Stridulatory Sound-Production and Its Function in Females of the Cicada Subpsaltria yangi

13 Pages·2015·2.4 MB·English

RESEARCHARTICLE
Stridulatory Sound-Production and Its
Function in Females of the Cicada
Subpsaltria yangi
ChangqingLuo,CongWei*
KeyLaboratoryofPlantProtectionResourcesandPestManagement,MinistryofEducation,Entomological
Museum,NorthwestA&FUniversity,Yangling,Shaanxi,712100,China
* [email protected]
Abstract
Acousticbehaviorplaysacrucialroleinmanyaspectsofcicadabiology,suchasreproduc-
tionandintrasexualcompetition.Althoughfemalesoundproductionhasbeenreportedin
somecicadaspecies,acousticbehavioroffemalecicadashasreceivedlittleattention.Inci-
OPENACCESS cadaSubpsaltriayangi,thefemalespossessapairofunusuallywell-developedstridulatory
organs.Here,soundproductionanditsfunctioninfemalesofthisremarkablecicadaspe-
Citation:LuoC,WeiC(2015)StridulatorySound-
cieswereinvestigated.Werevealedthatthefemalescouldproducesoundsbystridulatory
ProductionandItsFunctioninFemalesoftheCicada
Subpsaltriayangi.PLoSONE10(2):e0118667. mechanismduringpairformation,andthesoundswereabletoelicitbothacousticandpho-
doi:10.1371/journal.pone.0118667 notacticresponsesfrommales.Inaddition,theforewingswouldstrikethebodyduringper-
AcademicEditor:AlexCórdoba-Aguilar, formingstridulatorysound-producingmovements,whichgeneratedimpactsounds.
UniversidadNacionalAutonomadeMexico,MEXICO Acousticplaybackexperimentsindicatedthattheimpactsoundsplayednoroleinthebe-
Received:October17,2014 havioralcontextofpairformation.Thisstudyprovidesthefirstexperimentalevidencethat
femalesofacicadaspeciescangeneratesoundsbystridulatorymechanism.Weanticipate
Accepted:January22,2015
thatourresultswillpromoteacousticstudiesonfemalesofothercicadaspecieswhichalso
Published:February24,2015
possessstridulatorysystem.
Copyright:©2015Luo,Wei.Thisisanopenaccess
articledistributedunderthetermsoftheCreative
CommonsAttributionLicense,whichpermits
unrestricteduse,distribution,andreproductioninany
medium,providedtheoriginalauthorandsourceare
credited. Introduction
DataAvailabilityStatement:Allrelevantdataare Acousticsignalingisawidespreadformofcommunicationandoccursnotonlyinvertebrates,
withinthepaperanditsSupportingInformationfiles. butalsoinarthropodsandeveninplants[1–4].Amonganimals,acousticcommunicationis
Funding:Thisresearchwaspartiallyfundedbythe usedindifferentbehavioralcontexts,suchasintra-sexualcompetition,inter-sexualinterac-
NationalNaturalScienceFoundationofChina(Grant tions,andterritorialdefense[2,5,6].Forexample,sound-basedcommunicationplaysavital
No.31170360,No.31093430,No.31493021)andthe
roleinreproductioninadiverserangeoftaxa(e.g.,frogsandinsects),inwhichacousticadver-
FundamentalResearchFundsfortheCentral
tisementisgenerallythedomainofmales[2,6].Thenumberandkindofcommunicativesig-
UniversitiesofChina(QN2011053)toCW.The
nalsintherepertoireofananimalspeciesdependonthecomplexityofitslifeactivities[7].
fundershadnoroleinstudydesign,datacollection
andanalysis,decisiontopublish,orpreparationof Differentacousticpropertiesofcommunicationsignalspotentiallyencodedifferentkindsofbi-
themanuscript. ologicallysignificantinformationsuchassex,dominancestatusandphysicalcondition[8].
