Picromerus bidens (Heteroptera: Pentatomidae) as predator of the Checkerspot Euphydryas aurinia (Lepidoptera: Nymphalidae)

2005·0.55 MB·

by  Martin Konvička

©EntomologicaFennica.16December2005
Picromerus bidens (Heteroptera: Pentatomidae) as predator
of the Checkerspot Euphydryas aurinia (Lepidoptera:
Nymphalidae)
MartinKonvicka,VladimirHula&ZdenekFric
Konvicka,M.,Hula,V.&Fric,Z.2005:Picromerusbidens(Heteroptera:Penta-
tomidae) as predator of the Checkerspot Euphydryas aurinia (Lepidoptera:
Nymphalidae).—Entomol.Fennica16:233–236.
The predatory bug Picromerus bidens is reported as a regular predator of the
MarshFritillaryEuphydryasauriniafromtheregionofwesternBohemia,Czech
Republic.Adultbugsattackpre-diapauselarvae,eitherexposedorhiddeninpro-
tectivesilkenwebs,andexhibitefficientbehaviour,includingreturningtoprevi-
ouslyattackedwebs.Weobservedpredationinsixoutof28andelevenoutof21
localpopulationsin2003and2004,respectively.Inaddition,weobservedtwo
attacksbynymphsonhandicappedadultbutterflies.PredationofMelitaeinaeby
Heteropteraseemstobeawidespreadphenomenon,andP.bidenscanactasa
substantialmortalityfactorinsmallcoloniesofE.aurinia.
M. Konvicka, Department of Ecology and Conservation Biology, Institute of
Entomology, Czech Academy of Sciences, Branisovska 31, CZ-37005 Ceske
Budejovice,CzechRepublic;E-mail:[email protected]
V. Hula, Department of Zoology, School of Agriculture, Mendel University,
Zemedelska1,CZ-61301Brno,CzechRepublic;E-mail:[email protected]
Z. Fric, Department of Zoology, School of Biological Sciences, University of
SouthBohemia,Branisovska31,CZ-37005CeskeBudejovice,CzechRepublic;
&DepartmentofEcologyandConservationBiology,InstituteofEntomology,
Czech Academy of Sciences, Branisovska 31, CZ-37005 Ceske Budejovice,
CzechRepublic;E-mail:[email protected]
Received29December2004,accepted16February2005
1.Introduction
spot]populationdynamicsislargelyunknown,or
havebeenstudiedonly atafewlocations”.The
Checkerspot butterflies (Melitaeini) have be- reviewmentionsonlytwoinsectpredatorsofthe
comeestablishedasamodelsystemforawidear- Marsh Fritillary Euphydryas aurinia (Rottem-
rayofecologicalphenomena.Still,arecentsyn- burg, 1775): Poecilus versicolor (Coleoptera:
thesis by Ehrlich and Hanski (2004) points to Carabidae)andabug,citingWilkinson(1907)for
some gaps in understanding their biology. One bothrecords.Thisscarcityofinformationissur-
relatively unexploredfieldisthenaturalhistory prising, because the ecology of E. aurinia has
of checkerspots’predators. In their review, Van been intensively studied (e.g., Warren 1994,
Nouhuys and Hanski (2004) state that “general Wahlberg et al. 2002, Anthes et al. 2003, Kon-
importanceofnaturalenemiesfor the[checker- vickaetal.2003,Wangetal.2004).Clearly,there
234 Konvickaetal. (cid:127) ENTOMOL.FENNICAVol.16
stillisaneed“tofurtherstudythenaturalhistory quireadifferentmethodofsearchesthanjustzig-
andhostrangesofthepredatorsandparasitoids” zagging the localities. Therefore, we only re-
(VanNouhuys&Hanski2004). cordedifwehadobservedpredationpersite,and
Wereporthereourobservationsofpredation sowedonotknowtheexactnumbersofthepre-
bythebugPicromerusbidens(Linnaeus,1758) dationoccasionsbythebugs.
on both pre-hibernation larvaeand adult butter-
fliesofE.aurinia.
