Biologia 68/2: 330—336, 2013Section ZoologyDOI: 10.2478/s11756-013-0157-7

Arthropod community of dandelion (Taraxacum officinale) capituladuring seed dispersal

Alois Honěk1, Pavel Štys2 & Zdenka Martinková1

1Crop Research Institute, Drnovská 507, CZ-16106, Praha 6 – Ruzyně, Czech Republic; e-mail: honek@vurv.cz2Charles University, Faculty of Sciences, Viničná 7, CZ-12000 Praha 2, Czech Republic

Abstract: Dandelion (Taraxacum officinale) is an abundant Asteraceae species of grassland and vasteland stands. Throughthe vegetative season each plant produces a number of short-lived inflorescens. Final stage of inflorescence developmentis seed dispersal that lasts 2 days. Despite its ephemeral persistence, inflorescences at this period host abundant fauna.In 2005–2010 the inflorescences were collected in regular intervals in May – October, at Prague-Ruzyně and selected sitesof western Czech Republic. Typical fauna consist of Heteroptera adults and larvae (34 species), phytophagans feedingon receptacle and seeds (mainly Miridae, Pentatomidae, Rhopalidae) and predators consuming thrips (Anthocoridae). Thecomposition of Heteroptera fauna varies through the vegetative season, and its abundance decreases with increasing altitudeof the locality. Other fauna are relics of species consuming seeds in the post-flowering phase of inflorescence maturation(mainly Thysanoptera) and occasional visitors with no trophic relationship to dandelion (Coleoptera, Diptera, Hymenoptera,Araneae). The reasons for association of phytophagous Heteroptera and dandelion may be preferences for seed consumptionand chemicals present in plant tissues and possibly used for sequestration of aposematic substances.

Key words: Asteraceae; Heteroptera; Coleoptera; insect; weed; food preference

Introduction

Dandelion (Taraxacum officinale Weber ex Wiggers) isan abundant annual herbaceous plant native to centralEurope. It colonizes disturbed sites, pastures, trampledgrasslands, sparse stands of permanent crops, orchardsand urban habitats (Pavlů et al. 2007). Introduced intoNorth America, it became an important weed of an-nual crops in no-tillage systems (Hacault & Van Acker2006). Reproduction is achieved mainly through wind-born seed (Solbrig & Simpson 1974) dispersed from in-florescences consisting of single capitulum on a leaflesspeduncle. Development of inflorescence is quick: threeday flowering is followed by 8–13 day seed maturationin closed capitula and 2–3 days period of seed disper-sal (Gray et al. 1973; Martinková & Honěk 2008; Mar-tinkova et al. 2011). Dandelion flower throughout thevegetative season with the peak in spring and late sum-mer (Sterk & Luteijn 1984).While arthropod fauna of seed maturing capitula

was listed in detail by Honěk et al. (2005), arthro-pods present during flowering (Percival 1955; Free 1968;Munoz & Cavieres 2008) and seed dispersal stage (vonHofsten 1954; Fox & Caldwell 1994) were studied occa-sionally. Consequently, there is no data on composition,seasonality and geographic differences of the fauna in-habiting inflorescences at the period of seed dispersal.Although the stage of seed dispersal is ephemeral, ourpilot study indicated that fauna inhabiting dandelioninflorescences at this period is rich and specific. The

information on this trophic guild is important becauseconsumers may cause seed mortality and thus influencepopulation dynamics of dandelion.In this paper we address the (i) composition of

arthropod fauna aggregated in dandelion inflorescencesat the period of seed dispersal, its (ii) seasonality and(iii) geographic variation.