Sound-producingbehaviorhasevolvedindiversearachnidandinsectgroups.Manyspeciesof
CompetingInterests:Theauthorshavedeclared
thatnocompetinginterestsexist. spiderscanproducesoundsbystridulatorymechanism,and12differenttypesofstridulatory
PLOSONE|DOI:10.1371/journal.pone.0118667 February24,2015 1/13
FemaleAcousticBehaviorofaCicadaSpecies
apparatusareknowninspiders[9–11].Acousticsignalsofspidersareusedininter-sexual
communication,intra-sexualagonisticinteractions,ortoreinforceotherdefensivesignals
showedtowardspotentialpredators[12–14].IntheInsecta,sound-producingstructuresmay
involvealmostanypartoftheinsect’sexoskeleton[15],andthemainsound-producingmecha-
nismsarevibration,percussion,stridulation,clickingmechanism,andairexpulsion[16,17].
Amonginsects,cicadasarewell-knownfortheirtymbalsound-producingmechanismin
males[18].Thetymbalorganisessentiallycomposedofaribbedmembraneatthebaseofthe
abdomenandanattachedmuscle,andsoundsaregeneratedwhenthetymbalmuscleactivity
deformsthestiffmembrane[19–21].Malecicadasemitdifferenttypesofacousticsignalsin
differentbehavioralcontextsinordertogainbenefitssuchasattractingconspecificfemales
anddeterringpredators[18,22–25].
Soundproductionisgenerallythoughttoberestrictedtomalecicadas,andmostprevious
studieshavefocusedonacousticbehaviorofthemales.However,insomecicadaspecies,fe-
malesareabletogeneratesounds,functioninginintersexualcommunication,bymeansof
wing-flicking[26–30].Femalesinthesecicadasusuallydonothaveanyspecializedsound-pro-
ducingstructuresexceptthatinsomespeciestheforewingcostaisdistinctlyangled[31,32].
WhatisinterestingandunusualisthatfemalesofthecicadaSubpsaltriayangiChenpossess
apairofstridulatoryorgans[33].Thestridulatoryorganisafileandscrapersystemsimilarto
thatfoundincrickets,katydidsandgrasshoppers[32–34].S.yangiisamedium-sizedcicada
withadultbodylengthof28.0–33.2mm,andistheonlyknowncicadaspeciesofthesubfamily
TettigadinaeinChina[33,35].Inthepresentstudy,weconductedscraper-ablationexperi-
mentstoillustratehowfemalesofS.yangiproducesounds.Furthermore,acousticplaybackex-
perimentswerecarriedouttoexplorehowmalesrespondtosoundsproducedbyS.yangi
females,andhowdifferentcomponentsofthefemalesoundsfunctioninthebehavioralcontext
ofpairformation.
MaterialsandMethods
EthicsStatement
Nospecificpermitswererequiredforthisstudy.Thisstudydidnotinvolveendangeredorpro-
tectedspecies,andthecicadaSubpsaltriayangiusedinthepresentstudywasnotincludedin
the“ListofProtectedAnimalsinChina”.
Studysiteandspecies
0 0
Thestudysite,Chunshugouvalley(38°33.699N,105°55.217E)wherethecicadaSubpsaltria
yangiisparticularlyabundant(Fig.1),islocatedintheHelanshanNationalNatureReserve,
NingxiaHuiNationalityAutonomousRegion,China.Thiscicadapopulationoccursateleva-
tionsbetween1400mand1600m.Investigationswereperformedbetween6and26June2014.
AdultsofthiscicadaspeciesfeedmainlyonEphedralepidosperma(Ephedraceae),amedicinal
plantusedintraditionalChinesemedicine.Voucherspecimensaredepositedinthescientific
collectionoftheEntomologicalMuseum,NorthwestA&FUniversity(NWAFU),China.
Morphologyofthestridulatoryorgan
WeexaminedthemorphologyofthescraperandthefileusinganOlympusSZX10stereomi-
croscope(OlympusCorporation,Tokyo,Japan).Thenumberofridgesofthefilewascounted.
MicrographswerecapturedwithaRetiga2000Rdigitalcamera(QImaging,Canada)mounted
onaNikonSMZ1500stereoscopiczoommicroscope(NikonCorporation,Tokyo,Japan),and
then80sequentialshotsatdifferentfocaldepthswereprocessedusingtheAuto-MontagePro
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FemaleAcousticBehaviorofaCicadaSpecies
Fig1.AfemaleofSubpsaltriayangi.Scalebar,1cm.
doi:10.1371/journal.pone.0118667.g001
softwaretogenerateasinglecompositeimage.Themorphologyofthefileandthescraperwere
alsoexaminedusingascanningelectronmicroscope(S-3400N,Hitachi,Tokyo,Japan).