3.Results
2.Materialandmethods 3.1.Predationonlarvae
The distribution of E. aurinia in the Czech Re- Predation by the bug was observed every year,
publicisrestrictedtowesternBohemia,whereit butrecordedindetailonlyin2003and2004.At-
forms relatively small local populations (”colo- tacksbythebugwereobservedatsixoutof28oc-
nies”)restrictedtowetmeadowsandnon-inten- cupiedcoloniesin2003(21%),andatelevenout
sivepastures.Closelyadjoiningcoloniesarein- of21coloniesin2004(52%).Thecolonieswere
terconnected by adult dispersal and exhibit a typically medium- to large-sized (> 20 larval
metapopulation dynamics (Hula et al. 2004). webs),butinonecasein2004,weobservedpre-
AdultbutterfliesareonwingsfromlateMayuntil dationwithinanisolatedandextremelysmallcol-
lateJune.Femaleslaybatchesofeggsonleaves ony(19kmfromtheclosestsite,sixlarvalwebs).
ofSuccisapratensis,andlarvaefeedonthatplant The bugs attacked both exposed caterpillars
communally in loose silk-woven nests until hi- and,particularlyincoolerdays(<15°C,overcast
bernation. Prior to hibernation, they form more sky),inactivecaterpillarshiddeninsilkenwebs.
compacthibernationnests.Posthibernationlar- When feeding on exposed caterpillars, the bug
vaelivesolitarily. typically approached the larval mass, stalked a
We have studied the species from 2002 on- larva with proboscis, walked a few centimetres
wards,applyingannualcountsoflarvalwebsat away and sucked with its proboscis protruding
all known sites, combined with mark-recapture onwards (Fig. 1). The larvae tried to escape by
counts ofadults within asystemofseven inter- wigglingtheirbodies,butoutofsomefiftyobser-
connected colonies (Hula et al. 2004). Annual vations, the efforts never succeeded. After con-
numbersofoccupiedcoloniesrangedfrom21to sumingtheprey,thebugtypicallyreturnedtothe
28(mean=23.3),theirsizesrangedfromsingle larvalgroupandsingledoutanothercaterpillar.In
nesttoaboutonehundrednests(withannualme-
dians between ten and twenty nests). Annual
numbers of adults and larval webs exhibited a
closecorrelation.
Theobservationsofpredationoflarvaeorigi-
nated during counts of larval webs, conducted
eachyearduringthefirstweekofSeptember.Vis-
iting all colonies takes about a week. The time
spentatonecolonysitevariesfromtwentyper-
son-minutestoaboutfiveperson-hours,depend-
ingoncolonysize.Theattacksonadultswereob-
servedduringthemark-recapturestudies,which
consistedofdailymarkingofbutterfliesbyoneto
threepersons,coveringtheentireadultflightpe-
riod(detailsinHulaetal.2004). Fig.1.AdultPicromerusbidenspreyingonlarvaof
Theautumncountsoflarvalwebswerecon- Euphydryasaurinia.Notethesilkenmeshingoflarval
ductedtomonitorpopulationchangesandwedid webintheright.EnvironsofKarlovyVary,westernBo-
notrecordtheexactnumbersofbugs.Itwouldre- hemia,2September2003.©V.Hula.
ENTOMOL.FENNICAVol.16 (cid:127) HeteropteranpredatorofEuphydryasaurinia 235
Fig.2.NymphofPicromerusbidens
feedingonadultEuphydryasaurinia.
