (CLM)- Phyllocnistis citrella

CLM history in Florida

• First recorded in Homestead in Spring 1993

• By December it spread up to the Georgia border

Citrus LeafminerLifecycle

Egg2-10 days

4 larval instars5-22 days

Pupal stage6-22 days

CLM can also cause damage to green twigs and in rare cases cause mining on fruit surface

Seasonality of CLM in Florida

• overwinter as adults with no reproductive diapause

• very low populations exist throughout winter months on the low levels of new flush being produced

• with warmer weather, CLM produce more offspring more rapidly

• populations build up to noticeable levels when the summer flush occurs (usually May to June)

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Bearing citrus 2006

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Importance of CLM Damage

• Damage alone not significant on mature trees (New flush : Canopy)

• Damage on non-bearing trees can reduce tree growth

• Increased time to bring trees into production

Canker / CLM Relationship

• Canker incidence can be up to 50% higher in groves where CLM damage is abundant (Sohi and Sandhu, 1968)

Choice & Timing of Pesticide Applications

Non-bearing/young citrus

• soil-applied imidacloprid application is the best option for preventing CLM damage (current UF/IFAS recommendation)

• applications should be made 10-14 days prior to anticipated flush

• expect about 8 weeks of control

• soil-applied imidacloprid just prior to summer flush and again just prior to the fall flush should provide control of CLM during this peak time for CLM damage

• may also provide control of Asian citrus psyllid during these times as well

Choice & Timing of Pesticide ApplicationsBearing citrus• preventing damage on bearing trees for canker management much

more difficult

• must rely on foliar applications if control warranted

• there are no soil-applied systemic insecticides available for CLM control on large, bearing trees

• as a general rule, there have never been any soil-applied systemic organophosphate or carbamate insecticides shown to provide effective control of CLM damage

• this includes aldicarb (Temik)*, dimethoate, oxamyl (Vydate), metasystox(MSR)

*Temik no longer registered for use in citrus

Soil imidacloprid application: Sept. 4; Foliar applications: Sept. 18

Control of Damage by Citrus Leafminer

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Control of Damage by Citrus Leafminer

Foliar treatments applied May 19

Timing of application for leafminer control

13 days from general budbreak is earliest time for application

Last potential date for leafminer application is 31 days after budbreak

[FOLIAR APPLICATIONS]

Effects of cultural practices on CLM populations

• Promoting winter flush may result in higher CLM populations earlier in the season

• hedging and topping

• excessive irrigation

• fertilization regimes

Biological Control of Citrus LeafminerAgeniaspis citricola: Imported into Florida from Australia in 1994

BEFORE intense ACP management, parasitism rates up to 86%were observed late in the season.

NOW-?

Use of Pheromones in Leafminer Management

Non-pesticide approaches to CLM control–Previous lecture by L. Stelinski

http://cisr.ucr.edu/images/citrus_laef_miner_1.jpg

Aphids

Aphids

• Depend on newly expanding leaves for their development

• Leaf curling

• Large amounts of honeydew (blocks photosynthesis)

• Treatment warranted on young trees when > 50% of new foliage is infested

Brown Citrus Aphid (BCA)

Toxoptera citricida

Vector of citrus tristeza virus

*CTV locally absent

Aphid predators!Pseudodorus clavatus

Syrphid flyLarvae are predacious

https://www.treknature.com/gallery/photo269910.htm

Lady beetlesAdults & larvae predacious

J. Penney

M. Quinn

https://commons.wikimedia.org/wiki/File:Harmonia_axyridis_larvae_2.jpg

M. Quinn

Cycloneda sanguinea Harmonia axyridis

Green lacewingsLarvae predacious

B. Newton

Drees

Citrus Whitefly, Dialeurodes citri•Serious pest in the 1900-1930’s

• No longer a serious problem thanks to introduced parasitoid, predatory arthropods, and parasitic fungi

Citrus whitefly eggs Whitefly nymphs- translucent, produce large amounts of honeydew (1st instar has legs, absent in later instars)

Both male and female adults are winged.

FDACS-DPI

Natural Enemies of Citrus Whitefly

Exotic parasitoid of Citrus Whitefly,

Encarsia lahorensis

Successfully established in Florida in 1977

Whitefly nymph with parasitoid larva and pupa

Whitefly Fungi

Aegerita sp.Aschersonia spp.