Soundrecordingandanalysis
ThesoundsproducedbyS.yangifemaleswererecordedusingalinearPCMrecorderwithste-
reomicrophones(PCM-D50,Sony,China;frequencyrange20–20000Hzanda44.1kHz/16
bitsamplingresolution).ThesoundswererecordedinWAVfileformat,andthesoundsre-
cordedontheleftchanneloftherecorderwereusedforacousticanalysis.Acousticanalysis
wasconductedusingtheRavenPro1.4(TheCornellLabofOrnithology,Ithaca,NY,USA)
andtheSeewavepackage[36],acustom-madelibraryoftheRsoftwareplatform[37].
Scraper-ablationexperiments
FemalesofS.yangiproducedsoundsinresponsetoacousticallyadvertisingmales.Behavioral
observationsonthesound-producingbehaviorofS.yangifemalesindicatedthatsoundswereemit-
tedduringtherapidupwardanddownwardmovementsoftheforewings(S1Video).Theforewing
movementsmightcauseinteractionbetweenthescraperandthefile(Fig.2A),sothesoundswere
probablygeneratedbythestridulatorymechanism.However,similartothesound-producing
mechanismofthewing-bangercicadaPlatypediaputnami,thesoundsmightbeproducedbybang-
ingthetegminaagainstthebody[34].Therefore,itisdifficulttoexplicitlydeterminetheunderlying
Fig2.Scraper-ablationexperiment.(a)Theredarrowindicatesoneofthepairedstridulatoryorgansofa
female.(b)Theredarrowindicatesthatthescraperofthestridulatoryorganwasremoved.
doi:10.1371/journal.pone.0118667.g002
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FemaleAcousticBehaviorofaCicadaSpecies
mechanismofsoundproductioninS.yangifemales.Todeterminetheroleofthestridulatoryor-
gansinsoundproduction,weconductedscraper-ablationexperimentsinwhichsoundsrecorded
fromfemaleswithandwithoutstridulatoryscraperswereanalyzedandcompared.
Thecapturedfemaleswerekeptontheirhostplantscoveredwithgauzenettinguntiltesting.
Scraper-ablationexperimentswereconductedonlywithmatureandunmatedfemales,because
ourpreviousfieldworkhaddemonstratedthatonlyunmatedmaturefemalesofthisspecies
wereacousticallyrespondingtoadvertisingmales,whichisthesametoperiodicalcicadas[28].
Thecapturedfemalesweretestedindividually.Afemalewasplacedinasmallcage
(0.25×0.25×0.50m),inwhichtheinsectbehavednormallyaccordingtobehavioralobserva-
tions.Thesoundsemittedbythecagedfemalewererecorded.Thepairedscrapersofthefemale
werethencarefullyremovedwithsurgicalscissors(Fig.2A,B).Whenthefemaleperformed
normalsound-producingmovements(i.e.,upwardanddownwardmovementsofthefore-
wings),thesoundsemittedbythefemalewererecordedsecondtime.
Atotalof15femaleswereusedinscraper-ablationexperiments.Allexperimentswerecar-
riedoutbetween9:00amand3:00pm,aperiodcorrespondingtothepeaksingingactivityof
thiscicada.Duringtheexperiments,theambienttemperaturerangedfrom29to34°C.
Maleresponsestofemalesounds
BehavioralobservationssuggestedthatthesoundsproducedbyS.yangifemalesfunctionedin
thebehavioralcontextofpairformation.TodeterminewhetherthesoundsproducedbySub-
psaltriafemaleselicitacousticandphonotacticresponsesfromconspecificmales,wecon-
ductedacousticplaybackexperimentsinthefield.
Ahigh-qualitysoundrecording(i.e.,havinghighamplituderelativetobackgroundnoiseand
nooverlapwithothersounds)fromafemaleofS.yangiwasselectedforplaybackexperiments.
