Mites on Zygoptera, with particular reference to Arrenurus species, selection sites and host preferences

2007·0.69 MB·English

by  Baker, R A

Odonatologica36(4):339-347 December I,2007
Mites on Zygoptera, withparticular
referencetoArrenurus species,
selectionsites andhostpreferences
R.A.Baker¹*,P.J.Mill and A. Zawa²l
1School ofBiologicalSciences,UniversityofLeeds. LeedsLS29JT, United Kingdom
2DepartmentofInvertebrateZoologyand Limnology,UniversityofSzczecin,
Waska 13,PO-71-415 Szczecin,Poland
[email protected]
ReceivedFebruary26, 2007/ReviewedandAcceptedApril4,2007
Larval mitesofseveralArrenurus spp.arefoundasparasites onZygoptera.Data
fromPoland onprevalence,loads,andhostspecificityarepresented.Thelarvalmites
areidentified and their site selection and host preferences recorded. 7 Zygoptera
spp. and 7spp. ofarrenurid mite have been studied. Particular attention hasbeen
paidtoCoenagrionpuellaanditsparasites.New hostrecords areincluded.
INTRODUCTION
Severalordersofaquaticinsects, whoseimageslivepermanently outofwater,
are parasitized by larval mites.They are foundmostfrequently on theimaginal
stagesofinsectsbuttheimmaturestages canalsobeinfested. As aresultof re-
centdescriptions, basedonlarvalmorphologies, itisnowpossible toidentify,with
somedegreeofcertainty, thelarvalparasitesofzygopterans. Therecent descrip-
tions of arrenuridlarvae (ZAWAL, 2006a,2006b,2006c, 2006d, 2007) makeit
possible notonlyto identify thespecies ofparasitic miteinvolvedbutalso to in-
vestigatetheirhostpreferencesandattachmentsites ondamselflies.Inthisstudy,
sevenArrenurusspecies havebeen foundon seven Zygoptera species. In thecase
of Coenagrion puella fourspecies of parasitic miteare recorded. Theselection
sites ontheirhosts havebeennoted.
Thelifecycleofwatermitesinvolvethefollowingstages:egg,larva, nymphand
adult.Betweenthelarvalandnymphalstagesandbetweenthenymphalandadult
*CorrespondingAuthor:[email protected]
340 R.A. Baker,P.J.Mill& A.Zawal
stages, thereare quiescent stages in which a transformationtakes place. These
arereferred to as resting stages- post larvalresting stage 1 (nymphochrysalis)
andpostlarvalresting stage2(imagochrysalis). Arrenuridlarvaeare true para-
sitesandexploit theirinsect hosts forbothfoodand dispersal. Inodonates, wa-
termitelarvaealso formaphoretic association withthelast instarlarvaof the
damselfly(ZAWAL, 2004a), andwhenthe host emergesthey leavetheexuviae
oftheirlarvalhost transferring to the newly emerged adultodonateto become
parasitic. Engorgement onthe hostmaytakeseveral daysandthelarvae canre-
mainontheirhosts for upto two weeks. ABRO(1990) notedthatinEnallagma
cyathigerum and Coenagrion hastulatumthegreatestnumberofmitesonanin-
dividualoccurredonits maidenflight,thenumberdecreasing through adultlife.
Furthermore, individualswithaheavy loadtendedto disappearwhenstillyoung,
oftenbeforetheirreproductive phase. Conversely, in Pyrrhosoma nymphula and
Lestes sponsathe numberofmitesstartedoffrelativelylow butincreasedonre-
peated visits to the water forreproduction, the loadthus increasing withadult
age.
Miteshavebeenknownto liveonthesurfaceofOdonatasincethe eighteenth
centuryatleast.DE GEER(1778) published adescription and drawingsofwhat
was referred to as Acarus libellulae. SMITH & OLIVER (1976) and SMITH
(1988)examinedandreviewed thehost-parasite interactionsand impact ofwa-
termiteson insects ingeneral andthe relationship between mitesandodonates
hasbeenreviewed morerecently by CORBET(1999).