Thebutterfly,stillalive,washanging
fromaspiderweb.Bochovnear
KarlovyVary,westernBohemia,18
June2003.©V.Hula.
onecase,weobservedfivesuchreturns.Whenat- important food source in early autumn, when
tackinglarvaehiddenintheweb,thebugfirstex- onlyafewlarvaeofotherspeciesoccurinhigh
ploredwebsurface,tryingtolocateanopening. densities. The bug attacks the larvae quite effi-
Inthreecases,itpuncturedtheencasingsilkand cientlyandvisitsasinglelarvalgrouprepeatedly.
pokeditsprobosciswithinthewebforafewsec- Hence,itmightactasasubstantialmortalityfac-
onds, until it pierced a larva. One larval group tor.Althoughitisunlikelytobeathreattothesur-
wasusuallyattackedbyasinglebug,butinone vivaloflargecolonies,itmightdepletesmallpop-
case,threebugsexploitedoneweb. ulations,suchastheoneconsistingofsixlarval
webs.Weobservedattackedadultbutterfliesonly
whendamagedoralreadyentrapped.
3.2.Predationofadults Predationby Heteropterahasbeenobserved
in other Melitaeini as well. Van Nauhuys and
Observed twice, in both cases on handicapped Hanski(2004)listpredationonneonateEuphy-
butterflies.In2003,anymphofthebugstalkeda dryas gilletti (Barnes, 1897) by unspecified
butterflythatlooselyhangedfromalow-situated Miridae,andpredationonMelitaeacinxia(Lin-
spider’sweb,stilltryingtoescape.Wecaptured naeus,1758)byPentatomidae.VrabecandJindra
the bug while it fed on the butterfly and photo- (1998) reported substantial larval mortality of
grapheditwhilefeeding(Fig.2).In2004,ween- Euphydryasmaturna(Linnaeus,1758)causedby
countered a nymph sucking on a male butterfly Picromerusbidens.
thatwaswornsoheavilythatitwasunabletofly. Themajorityofcheckerspotspeciesdevelop
onplantscontainingiridoidglycosidesor(asin
the case of E. aurinia that feeds on Succisa
4.Discussion
pratensis)secoiridoids,whichtheysequesterfor
their defence (Wahlberg 2001, Suomi et al.
Picromerusbidensisageneralisedpredatorofa 2003).AlthoughthedistastefullnessofE.aurinia
wide range of insects, including hymenopteran, wasnotyetconclusivelyassayed,supportivein-
coleopteranandlepidopteranlarvae(Larivière& dicesincluderelativelyslowflight,fakingdeath
Larochelle1989,Volkov&Tkacheva1997).For when handled, aposematically coloured last-
suchageneralist,larvaeofE.auriniarepresentan instar larvae and pupae, and larval gregarious-
236 Konvickaetal. (cid:127) ENTOMOL.FENNICAVol.16
ness. P. bidens seems to be able to overcome —Entomol.News100:133–146.
lepidopteran chemical defences (Sirepinska Naumann,C.M.,Tarmann,G.M.&Tremewan,W.G.
1999:TheWesternPalaearcticZygaenidae(Lepidop-
1998, Vrabec & Jindra 1998, Naumann et al.
tera).—ApolloBooks,Stenstrup.304pp.
1999,Stefanescu&Ribes2000,Dantart2003).It
Sirepinska,A.1998:TowardsanIntegratedManagement
would be fascinating to study whether this bug of Dendrolimus pini L. — In: McManus, M. L. &
andotherpredatorypentatomids(cf.Hamilton& Liebhold, A. M. (eds.), Population Dynamics, Im-
Heath1976)actuallypreferchemicallyprotected pacts,andIntegratedManagementofForestDefoliat-
ingInsects.ProceedingsofConferenceheldinBanska
Lepidoptera and employ their protective com-
Stiavnica,Slovakia,inAugust18–23,1996.Onlineat
poundsfortheirowndefence,similarlytosome
http://www.iufro.org/iufro/iufronet/d7/wu70307/bans
phytophagous Heteroptera that sequester plant ka/
toxins(Aldrichetal.1997,Tullbergetal.2000). Stefanescu,C.&Ribes,J.2000:Unalarvad’Iphiclides
podalirius(Lepidoptera:Papilionidae)depredadaper
Acknowledgements.WethankO.NedvedandL.Zahla- Picromerusbidens(Heteroptera:Pentatomidae,Aso-
vovaforusefulsuggestions,MatthewSweneyforcorrect- pinae).—Butll.Soc.Cat.Lep.86:33–35.
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