PlaybackswereconductedusingaSonyPCM-D50LinearPCMRecorderandaMogicQ2loud-
speaker(frequencyresponse,150–20000Hz).Adigitalsoundlevelmeter(BenetechGM1357;
fastresponse,Aweighting)wasusedtomeasuresoundpressurelevels.Thepeakoutputintensity
oftheloudspeakerwasadjustedto60dBSPLmeasuredat50cmfromtheloudspeaker.ThisSPL
iswithintherangeofnaturalvariationrecordedinthecicadapopulation(range,55.4–65.8dB
SPL;mean±SD=60.5±3.2dBSPL;N=19).Weperformedexperimentsbetween9:00amand
3:00pm.VegetationinthedryhabitatoccupiedbyS.yangiconsistsprimarilyofdrought-tolerant
dwarfshrubsandherbaceousplants,generallynotexceedingonemeterinheight.
Wetestedwhetherthefemalesoundselicitphonotacticresponsesfromconspecificmalesin
thefield.Atotalof25maleswereusedforthisexperiment.Weplacedtheloudspeakeronthe
groundandabout3mfromanacousticallyadvertisingmale.Then,theacousticstimuluswas
presentedfromtheloudspeaker.Therepetitionrateofthesoundswas82soundsperminute.
Duringtheplaybackperiod,aphonotacticresponsewasnotedifthemaleflyingtowardsand
landingwithin50cmoftheloudspeaker.A‘noresponse’wasnotedifthemaleflyingawayor
remainingstillafter3minoftheplayback.
Wetestedwhetherthefemalesoundselicitacousticresponsesfromconspecificmalesinthe
field.Atotalof35maleswereusedforthisexperiment.Asinglemalewasplacedinacage
(0.25×0.25×0.50m).Theloudspeakerwasplacedapproximately1mfromthemale.Therewas
a3-mincontrolperiodinwhichnosoundwaspresented,followedbya3-mintestperiodin
whichtheacousticstimuluswasemittedbytheloudspeaker.Thesoundpressurelevelatthe
positionofthetestedmalewasabout55dBSPL.Duringthecontrolandtestperiods,were-
cordedwhetherthemaleproducesoundsinresponsetotheplayback.Theplaybackexperi-
mentswereconductedfarawayfromthestudiedcicadapopulationtoavoidthepossible
influenceofthesoundsproducedbyothermalesandfemalesinthenaturalpopulation.
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FemaleAcousticBehaviorofaCicadaSpecies
Behavioralimportanceofdifferentcomponentsoffemalesounds
Acousticplaybackexperimentsdemonstratedthatfemalesoundscouldstimulateacousticand
phonotacticresponsesfrommales(seeMaleresponsestofemalesoundsinResults).Acoustic
analysisrevealedthateachfemalesoundcouldbedividedintothreecomponents:A,B,andC.
BothcomponentAandBwereproducedbystridulatoryorgans,whereascomponentCre-
sultedfromtheimpactbetweentheforewingsandthebody(seeScraper-ablationexperiments
inResults).Toexplorewhetheronlyonecomponent,orthecombinationoftwocomponents
orallthethreecomponentsplayaroleinelicitingmaleresponses,furtherplaybackexperi-
mentswerecarriedouttoinvestigatetheefficiencyofvariousacousticstimuliineliciting
acousticandphonotacticresponsesfrommales.Wecreatedseventypesofplaybackstimuli:A,
B,C,AB,AC,BC,andABC.StimulusABCwasanaturalrecordingofoneS.yangifemale
(Fig.3A,B;S1Audio).StimuliA,B,C,AB,AC,andBCweremodifiedfromstimulusABC.Sti-
muliA,BandCwerecreated,respectively,byreplacingthecomponentBandC,componentA
andC,andcomponentAandBfoundineachfemalesoundofthestimulusABCwithsilence
(Fig.3C–E;S2–S4Audios).StimuliAB,ACandBCwerecreated,respectively,byreplacingthe
componentC,componentB,andcomponentAfoundineachfemalesoundofthestimulus
ABCwithsilence(Fig.3F–H;S5–S7Audios).Theseacousticstimuliweregeneratedatasample
rateof44.1kHzand16-bitresolutionwiththeRpackageSeewave.Theplaybackmethodsused
weresimilartothatdescribedabove(i.e.,Maleresponsestofemalesounds).
Statisticalanalysis
StatisticalanalysiswasundertakenwithSPSS17.0software.Dataarepresentedasmeans±S.