Material and methods

Study sitesThe sampling plan was designed to reveal seasonal and an-nual variation in fauna aggregated on dandelion inflores-cences at the time of seed dispersal. The core study wasmade in the surroundings of the Crop Research Institute atPrague-Ruzyně (midpoint 50◦05′11′′ N, 14◦18′10′′ E, alti-tude 340 m a.s.l.). This area of c. 0.5 km2 site is a mosaic ofexperimental fields and garden lawns bordered by deciduoustree hedges. The study was made in dandelion stands flow-ering throughout the vegetative season and growing on fivedry grassy plots routinely cut 2–3 times per year. The sam-pling was continued in 3–10 day intervals, in 2005 (19 sam-pling days), 2006 (10 samplings), 2008 (5 samplings), 2009(31 samplings) and 2010 (21 samplings), each year betweenApril 24 and October 21. A separate study should reveal ge-ographic variation in the composition of Heteroptera com-munities along a lowland – mountain transect. Dandelioninflorescences were collected at insolated grassland or fallowfield sites, on May 8, 2009 at nine sites along Transect 1 fromČelákovice (50◦20′40′′ N, 14◦44′10′′ E) to Prague-Satalice(50◦07′31′′ N, 14◦34′27′′ E, 22 km, altitude 170–270 m a.s.l.)and on May 9–10, 2009 at 18 sites along Transect 2 from

c©2013 Institute of Zoology, Slovak Academy of Sciences

Arthropod community of dandelion inflorescences 331

Fig. 1. Numbers of phytophagous (shaded bars) and carnivorous species (white) of Heteroptera in the total sample of Praha-Ruzyně,2009–2010. Insert: Proportion of phytophagous Heteroptera families represented by phytophagous species probably feeding on dande-lion. Based on adults of the total sample of Praha-Ruzyně, 2005–2010. Indicated clockwise from the top of the figure: MIRI – Miridae,RHOP – Rhopalidae, PENT – Pentatomidae, RHYP –Rhyparochromidae, SCUT – Scutelleridae.

Pardubice (50◦00′56′′ N, 15◦46′42′′ E) to Hlinsko (49◦46′13′′

N, 15◦55′44′′ E) and Polička (49◦43′05′′ N, 16◦17′11′’ E, 80km, altitude 220–730 m a.s.l.). Supplementary sampling wasmade at ten sites of western Czech Republic (Bohemia), in2005–2010.

Sampling insectsDandelion inflorescences with their arthropod fauna wereharvested on sunny, calm (wind velocity <2 m s−1) andwarm days, between 9:00–17:00 h of Central EuropeanTime. This restriction was accepted to maximize samplingefficiency since insects may leave inflorescences under un-favourable conditions. At each site the inflorescences weresampled from a 500–1000 m2 area. The inflorescences withfully opened bracts exposing seeds for dispersal were ap-proached while avoiding cast shadow on them, quicklygrasped and plucked together with 1 cm of the upper stalk.Quick hand picking assured collecting the inflorescenceswith all their fauna. Minimum 50 inflorescences were sam-pled at each date and site, in 2009 the transect study com-prised 200 inflorescences at each site. A sample of inflores-cences from one site was put into a plastic bag, preserved at5◦C until species identification when arthropods were pickedby aspirator, killed and dry mounted or preserved in alcohol.This study deals with phytophagous Heteroptera (all years)or all Heteroptera and other groups of arthropods (2009and 2010). All Heteroptera were identified to family level,selected adults of 2005 and all adults of 2009–2010 to specieslevel, larvae mostly to genera. Other arthropods were iden-tified to species or genera. The materials were identified bythe authors or expert specialists (see Acknowledgements).

Results

HeteropteraHeteroptera was the dominant group inhabiting dande-lion inflorescences. Thirty four species of Heteropterabelonging to 10 families were established during the sixyears of the study (Table 1). Twenty nine (85%) specieswere shared between the core study area at Praha-Ruzyně and other sampled sites of western Czech Re-public, 5 species were captured in May 2009 only at sitesof Transect 1 (Rhyparochromus vulgaris, Holcostethusvernalis), Transect 2 (Nysius senecionis, Cymus glandi-color ) and site of Javory (50◦44′08′′ N, 14◦08′37′′ E)in northern Bohemia (Eurygaster testudinaria).The assemblage collected at Praha-Ruzyně repre-

sents a typical example of Heteroptera fauna present atsites of western Czech Republic. The sample of 2009–2010 when all individuals were identified to species (n= 551) contained adults of 21 species (Fig. 1) of whichthe most abundant was the Anthocoridae species Oriusniger (n = 292) which represented 53% of the totalsample. However, abundance of this species varied be-tween years and was nearly 6 times greater in 2009 (11individuals 100 inflorescence−1) than in 2010 (2 indi-viduals 100 inflorescences−1). Further dominant weretwo Miridae species, Lygus pratensis (n = 72) and L.rugulipennis (n = 64). One Pentatomidae (Dolycorisbaccarum) and five Rhopalidae species were mediumabundant (n = 10–23) while twelve remaining species

332 A. Honěk et al.

Table 1. Species of Heteroptera captured through 2005–2010 and their ecological characteristics based on adult preferences. Somelarvae of Carpocoris, Eurygaster, Lygus, Nabis and Stictopleurus were not identified to species.