Species of Arrenurus havepreviously been described by several authorson a
varietyofinsecthosts including thoseon damselflies(CASSAGNE-MEJEAN,
1966; DAVIDS, 1997; MITCHELL, 1959; MUNCHBERG, 1935, 1963 and
STECHMANN, 1977). Theyattachto the ventralsurfaceofthehost mainly in
theposterior partofthe thoraxbutare also foundonabdominalsegmentsand
along wingveins.DAVIDS(1997)reviewedtheliterature,basedonCASSAGNE-
-MEJEAN (1966), MUNCHBERG (1935, 1963) and STECHMANN (1977)
andrecorded theknown relationships betweenodonatesand watermitespecies
fromnorthernEurope. Helists the followingzygopteransparasitised by 18dif-
ferentspecies of larvalarrenurids:Lestesbarbarus, L. dryas, L. sponsa, Coena-
grionhastulatum, C. mercuriale, C.puella, C.pulchellum, C. scitulum, Enallagma
cyathigerum, Erythromma lindenii, E. najas, Ischnuraelegans, Pyrrhosoma nym-
phula, Platycnemis latipes andP.pennipes.
MATERIALAND METHODS
Collections ofadultodonates tookplaceinthe summermonths(Juneand July2005 and May-
August2006),usingboth pondand entomologicalnets, atsitesnearSzczecin, Poland.Several sites
havebeen used. OnepondatUroczysko and fourpondsatDolina 7Mlynow(the valleyofseven
mills)weresampled. Odonates werealsocollected atpeat bogsnearthevillagesofZaklodzie and
Sikorki but these yieldednolarvalmites.In2006,severalsitesnearSzczecin weresampledwhichin-
MitesonZygoptera 341
eludedapeatbog,aneutrophicpond,adystrophiclakeand aldercarr.
Infectedand uninfected damselflies werepreservedin 70%alcohol. Subsequently,samplesofat-
tached larvaewerecounted,removed and mountedin Hoyersmedium. Selection sitesandnumbers
werenoted.Care hadtobetakentoremoveall ofthelarvae,someofwhich layontopofeachother
andwould havebeenmissedin aninsitu count.
Sevenspecies ofZygopterahostshavebeen examinedforlarvalarrenurids.Theyare:Coenagrion
puellafemale andmale,Coenagrionpulchellummale,Erythrommanajasfemale,Ischnura elegansfe-
male, Lestes dryasfemaleand male,Lestes sponsafemale and maleand Pyrrhosomanymphulafe-
maleandmale. The identification ofArrenurusspecieswasbased onlarvalmorphologyandZAW-
AL (2006a,2006b,2006c,2006d,2007)has producedtaxonomic descriptionsfortheidentification
ofseveral larvalarrenurids.
RESULTS
HOSTSPECIFICITYANDNEW HOSTRECORDS
Seven Arrenurusspecies werefoundontheadults ofthesevenodonatespecies
examined(Tab. I).Of thelatterCoenagrion puellawasbyfarthemostnumerous.
For thefirst timeA. bicuspidator has been recordedonP. nymphula, A.cuspida-
toron C. puellaandE. najas, A. cuspidifer onL. dryasandA. tricuspidatoron L.
sponsa.
PREVALENCEANDINTENSITYOFINFESTATION
Atotalof591 specimens wereexaminedformites,madeupof 77%of C.puella
and23%theothersix species. Ofthetotal, 128werefoundtobeparasitised giving
anoverallprevalenceof21.7%; theprevalence forC.puellaalonewas23.8%and
afigureof 14.6%foralltaxaexcept C.puella.Themean densityin C.puella was
8.1 butwashigherforotherspecies(20.5). Themaximumnumberofmitesfound
TableI
Arrenurus larvaefound onzygopterans
ZZyyggoopptteerraa AArrrreennuurruuss
bbrruuzzeellllii bbiiccuussppiiddaattoorr ccuussppiiddaattoorr ccuussppiiddiiffeerr mmaaccuullaattoorrppaappiillllaattoorr ttrriiccuussppiiddaattoorr
CCooeennaaggrriioonnppuueellllaa I/ I/ I1 ._ // . _
CCooeennaaggrriioonn
ppuullcchheelllluumm - I1 -- I/ - -
EErryytthhrroommmmaannaajjaass -- - /1 -- -- - //
IIsscchhnnuurraaeelleeggaannss - I1 .- ..- I/
Lteesstteessddrryyaass - - I/ . I/ --
Lteesstteessssppoonnssaa -- - .- - - //
PPyyrrrrhhoossoommaa
nnyymmpphhuullaa I/ I/ .- .- ..- .-
342 R.A.Baker,P.J.Mill &A.Zawal
onanindividualdam- Table II
selfly was onafemale Numbers ofmitesand damselflies
E. najas (101), the
Alltaxaof Alltaxaexcept AllC.puella
next highest number damsels C.puella
being 82 on afemale
C.puella (Tab. II). Number of
A total of 1282 damselflies 591 137 454
Number ofdamsels
miteswere found.Of
with mites 128 20 108
these 62.5%were re- Number ofmites 1282 409 873
cordedon thethorax, Prevalence 21.7% 14.6% 23.8%
35.3% on the abdo- Intensity 0-101 0-101 0-82
menand2.25%inthe Mean Density 10.0 20.5 8.1
Abundance 2.2 3.0 1.9
intersegmental area
betweenthethoraxandtheabdomen.Of themitesrecorded onC.puella, 14.5%
were foundon theabdomen,82.3%on thethoraxand3.2%betweenthetwo. In
thecombinedfiguresfortheotherhostspecies, 79.7%werefoundontheabdomen
andonly20.3%onthethorax(Tab.III).Thosemitesrecordedfromtheabdomen
weremainly foundonsegments4to 7,althoughallabdominalsegmentsfrom1-
9 were usedas attachmentsites. On thethorax, mitesoccurred mostfrequently
betweenand behindlegs 2and3as wellas behindthe3rd pair of legs (Tab. III).