Effective with the right environmental conditions

Copper sprays inhibit growth of these “friendly fungi”

Foliage pest concerns in mature trees

• Pests that reduce the overall health of the tree

• Cause leaf and/or fruit drop

• Produce honeydew, promoting sooty mold development

Spider Mites

Citrus Red Mite (Panonychus citri)

Texas Citrus Mite (Eutetranychus banksi)

Spider Mites

• Dry conditions favor rapid population growth

• Natural enemies exist, but can’t keep up with populations under dry conditions

• Highest populations September – May (dry period)

• 5-10 spider mites per leaf is action level for treatment if populations are not in decline

• Higher percentage of males indicates population declining

Leaf drop caused by spider mites (January)

Male (long legs)Females (Short legs)

Many females, eggs present, few males = population rapidly growing

Black Scale, Saisettia neglecta

Brown Soft Scale, Coccus hesperidum

Cottony Cushion Scale, Icerya purchasi Green scale, Coccus viridis

Scale pests of foliage

Honeydew from scale insects deposited on leaves = sooty mold

Why do many Hemipterans produce honeydew?

• too much water can be a bad thing

• mechanism to cope with foods high in water content

Scale insects psyllids

ForegutTemporary storage and grinding of food

MidgutDigestion & absorption of nutrients into body

Alkaline pH ≥ 7

HindgutRe-absorption of water, salt & other nutrients before excretion of (dry) nitrogenous waste (frass)

Insect Digestive and Excretory Systems

honeydew producers

FC = filter chamber; used to pass water directly out the rectum

thus concentrating plant sap before it is absorbed into the insect

body

Insects and Mites associated with plant

diseases

Brief overview of biology…

Asian citrus psyllid – Diaphorina citri

First found in Florida June 1998

Citrus Greening Disease

Asian Citrus Psyllid Distribution (FL)

• First detected in dooryard citrus trees in south Florida in 1998

• subsequent finds in nursery plants (orange jasmine [Murraya paniculata]) in discount stores throughout the state

• psyllid well established in primary citrus growing areas of FL and cannot be eradicated

Picture taken 1.4.19 in CREC groves

After Asian citrus psyllid colonized SE Florida (red), it moved on Murrayapaniculata to other counties very rapidly.

Rapid movement made eradication unfeasible

Found in SE areas of Texas and Mexico and CA in 2008

The “Home Depot” Effect

egg adult in 2 weeks at 75-80°F

5 nymphal stages

Life cycle takes 15-47 days

10 generations / year

Asian Citrus Psyllid (ACP)

• 3-4 mm in length

• mottled wings

• Adult psyllids can feed on both new and mature leaf flushes; prefer young leaves

• When young leaves not available, adult psyllids are found on underside of mature leaves feeding on leaf midvein

• Mean longevity of females increases with decreasing temperature within 59-86°F / 15-30°C

Adult ACP

Adults gather at newly

emerging growing tips and on

young flushes, feed and mate

Factors affecting psyllid populations

The two main factors regulating psyllid population growth are:

1.Temperature

2.New leaf flush (resource availability)

Adults oviposit ONLY on young leaf

flush

Eggs are about 0.3 mm long and

almond shaped

Eggs are pale when deposited, turn

yellow then orange as they mature.

Often difficult to see without hand

lens

Asian Citrus Psyllid Eggs

**

*

*

Duration of EGG STAGE (in days) and HATCH SURVIVAL

Temp (°F/°C) Days to hatch Survival

50°F / 10°C 0 0

59°F / 15°C 9.74 ± 0.23 84.5%

68°F / 20°C 7.03 ± 0.11 89.4%

77°F / 25°C 4.15 ± 0.07 95.5%

82°F / 28°C 3.46 ± 0.09 96.2%

86°F / 30°C 3.29 ± 0.06 93.2%

91.4°F / 33°C 0 0

Data from Liu & Tsai, 2000. Ann. Appl. Biol. 137:201-216.

Psyllid developmental times (in days)

Temp (°F/°C) Egg to adult

50°F / 10°C 0

59°F / 15°C 49.3± 0.4

68°F / 20°C 28.8± 0.5

77°F / 25°C 17.0± 0.2

82°F / 28°C 14.1± 0.2

86°F / 30°C 16.3± 0.3

91.4°F / 33°C 0

Data from Liu & Tsai, 2000. Ann. Appl. Biol. 137:201-216.

• 0.3 mm long in the first instar

• 1.6 mm long as fifth instars

• Nymphs are yellow in color with red eyes and visible wing pads in larger nymphs

Asian Citrus Psyllid Nymphs

• early nymphal stages easily mistaken for aphids • white carbohydrate secretions provides an easy means of

distinguishing from aphids at a distance.