Habitat 2) Food 3)

Family and species 1) Host plantE H A F Pr Ph

AnthocoridaeOrius majusculus (Reuter, 1879) L * * POrius niger (Wolff, 1811) L * PCymidaeCymus glandicolor Hahn, 1832 4) * O,s Carex, Juncus, LuzulaLygaeidaeNysius senecionis (Schilling, 1829) 4) * * O AsteraceaeMiridaeAdelphocoris lineolatus (Goeze, 1778) * O FabaceaeLygus pratensis (L., 1758) * * * PLygus rugulipennis Poppius, 1911 * * PLygus wagneri Remane, 1955 * * POrthops basalis (A. Costa, 1853) * O ApiaceaePlagiognathus chrysanthemi (Wolff, 1804) * PNabidaeAptus mirmicoides (Costa, 1834) * * * PNabis ferus (L., 1758) * PNabis pseudoferus Remane, 1953 * PPentatomidaeCarpocoris fuscispinus (Boheman, 1851) * P Asteraceae, Apiaceae, ScrophulariaceaeCarpocoris purpureipennis (DeGeer, 1773) * P Asteraceae, Apiaceae, ScrophulariaceaeDolycoris baccarum (L., 1758) L * * P Asteraceae, Apiaceae, Rosaceae, Scrophulariaceae,Eurydema oleracea (L., 1758) * O BrassicaceaeHolcostethus vernalis (Wolff, 1804) 4) * * P,s Asteraceae, Apiaceae, Fabaceae, VerbascumPalomena prasina (L., 1761) LL * * PPalomena viridissima (Poda, 1761) LL * * PPyrrhocoridaePyrrhocoris apterus (L., 1758) L * * O,s Malvaceae, Robinia, TiliaRhopalidaeCorizus hyoscyami (L., 1758) * PLiorhyssus hyalinus (F., 1794) * O AsteraceaeRhopalus parumpunctatus Schilling, 1829 * PRhopalus subrufus (Gmelin, 1790) * P Geraniaceae, LamiaceaeStictopleurus abutilon (Rossi, 1790) * O AsteraceaeStictopleurus crassicornis (L., 1758) * * O,s AsteraceaeStictopleurus pictus (Fieber, 1861) * O AsteraceaeStictopleurus punctatonervosus (Goeze, 1778) * O AsteraceaeRhyparochromidaeRhyparohromus pini (L., 1758) L * P,sRhyparohromus vulgaris (Schilling, 1829) 4) * P,sTrapezonotus arenarius (L., 1758) LL * P,sScutelleridaeEurygaster maura (L., 1758) * O,s PoaceaeEurygaster testudinaria (Geoffroy, 1785) 4) * O,s Poaceae, Cyperaceae, Juncaceae

Explanations: 1) L – larvae found, LL – only larvae found; 2) E – epigeic, H – herbicolous, A – arboricolous, F – fruticolous, * –preferred habitat; 3) Pr – predator, Ph – phytophagan, P – polyphagan, O – oligophagan, s – definite preference for seeds in adultstage, Host plant – preferred plant taxon; 4) species not present at Praha – Ruzyně sample.

were rare (n = 1–8). Three Pentatomidae species, Eu-rydema oleracea, Palomena prasina and P. viridissima,and the Rhyparochromidae speciesTrapezonotus are-narius were established only as larvae. Adults of threespecies of Miridae, Adelphocoris lineolatus, Lygus wag-neri and Orthops basalis, and larvae of the Pyrrhocori-dae species Pyrrhocoris apterus were found in 2005–2008. The sample of phytophagous Heteroptera proba-bly feeding on dandelion and collected over the whole2005–2010 period (n = 411 adults) was dominatedby Miridae (46% individuals of the total sample) fol-lowed by Rhopalidae (25%), Pentatomidae (19%), Rhy-parochromidae (6%) and Scutelleridae (4%) (Fig. 1).The number of species was highest for Rhopalidae(8 species, 28% of the total of 29), followed by Pen-