SPECIESOFMITEAND THEIRSELECTIONSITESON THE HOST
Samples ofthe larvalmiteswereremovedandidentified, atotalof412in all
(Tab. IV). In addition38 otherswereeitheridentifiedto Anenurusspecies only
or theirsiteselectionwas notrecorded.Thepredominant species are A. cuspida-
tor(38%)andA. maculator(31 %)andthesetwo species together withA. tricus-
pidator (13 %)makeup82%ofallthelarvaefound.A.cuspidiferandA.papilla-
tor werebothrare butthatis mostlikely a reflectionofthescarcity oftheirhost
(Lestes dryas)in thesamples.
Almostall ofthe larvalmiteswere foundon the ventral sideofthemidand
posterior partsofthethoraxandoncertainsegmentsoftheabdomen(Tab. IV).
TableIII
Location oflarvalmites ondamselflies
TToottaallss BBeettwweeeenn//aatl BBee-- IInntteerrsseegg.. AAbbddoommiinnaallsseeggmmeenntt
bbaassee oofflleeggss hhiinndd tthhoorraaxx--
11//22 22//33 lleegg33 aabbdd i1 22 33 44 55 66 77 88 99
CC.ppuueellllaa 887733 1122 228888 441188 2288 4477 1100 1122 2244 1199 1144 1100 00
AAllll ttaaxxaaeexxcceepptt
CC.ppuueellllaa 440099 88 3333 4422 00 77 22 2244 5588 9911 7700 6677 66 I1
TToottaall mmiitteess 11228822 2200 332211 446600 2288 5544 1122 3366 8822 111100 8844 6688 66 11
Mites onZygoptera 343
TableIV
Watermite larvaeonparticularsegmentsofallZygoptera, basedonasampleof412ofthe 1282
mitesfoundin thissurvey
AArrrreennuurruuss BBeettwweeeenn//aatt BBeehhiinndd IInntteerrsseegg.. AAbbddoommiinnaall sseeggmmeenntt
bbaassee oofflleeggss lleegg33 tthhoorraaxx--
11//22 22//33 aabbdd.. 1122 33 44 55 66 77 TToottaall
bbiiccuussppiiddaattoorr 22 1122 55 44 - - - - - - - 2233
bbrruuzzeellllii 99 3300 1111 -- - - - - - - - 5500
ccuussppiiddaattoorr 33 6699 3388 -- - - - I1 1166 1144 1177 115588
ccuussppiiddiiffeerr -- - 11 -- .- ..- ..- ..- - - - 11
mmaaccuullaattoorr -- 99 8822 2211 1155 -- ------ - - - 112277
ppaappiillllaattoorr -- - 11 -- -- ----- --- - - -- 11
ttrriiccuussppiiddaattoorr 11 66 99 -- 33 99 66 77 66441 1 5522
TToottaall 1155 112266 114477 2255 1188 99 66 88 2222 1188 1188 441122
Note: Anuncertain A. clavigerspecimenhasalsobeen found
Mitelarvae havealsobeen noted,infrequently, on otherparts ofthe body such
as theprothorax, eye, headandneck buthave beenignored in thiswork. Only
threelarvalmitespecies, namely A.cuspidator, A.maculatorand A.tricuspidator,
were foundon theabdomen ofthedamselfliesandthese occur onthe anterior
andmiddlesegments.A. maculatorwas onlyfoundonthefirst segmentwhileA.
cuspidator was absent from thefirst three segments. All three species were also
foundonthethoraxand A.bicuspidator andA.maculatorwerefoundinthein-
tersegmental region betweenthethoraxandabdomen(Tab. IV).