Asian Citrus Psyllid Nymphs

Nymphal developmental times (in days)

Temp (°F/°C) Total nymphal stages Survival (%)

50°F / 10°C Failed to develop beyond 3rd instar

0

59°F / 15°C 39.6 ± 0.3 61.9

68°F / 20°C 21.8 ± 0.4 69.8

77°F / 25°C 12.8 ± 0.2 75.4

82°F / 28°C 10.6 ± 0.2 83.9

86°F / 30°C 13.0 ± 0.3 73.7

91.4°F / 33°C Failed to develop beyond 4th or 5th instar

0

Data from Liu & Tsai, 2000. Ann. Appl. Biol. 137:201-216.

Low temperature developmental thresholds

1st instar 53°F (11.7°C)

2nd instar 51°F (10.7°C)

3rd instar 50°F (10.1°C)

4th instar 51°F (10.5°C)

5th instar 52°F (10.9°C)

Effects of Cold Weather on Psyllid Populations

January 2-3, 2008

CREC Research Grove8-10’ ‘Hamlin’ orange

Evaluating psyllid mortality• Caged 600 psyllids (30 psyllids/tree)

• Cages placed in plots with and without freeze protection (irrigation)

• Inside vs outer canopy

Factors Evaluated

• Freeze protection vs. no freeze protection

• Effects of location of psyllids in tree canopy

• Recorded leaf temperatures and trunk base temperatures every 2 hours

• Data loggers within cages recorded temps every 15 mins.

• Weather station data also collected

CREC Jan 3, 2008 (8:00 AM)

CREC Temps (Jan 2-3, 2008)

10+ hrs below freezing

Effects of Freeze Protection on Psyllid Survival

F = 3.55P = 0.076

Mortality of Psyllids Located Inside and Outside Canopy

F = 2.31P = 0.1455

Overall psyllid mortality from freezingAverage mortality rate: 60.8%

Minimum mortality observed: 20.7%• Lowest mortality in freeze protection plots

• With no freeze protection lowest 41.2%

Maximum mortality observed: 86.8%

Conclusions

• At CREC location sustained freezing temperatures reduced psyllid populations an average of 60%

• Psyllid mortality likely to vary by location based on duration and intensity of cold

• Cold temperatures in the citrus growing regions of Florida are not enough to reduce the need for early season psyllid control

Psyllid feeding damage

In the absence of the greening pathogen, psyllid control previously targeted young trees to protect new growth from damage that results in reduced tree growth.

Dieback of new growth

Witches broom effect

Psyllid nymphs produce waxy secretions similar to aphid or scale insect honeydew

Sooty mold - growing on sticky residues from secretions from psyllid nymphs

Monitoring Psyllid PopulationsImportant to monitor when new flush is available

Critical time is spring and fall when temperatures are cooler and flush is abundant

Check expanding terminals for aggregations of psyllids

Adult psyllids found on underside of leaves near leaf midvein when no new flush is available

Eggs tucked away in very young, newly forming leaves and leaf buds.

Monitoring Psyllid Populations

Inspect new leaf and shoot flushes of citrus and citrus relatives such as orange jasmine, Murraya paniculata. Look for white honeydew and leaf distortion on new leaf flush and shoots.

Monitoring Psyllid Populations

Biological Control of Psyllids

There are numerous natural enemies of psyllids present that suppress psyllid populations, especially in the summer and fall

Use of broad spectrum foliar insecticides will present a problem in maintaining populations of the natural enemies of psyllids and other potential pest species

Natural Enemies of Juvenile D. citri in Florida

SpidersHibana velox (Anyphaenidae) Chiracanthium inclusum (Clubionidae)Hentzia palmarum (Salticidae)Oxyopes sp. (Oxyopidae)

Ladybeetles (Coccinellidae)Curinus coeruleusCycloneda sanguineaExochomus childreniHarmonia axyridisOlla v-nigrum

Green Lacewings (Chrysopidae)Chrysoperla rufilabrisCeraeochrysa spp. (2 - 3)

Hoverflies (Syrphidae)Allograpta obliqua

Brown Lacewings (Hemerobiidae)Micromus posticus

ParasitoidsTamarixia radiata

Hemiptera (Anthocoridae)Orius sp.

