Precopulatory and tandem directional activity of Sympetrum sanguineum (Müller) males at the places of pairing (Anisoptera: Libellulidae)

5 Pages·1995·1.1 MB·English

by  Gorb, S N

Odonatologica24(3):341-345 September1,1995
SHORT COMMUNICATIONS
Precopulatoryandtandemdirectionalactivity
ofSympetrumsanguineum(Müller) males
at theplaces ofpairing
(Anisoptera: Libellulidae)
S.N. Gorb
DepartmentofInsect Physiology,
Schmalhausen InstituteofZoology,Ukrainian AcademyofSciences,
B.ChmelnickogoStr. 15,Kiev, UKR-252601, Ukraine
ReceivedSeptember18, 1994/ RevisedandAcceptedFebruary27, 1995
Intheexperimentswith female models 2 questions wereasked,viz. (1)How do
perchingmales, which are oriented in different directions relative to the bank,re-
spondtothefemales? (2)Whatistheflightdirectionchosenby amaleafterseizureof
the female? The majority ofperchingmales (46.5%)aredirected towards the bank.
Males facingtowards the bank orparalleltoitrespondedtothe female model more
oftenwithtandem reactionthan males facingaway fromthe bank.52% ofmalesflew
towardsthe bank afterseizure ofthe female model. Thus,males which perch facing
thewaterare most likely tofly towards it when in tandem. Nearly 8% ofthe males
whichcapturedfemale models(n=82)tried toovipositwiththemusuallyafterunsuc-
cessfulattemptsofthe male to mate.Theresults obtained suggest the leadingrole
playedby S.sanguineummales inovipositionbehaviour.
INTRODUCTION
Itis known that both sexes ofsome Odonata species can find potential larval
habitatsandrecognizeplaces ofoviposition (GIBBONS &PAIN, 1992;WILDER-
MUTH, 1992). Sympetrum species, whichmay mate farfromthepotential larval
habitats,havebeenobserved intandemsflying inthedirectionofwater bodiesand
then ovipositing there (MIYAKAWA, 1994;pers. observ.). These tandemsoften
cannot seethewater,but can findit. Itseems thatmales ofSympetrum areableto
findpotential habitatsforlarvaeandalsotheplacesforoviposition. MOORE(1952),
EDA(1976) andUTZERI(1989)suggestthatmales,whichcanmaketheoviposition
movements withdead females or withoutany female, are able to carry out ovi-
position behaviour.Itis hypothesized that thecomplex behaviourrelated to ovi-
342 S.N.Gorb
position (habitat search, choice ofoviposition place, oviposition movements) is
provided inSympetrum mainly by males.
Sympetrumsanguineum maleswait forfemalesonlow vegetationandrecognize
themagainst thesky, wheneverafemalefliesabovethemale.Thosemales which
occupy thelowestperches are mostactive. Malesperching attheplacesofpairing
faceindifferentdirections.Questions askedin thiscommunicationwere; (1) How
doperching males, whichareorientedto differentdirectionsrelativetothebankof
the water body, respond to females? (2) Whatis the flight directionchosen by a
maleafterseizureofthefemale?
METHODS
Field observations andexperimentswerecarried outin July-August, 1992,atmoistmeadows near
the Supoy Lake(Kievprov.,central Ukraine), ata distance of 10-30 m from the lake bank. Intact
ovipositingtandemswerephotographedusingaflash-unit.
Experimentswithmodelswerecarriedoutfrom 10.00to 15.00husingafishing-rod.Female mod-
els (dry specimens ofconspecificfemales)were shown to each male only oncein profile slightly
above themale. Five male responses wererecorded: (t)tandem: male seizes themodel with anal
appendages,(s)survey: male fliesaround themodel withoutattemptingtopair, (i)indifference:male
continues toperch,(e)escape:malerapidlyfliesaway,(a)attack:male suddenlyrushes atthemodel,
usuallyfrombottom.Fourdirectionsofaperchingmale’s body andamale’s flightafterseizure ofa
female weredefined:dl - towards thebankofthe lake (315°-45°),d2- totheright,paralleltothe