Themostcommonly infectedzygopteranwas C.puella; atotalof454individu-
als havebeenexaminedformites, yielding 108infectedspecimens, withatotalof
872larvalmites(prevalence23.8%,intensity 0-82,meandensity8.1).Roughly one
thirdofthesemiteshavebeenidentifiedandtheirselectionsites noted.FourAr-
renurus species wererecorded from C.puellanamely A. bicuspidator, A. bruzelli
,
A. cuspidatorandA. maculator(Tab. V).
292 mite larvae have Table V
been identifiedto species Arrenurus speciesandnumber ofindividuals oninfected Coena-
from C. puella and they grionpuellafromparticularregionsofthebody,based onasam-
ple of292 ofthe 872mites foundinthissurvey
were mainly located on
the thorax(Tab. 111). An AArrrreennuurruuss BBeettwweeeenn//aatt BBeehhiinndd IInntteerrsseegg.. AAbbddoommeenn TToottaall
additional9 larvae were bbaasseeoofflleeggss lleeggss 33 tthhoorraaxx-- sseegg.. 11
identified to the genus 11//22 22//33 aabbdd..
only. A. cuspidator (36%)
bbiiccuussppiiddaattoorr -_1212 33 44 -- 1199
and A. maculator(45%) bbrruuzzeellllii 99 2299 - -- -- 3388
makeup 81 %ofall the ccuussppiiddaattoorr 22 6688 3355 -- -- 110055
larvae recorded on C. mmaaccuullaatloorr -- 99 110000 66 1155 113300
puella, the prevalence of TToottaall 1111 111188 113388 1100 1155 229922
344 R.A,Baker,P.J. Mill&A.Zawal
theotherspecies being A. bruzelli(13 %)andA. bicuspidator (7 %). A. cuspida-
toroccurs mainly between, and atthebaseof, legs 2and3and behindthethird
pair oflegs, whereas A. maculatoris foundalmost exclusively behind thethird
pair of legs andwas theonly species foundonthe abdomenof C. puella. Both
A. bicuspidator andA. maculatorweretheonlytwo thatoccurred intheinterseg-
mentalregion betweenthethoraxandabdomen.
DISCUSSION
Several Arrenurus species have larvaethatparasitize damselflies; in thisstudy
mostcommonly A. maculatorand A. cuspidator, although fiveotherspecies of
Arrenurushavebeenrecorded.ANDERSON(2002),workingonalargemuseum
collectionofodonatesinMinnesota, USA,foundthatover95%ofthemitelar-
vaewere Arrenurus spp.,although aspecies of Limnochareswas also recorded.
Zygoptera host lists forthevarious species ofArrenurushavebeendrawnup by
CASSAGNE-MEJEAN (1966)and DAVIDS(1997). Severalnewhosts records
arereported inthe presentpaperbutotherEuropean workers, including CAS-
SAGNE-MEJEAN (1966)andDAVIDS (1997), haverecordedlarval species of
Arrenurusondamselfliesthathavenotbeenfoundduring thepresentwork. With
furthercollectingand recording, moreinfected damselfly species andotherspe-
ciesof Arrenuruswill undoubtedly befound. DAVIDS(1997) lists 18parasitic
larvalmitesof this genusbut whetherall of theseare valid species is currently
underreview, especially since someofthem dateback to work published some
70 yearsago.CASSAGNE-MEJEAN (1966) lists ninespecies, including A. tri-
cuspidator, A. bruzelliand A. maculator.
Arrenuruslarvaeshow aclumped distributionon theirhosts, as demonstrat-
ed by several workers including ANDRES & CORDERO (1998) and ROLFF
(2000). ANDRES& CORDERO(1998) foundthat, inthecaseofthedamselfly
Ceriagrion tenellum,mitesaggregated strongly ontheirhost and98%ofimma-
ture adultmalesandfemaleswere parasitized, afigure far higher thanrecorded
inthepresentstudy. Inthis, mitesshowedapreference fortheareas betweenand
behind the secondand thirdpairs oflegs and,when they occurred ontheabdo-
men,foranteriorandmiddlesegments.Theyappearto prefersiteswherethecu-
ticle is less sclerotised such as the intersegmental areas,where theirmouthparts
mightmoreeasily beinserted, as thepresentworkandHOFFMAN& ANDER-
SON(2001)indicate.HOFFMAN& ANDERSON (2001)examined2591 adult
Zygoptera madeupof35species fromamuseuminsect collectionandfoundan
infestationlevelin theCoenagrionidae of 16%,which agreesfairlyclosely with
the overall figure inthis study but, unlikehere, mites were most frequently at-
tachedto themidthoraxandtheseventhabdominalsegment. Inanotherstudy,
ZAWAL(2004b) foundtheprevalence in C. puellatobe54%, thelarvaeprefer-
ringthe mesothorax, the proximal part ofthemetathoraxandtheanterior seg-
MitesonZygoptera 345
mentsoftheabdomen.