tatomidae and Miridae (both 6 species, 21%) (Ta-ble 1).The composition of phytophagous Heteroptera

community changed with the course of the season andthis change was similar in different years of the study.The percentage of Pentatomidae in the sample of par-ticular months decreased and percentage of Miridae in-creased with the course of the season, Rhopalidae wererelatively abundant in the spring (May, June) and inthe autumn (October) and Rhyparochromidae in July.Other families together represented always less than20% of the total monthly sample (Fig. 2A). The lar-vae of phytophagous Heteroptera were found in June– September, with maximum in July when they madeup 38% of the total population (Fig. 2B). Polyphagous

Arthropod community of dandelion inflorescences 333

Fig. 2. Seasonal variation in the frequency of phytophagous Heteroptera. A – proportion of abundant families in the total sample ofadults and larvae. B – Proportion of adults and larvae in the total sample of all families. Figures above bars indicate sample size inparticular months (total n = 411). Cumulated data of Praha-Ruzyně, 2005–2010.

Anthocoridae predators (not shown in Figs 1 and 2)dominated the Heteroptera community in August andSeptember. In 2009 when remarkably abundant, An-thocoridae (mostly Orius niger) represented 69% of thetotal Heteroptera (n = 398). Seasonal change in abun-dance of families was determined by occurrence of par-ticular species (Fig. 3). Orius niger (Anthocoridae), L.pratensis and L. rugulipennis (Miridae) occurred in theautumn. Four Rhyparochromidae species and Pentato-midae D. baccarum occurred throughout the season.Although species composition of Heteroptera com-

munity of Prague-Ruzyně and of other sites of west-ern Czech Republic appear similar, overall Heteropteraabundance (all species together) at 27 sites along al-titudinal Transects 1 and 2 decreased with increasingaltitude (Fig. 4).

Other arthropodsAt least 33 species of arthropod other than Hetero-ptera were sampled from dandelion inflorescences in2009–2010 (Table 2). Abundant were adults and lar-vae of species of seed predators, Olibrus bicolor andGlocianus punctiger (Coleoptera) and Thrips hukki-neni (Thysanoptera) which dominate the fauna dur-ing the foregoing stage of seed maturation in closedcapitula (Honěk & Martinkova 2005; Honek et al.

2005). Other species are a collection of phytophagousand predatory species dominated by Coleoptera (22species of 14 families). Only Sitona lineatus adultswere abundant (August – September, 2.2 individ-uals 100 inflorescences−1). Other species, Atomariasp., Cryptocephalus fulvus, Longitarsus sp., Melanoph-thalma transversalis, Meligethes aeneus and Oedemeraflavipes were found regularly but rarely. Further presentwere Diptera (Syrphid larvae and several undeterminedspecies of small Brachycera adults), ants (Lasius nigerat Prague-Ruzyně, different species at other localities)and Araneae (eight species common on herbaceousvegetation). These species occurred in small numbersthroughout vegetative season.

Discussion

The duration of seed dispersal stage in dandelion isephemeral, lasting 1–3 days (median 2 d) (Martinková& Honěk 2008). However, at many sites dandelionsflower over the whole season and may produce 150–250capitula m−2 (Honek et al. 2005). Seed is thus avail-able for long periods in copious quantity and may thusbecome interesting food resource whose exploitation isprofitable. At many sites the capitula are aggregatedand could be reached by short distance dispersal.

334 A. Honěk et al.

Fig. 3. Seasonal occurrence of abundant species of Heteroptera:A – O. niger, B – L. pratensis, C – L. rugulipennis, D – S.crassicornis, E – S. punctatonervosus, F – C. hyoscyami, G –R. parumpunctatus, H – D. baccarum. Cumulated data of 2009–2010, each bar represents occurrence of at least one individual ofa species on the particular date.