bank (45°-135°),d3- away fromthe bank (135°-225°),d4 - tothe left,parallelto the bank(225°-
-135°).The direction towhich amale had beenfollowed for morethan 3mjustafterseizure ofthe
female model wasregisteredasflightdirectionin theexperimentsin whichthedirection oftandem
flightwasrecorded. In all244responses wererecorded.
RESULTSAND DISCUSSION
BODYDIRECTIONOFTHEPERCHINGMALESANDTHEIRRESPONSES
TOFEMALEMODELS
The majorityoftheperching males(46,5%, n=230) were directedtowardsthe
bank (Fig. 1). Moreover, malesperching facing towardsthebankor parallel to it
responded to thefemalemodelmore often with a tandemformationthan males
directedaway fromthebank(dl - 49%, d2 - 37%, d4- 43%andd3 - 23%respec-
tively)(Figs 2-5). Ethograms obtainedforperching males,whichwere directedto
dl,d2andd4(dl-d2,x^lO.02,p=0.0401,df=4;dl-d4, x^.24,p=0.0727,df=2)
significantly differfrom ethograms obtained forperching malesdirectedto d3,
(dl-d3, x2=44.74, pcO.0001, df=3; d2-d3, x2=44.39, p<0.0001, df=3; d4-d3,
p=0.0001,df=2). Thusperching malesfacing towardsthebankrespond
moreoftenwithtandemreaction.Probably, thesemales havehigherlevel ofmoti-
vationforpairing.
Directional activityin Sympetrumsanguineummales 343
FLIGHTDIRECTIONOFTHEMALE AFTERSEIZUREOFAFEMALEMODEL
Only truetandemformationsweretakenintoaccount(n=82).52%ofmalesflew
towardsthebank(Fig. 6).Theflight directionsofS.sanguineum malesweresimi-
lartothemaleperching directions 1-52,p=0.0092, df=3).Thus,themalecan
leadthefemaletothedirectionofthewater.Themale’sorientationontheperchis
probably somekindofpreorientation beforethetandemflight.Thispreorientation
may help amaletofindthewaterduring tandemflightmore quickly.
OVIPOSITION
Intandemthemalefliesactively andthefemalemainly keeps her balance.This
Figs 1-5.Resultsobtained inexperimentswithmaleresponses tothefemalemodels. Charts areori-
entedaccording tothe directionofperchingmales,forwhich the chartwas obtained; (1)percentage
ofperchingmales directedtodifferent directions;- (2)tothe bank;- (3)alongthebank totheright;
—(4)fromthe bank;—(5)alongthe banktotheleft.- [n=numberofrecordings].
344 S.N.Gorb
suggests the leading role ofthe S.
sanguineum malesinhabitatsearch,
oviposition site choiceandoviposi-
tionmovement generation.However,
tactile communicationbetween the
sexes exists in dragonfly tandems
(UTZERI, 1989).Probably thiscom-
municationis controlledby the ar-
rester system (GORB, 1989; 1993)
which is “on” in the female during
tandemcontact withthemale(GORB,
1991)andcanregisterheaddisplace-
ments relative to the neck postcer-
vical sclerites withtheaidofhairand
campaniform sensillaatthepointsof
contact.
Nearly 8% of males which cap-
tured femalemodels(n=82) triedto
oviposit with the female model Fig.6.FlightdirectionofS.sanguineummales after
seizureoffemale. Percentageof82recordingsisgiven
(“oviposition”withadeadfemalehas
accordingtotheflightdirection.
previouslybeenreported byMOORE
(1952), EDA (1976) and UTZERI
(1989)), butsuch behaviourwas observed usually after unsuccessful attempts by
the maleto stimulatethe femaletomate. Thus, in nature males may sometimes
guard andoviposit with females whichhave refusedcopulations. Probably, after
oviposition the male may repeat his attempts to mate. Therefore, oviposition in
tandemwithafemalewithwhichthemalehasnot previously matedcangivetothe
maleachanceto mate withthe femaleafteroviposition.
ACKNOWLEDGEMENTS
Mysincere thanksaredue toMrs E.GORBforherassistance in the field and tothe anonymous
reviewer for valuablecriticism andlanguageimprovement.
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