ROLFF(2000),whoworkedon C. puellaparasitized byA. cuspidator froma
pond where itwas the only hostand on C. hastulatumwhichco-occurred in a
secondpond, foundthatprevalence was close to 100%and thatthemean daily
abundanceranged from 1 to 45 mitesper host. McKEE etal. (2003) recorded
upto62ArrenurusperinfectedhostinNewZealandbutmeanburdenswerenot
relatedto the sex or size of thehost. CASSAGNE-MEJEAN (1966) recorded
loads thatreached 150for A. cuspidifer onIschnura elegans. CORBET (1999),
referring to the parasitic larval stage,has statedthat, “mite loadsvarybetween
years,populations andindividualswithinapopulation”. Itisclearfromprevious
work thatthere are considerablevariationsin both prevalence and loads.Care
mustthereforebetakenin drawingconclusionsfromtheresultsofisolatedstud-
iesonsingle populations of damselfliesandtheirparasites.
Aswithotherparasiticinfections, manyhostswere foundwithoutmites, some
withjustafewparasitesandonly asmallnumberofdamselflieshadheavy loads.
Prevalence overallwas 21.7%. Resourcepartitioning can occur when different
hosts are usedbut, whenthesamehostis utilised, differentspeciesofmitemay
remainsegregated in differentways including theirdifferentsitesofattachment
onthehost(LANCIANI, 1970).Somemitesdetachedfrom theirhostsandwere
foundatthebottomoftubescontaining thepreservative, havingpresumably done
so during fixation. These have been discounted in the present figures because
frequently several damselflieswerefixedin onetubefromaparticular collecting
site.
There may be distinctattachmentsites on asingle host species as MITCH-
ELL(1968) showed inthecaseoftwoarrenuridspecies living onthesame spe-
cies of damselfly. Onewas foundon thehost mesothoraxand theotheron the
abdomen; thelatter,undercrowdedconditions,maymoveto moreanteriorsites
ontheabdomen.Although therewas nothing tosuggest such a cleardistinction
as MITCHELL(1968) found, the sites most commonly selected in the present
work werebetweenthesecondandthirdlegsandbehindthethirdlegs, andlarvae
foundontheabdomenwerefrequentlyfromtheintersegmental areasbetweenthe
thoraxandabdomenand theanteriorandmiddleabdominalsegmentsbutnot
theposterior onesTheonly species foundontheabdomenwereA. cuspidator, A.
maculatorandA. tricuspidatorwithA. maculatortheonly mite foundonthe ab-
domenof C.puella. Someofthespecies appearto havebroadselectionsites,for
example A.cuspidator andA.tricuspidatorhavebeenfoundonthethoraxaswell
as ontheabdomen, andA.bruzellihasawidedistributionon thethorax.BOT-
MAN etal. (2002) examinedsite selectionin two arrenuridspecies onIschnura
positaand foundspecies specific selection sites.A. majorattachedto thethorax
andabdominal segments one to three, whereasA. americanus attached to ab-
dominalsegmentsfiveto eight. SMITH (1988) statedthat,although mite larvae
havecharacteristic sites ontheirhosts, thesemightvary withthehostspecies.
346 R.A.Baker,P.J. Mill&A.Zawal
Withregard to C.puella, where fourArrenurusspecies havebeen found, the
distributionofA.maculatorisparticularly interesting. Itslarvaappearsto occur
mainly behindthethirdpairoflegs, butalsointheintersegmentalregionbetween
thoraxandabdomenandtheanteriorregion ofthe abdomen.A. cuspidator, on
theotherhand, occurs further forward onthe host’sbody, mainlybetweenand
atthe baseof legs twoand three, although italso occurs behindthe 3rd pair of
legs. Thismaybethe resultofcompetition foraselectionsiteandsimilartothat
recorded by BOTMAN etal. (2002). However,untilfurtherwork is carried out
ontheArrenurusspeciesandtheiridentificationanddistributiononthehost,no
firmconclusionscan be drawn.
ACKNOWLEDGEMENTS
The authors would like tothank PETEREVENNETTforhis interest andhelp. This projectis
partly supportedfinanciallybythe CommitteeforScientific Research (Poland)forthe years 2004-
-2007:grant No.2P04C10527.
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