The study revealed that insect fauna of dandelioninflorescences at the stage of seed dispersal consist ofthree groups of species. Two groups include Heteropteraspecies. The first species rich group is the guild of phy-tophagous (mainly polyphagous) Heteroptera trophi-cally associated with dandelion. The species are typ-ical not only for western Czech Republic: D. baccarum,Corizus hyoscyami, Stictopleurus crassicornis, Palo-mena prasina are associated with dandelion in Sweden(von Hofsten 1954). Occurrence of the South EuropeanCarpocoris pudicus mentioned in that study is impos-sible in Scandinavia (Tamanini 1959) and was prob-ably confounded with Carpocoris purpureipennis. He-teroptera fauna of dandelion inflorescences at disper-sal is typical, not a random sample of phytophagousheteroptera are present at the site (as it would bein absence of any specific attraction for using inflo-rescences). This appears first from absence of severalspecies frequent in similar herbaceous habitats includ-ing Anthocoris nemorum, A. pilosus (Anthocoridae),Deraeocoris ruber, Neolygus spp., Stenodemini spp.,Calocoris spp., Chlamydatus spp. (Miridae), Nabis ru-gosus (Nabidae), Aelia acuminata (Pentatomidae) andScolopostethus spp. (Rhyparochromidae). Second, it ap-pears from aggregated presence of a few taxa only, L.pratensis, L. rugulipennis, Plagiognathus chrysanthemi(Miridae), Stictopleurus spp., C. hyoscyami, Rhopalusparumpunctatus (Rhopalidae), D. baccarum and Eu-rygaster maura (Pentatomidae). The trend of decreas-ing abundance of pooled Heteroptera species observedalong a lowland to highland transect is uneasy to ex-plain. It may reflect geographic variation in Heteropteraabundance but also delay in seasonal course of vegeta-tion development at sites of higher altitude, at a roughestimate 7–10 days. This difference may slow emigra-

Fig. 4. Abundance of Heteroptera (all phytophagous species together) at 27 sites situated along Transect 1 and Transect 2, sampledon May 8–10, 2009. Number of individuals per 100 inflorescences ploted against altitude of the site.

Arthropod community of dandelion inflorescences 335

Table 2. Arthropod species other than Heteroptera captured in dandelion inflorescences, their development stage and food specialization(data of 2009–2010).

Family Species 1) Stage 3) Food 4)

ColeopteraBruchidae Bruchidius marginalis (F., 1775) A PhBuprestidae Anthaxia nitidula (L., 1758) A PhCoccinellidae Coccinella septempunctata L., 1758 A Pr

Scymnus interruptus (Goeze, 1777) A PrTythaspis sedecimpunctata (L., 1758) A Pr

Cryptophagidae Atomaria sp. A PhCurculionidae Apion violaceum Kirby, 1808 A Ph

Ceutorhynchus obstrictus (Marsham, 1802) A PhGlocianus punctiger (Gyllenhal, 1837) * A,L PhPhyllobius sp. A PhSitona lineatus (L., 1758) A Ph

Elateridae Agrypnus murinus (L., 1758) A PhChrysomelidae Cassida vittata Villers, 1789 A Ph

Cryptocephalus fulvus Goeze, 1777 A PhLongitarsus sp. A Ph

Lathridiidae Melanophthalma transversalis (Gyllenhal, 1827) * A PhMordellidae Mordellistena sp. A PhNitidulidae Meligethes aeneus (F., 1775) A PhOedemeridae Oedemera flavipes (F., 1792) A PhPhalacridae Olibrus bicolor (F., 1792) * A,L PhScarabaeidae Oxythyrea funesta (Poda, 1761) A PhStaphylinidae Tachyporus hypnorum (F., 1775) A PhDipteraSyrphidae Syrphidae sp. * L PrHymenopteraFormicidae Lasius niger (L., 1758) A Ph,PrThysanopteraThripidae Thrips hukkineni Priesner, 1937 * A,L PhAraneaeClubionidae Cheiracanthium erraticum (Walckenaer 1802) A,L PrDictynidae Dictyna sp. 2) A,L PrLinyphiidae Erigone dentipalpis (Wider, 1834) A,L PrPhilodromidae Philodromus sp. 2) A,L PrTheridiidae Steatoda phalerata (Panzer, 1801) A,L Pr

Theridion sp. 2) A,L PrThomisidae Misumenops tricuspidata (F., 1775) A,L Pr

Xysticus sp. 2) A,L Pr

Explanations: 1) * species present also inside closed inflorescences filled with maturing seeds (Honěk et al. 2005); 2) Only immatureindividuals available for identification; 3) A – adults, L – larvae; 4) Ph – phytophagan, Pr – predator.