Ants (Formicidae)Dorymyrmex bureniPseudodmyrmex gracilis

Biological Control:

Olla v-nigrum

J. P. Michaud

Biological Control:Harmonia axyridis

Multicolored Asian ladybeetle

Tamarixia radiata• External Parasite• Originally from India• Mass reared & released by FDACS• Variable incidence in Florida

“Classical” Biological Control

Tamarixia radiata: life stages

Adult finding host

Adult laying egg Egg attached to abdomen of ACP

Larva attached to underside of ACP, consuming internal tissues

Pupa- will emerge through body of ACP

http://www.fftc.agnet.org/library/article/tn2001005.html#6

Tamarixia Survey 2006-07(old, pre-ACP area-wide management attempts)

• surveyed major citrus growing areas

• establishment of Tamarixia?

• parasitism rates?

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Tamarixia survey 2006-07

average parasitism rates less than 20% throughout most of the season

Additional Parasitoid Introductions

• Diaphorencyrtis aligarhensis• Encyrtidae

• Originally released along with T. radiata; failed to establish

• Additional releases made with parasitoids from geographic regions with climates more similar to FL

Chemical Control of the Asian Citrus Psyllid

Recommendations updated annually in Citrus Production Guide*

*Current chapter:https://crec.ifas.ufl.edu/media/crecifasufledu/extension/plant-pathology-/florida-citrus-production-guide/pdf/ACP-and-Leafminer.pdf

Soil-applied Insecticides for Psyllid Control

Young trees (< 6-8 feet tall)

• Soil applied systemic insecticides are most effective (imidacloprid, thiamethoxam, clothianidin)

• must be applied about 2 weeks prior to flush for best results

• in sandy soils, can be washed away if heavy rains occur with 12 -24 hr post treatment

• have fewer negative effects on natural enemy populations

Foliar-applied Insecticides for Psyllid Control

Use on both young and mature trees:

• best to target psyllids before new flush present

•Control adults before eggs laid

• typically broad-spectrum products

• most have negative effects on natural enemies

•Will discuss in more detail later (next lecture)

Brevipalpus mites and Citrus Leprosis

Tenuipalpidae

• Over 622 species in 26 genera worldwide

• False spider mites, flat mites

• Primarily found in tropical/subtropical areas

• Genus Brevipalpus most important economic group

Egg

Larva

Photochrysalis

Protonymph

Deutochrysalis

Deutonymph

Teliochrysalis

Adult Female

Adult Male

50-60/female

Comparative developmental rates, egg production and adult longevity of Brevipalpusphoenicis and Panonychus citri at 270 C

(Duration in days)

B. phoenicis P. citri

Egg 6.0 3.4Larva 4.8 1.9Protonymph 4.8 1.6Deutonymph 4.9 2.3Egg-Adult 20.7 12.0Adult Longevity 20.4 -

Host Oroxylum indicum Citrus sp.

Authors: Beavers & Hampton 1971; Lal 1978; Saito 1979

Brevipalpus californicus, B. obovatus and B. phoenicis

Two problems:•Mites can develop to large numbers on various

host plants. They have toxic saliva that can result in feeding injuries to citrus and other economic crops.

•Mites are vectors of one or more unassigned Rhabdoviruses in citrus, coffee, passion fruit, orchids and numerous woody ornamental

plants.

Brevipalpus spp.

Examples of direct feeding damage – The following

images ARE NOT LEPROSIS

Leprosis

• Problem on sweet orange varieties

• Caused by virus that is not systemic in plant

• B. phoenicis is the only confirmed vector

• Miticide costs on Brazilian citrus exceed 90 million US dollars per year (Omoto 2000)

• Currently not in Florida (is present in Mexico)

Citrus Leprosis (symptoms)

• Chlorotic leaf lesions becoming brown with or without necrotic centers

• Flat or slightly raised necrotic areas on twigs and leaves

• Flat or depressed lesions on fruit with concentric patterns and gumming

• Abscission of leaves and fruit and twig dieback due to extensive lesion development

Leprosis: Fruit Lesions

Leprosis : Fruit Drop

Sharpshooters and Citrus Variegated Chlorosis

Citrus Variegated Chlorosis• Causal agent Xylella fastidiosa, a xylem limited

bacteria

• Found in Brazil, Argentina, Paraguay, and more recently identified in Costa Rica

• Transmitted by sharpshooter leafhoppers

• Infects most citrus cultivars

Next Lecture…

• How to develop a comprehensive pest management program in the presence of ACP/HLB

• Insecticides and modes of action