tion of Heteroptera from overwintering sites and delayoccupation of dandelion inflorescences.A guild of species occurs in dandelion inflores-

cences because of their host plant preference and mo-bility. During this study, adults and larvae of severalspecies of the families Miridae, Pentatomidae, Pyrrho-coridae and Rhopalidae were observed feeding in dan-delion inflorescences. The proboscis of some individu-als was inserted in seeds or receptacles, in most cases,however, the site of feeding was not determined becauseseed plumes screened the animal. The preferred food ofparticular species could be inferred from available dataon food specialization (Table 1). Some species are ap-parently specialized on seed-sucking. Seed is an ampleresource of nutrients exposed free for consumption andused by a lot of consumers. Before dispersal (Honek &Martinkova 2005) and after spreading of seed on theground (Honek et al. 2005) seed is vigorously eaten bymany predators (Honek et al. 2009). Seed may attractthe consumers also during the very short period of dis-persal. This is probably so in case of species which aretypical seed consumers but little attracted to dandelion.

An example are larvae of P. apterus which, following a 3day exposure, decreased germinability of dandelion seedfrom 75 ± 6.7% to 34 ± 19.8% (Z. Martinková and A.Honěk, unpubl.). The species may also prefer feeding onthe receptacle of dandelion inflorescences. As in otherTaraxacum species, the tissues of T. officinale are richin latex whose concentration varies with plant organ,age, season and nutrition (Nichiporovich & Bourovaya1938; Mashtakov et al. 1940; Krotkov 1945). The chem-icals present in dandelion tissues might be useful partic-ularly to species capable of its sequestration. Sequestra-tion is probably widespread in the usually aposematicLygaeidae: Lygaeinae (Duffey & Scudder 1974; Aldrich1988), and we could expect this phenomenon in speciesof other families as well. Particularly species of cladeswith predominanly reduced adult metathoracic glandsand/or external evaporatorial apparatus, and usuallywithout a pungent smell are likely candidates (Pyrrho-coridae, Rhopalidae). Besides preference for feeding ondandelion, mobility of seed feeders is also a pre-requisiteof occupying the ephemeral habitat of seed dispersingdandelion inflorescences. This is clear from dominance

336 A. Honěk et al.

of adults which represent the majority of heteropterancommunity even in periods of breeding, when larvaemust be in the total heteropteran fauna present at thesite more numerous than adults. In fact most species ofHeteroptera are good fliers (Lu et al. 2007) includingthose established in this study (Brown 1965; Šedivý &Honěk 1983).The second group of inhabitants of dandelion con-

sist of abundantly occurring Orius niger preying onTaraxacum-inhabiting T. hukkineni.Orius (Orius)nigeris the only frequently occurring predator with a dis-tinct trophic link to a phytophagous Thrips inhabit-ing Taraxacum. The association is probably not spe-cific but biotope-dependent since Orius (Orius) speciesprefer low vegetation in contrast to Orius (Heterorius)species preferring taller vegetation, shurbs and trees,and being often partly pollenophagous.The third group of inflorescence inhabitants is an

assemblage of occasional phytophagous or predaciousvisitors with weak or no relationship to their host plant.The reason for assemblage of fauna of other taxa isnot clear. Most species are probably occasional visi-tors. However, some species (e.g., S. lineatus) appearso massively that their presence is probably not drivenby chance.Dandelion inflorescences at the stage of seed dis-

persal host a specific arthropod community despite theephemerality of the food source. The typical speciesall belong to Hemiptera: Heteroptera. Most of themare associated with dandelion because of their troph-ical preferences (for seed and/or substances serving asprecursors of antipredatory semiochemicals) and highmobility. As a result, the fauna is more specific anddiversified than fauna of earlier development stage ofdandelion inflorescences.

Acknowledgements

We thank Stano Pekár for identification of Araneae, JiříSkuhrovec for identification of Curculionidae, and HelenaUhlířova, Ludmila Kreslová and Jana Kohoutová for ex-cellent technical assistance. AH and ZM were supportedby grants No. 526/09/1436 of the Czech Science Founda-tion and No. 0002700604 of the MZe CR, PŠ by grant No.206/07/507 of the Czech Science Foundation.

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Received June 1, 2011Accepted December 12, 2012