D.Allstatisticaltestsweretwo-tailed,andP<0.05wasconsideredsignificant.
Fig3.Acousticplaybackstimuli.(a)OscillogramofapartofstimulusABC.(b)Detailedoscillogramofa
femalesoundmarkedbytheboxina.(c,d,ande)Detailedoscillogramsofamodifiedfemalesoundincluded
instimulusA,B,andC,respectively.(f,g,andh)Detailedoscillogramsofamodifiedfemalesoundincluded
instimulusAB,AC,andBC,respectively.
doi:10.1371/journal.pone.0118667.g003
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FemaleAcousticBehaviorofaCicadaSpecies
Fig4.Thepairedstridulatoryorgansofafemale.(a)Afile(redarrow)issituatedattheleftanterior
angleofthemesonotum.(b)Afile(redarrow)issituatedattherightanteriorangleofthemesonotum.(c)A
micrographofastridulatoryfile.(d)Theredarrowindicatesthescraperofastridulatoryorgan.(e)Ascanning
electronmicrographshowingtheridgesofafile.(f)Ascanningelectronmicrographshowingthescraperofa
stridulatoryorgan.
doi:10.1371/journal.pone.0118667.g004
Results
Morphologyofthestridulatoryorgan
Subpsaltriayangifemaleshaveastridulatoryorganoneachsideofthebody.Theleftandright
stridulatoryorgansaresimilarinmorphology.Thestridulatoryfileisaconspicuousovalarea
ontheanteriorangleofthemesonotum(Fig.4A,B).Thefileisyellowishincolour,andbearsa
seriesofridges(Fig.4C).Theridgesarehighlysclerotizedandalmostparalleltoeachother
(Fig.4C,E).Therewasnosignificantdifferencebetweenthenumberofridgesonleftandright
files(left:17.50±2.76;right:17.90±2.13;pairedt-test,P>0.05,N=20).Thebaseoftheinner
marginoftheforewing,servingasthescraper,isthickened,sclerotizedandslightlycurvedout-
wards(Fig.4D,F).
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FemaleAcousticBehaviorofaCicadaSpecies
Fig5.Comparisonofsoundsrecordedfromthefemalesbeforeandafterablationofthestridulatory
scrapers.(a)Oscillogramoffoursoundsproducedbyapre-ablatedfemale.(b)Detailedoscillogramofa
singlesoundproducedbyapre-ablatedfemale.(c)Oscillogramoffoursoundsproducedbyapost-ablated
female.(d)Detailedoscillogramofasinglesoundproducedbyapost-ablatedfemale.
doi:10.1371/journal.pone.0118667.g005
Scraper-ablationexperiments
InS.yangifemales,soundproductionwascorrelatedwiththefastforewingmovements(S1
Video).Atypicalfemalesoundhadacomplexandstereotypedstructure,andcouldbedivided
intothreecomponents:A,B,andC(Fig.5A,B;S8Audio).Afterablationofthescrapersonthe
forewings,thefemalecicadascouldnormallyperformthesound-producingmovements(i.e.,
upwardanddownwardmovementsoftheforewings).However,thesoundproducedbypost-
ablatedfemalesdidnotshowathree-componentstructure,andconsistedofonlycomponentC
(Fig.5C,D).Withoutscrapers,thefemaleslosttheirabilitytoproducecomponentsAandB.
TheseresultsdemonstratedthatcomponentsAandBfoundinfemalesoundswereproduced
bythestridulatorymechanism.Anupwardmovementoftheforewingsledtoafile-scraperin-
teraction,producingthecomponentA.Thedownwardmovementoftheforewingsresultedin
asimilarfile-scraperinteraction,andthecomponentBwasgenerated.Animpactbetweenthe
forewingsandthebodyoccurredwhentheforewingsmoveddowntotheirrestingposition.
Thisimpactinducedtheproductionoftheimpactsound,i.e.,componentC.
Maleresponsestofemalesounds
PlaybackexperimentstocallingmalesinthefieldshowedthatmalesofS.yangidisplayeda
strongphonotacticresponsetoconspecificfemalesounds.Allmales(N=25)usedintheexper-
imentsflewtowardstheloudspeaker,fromwhichthefemalesoundswerebroadcasted.The
maleslandedneartheloudspeaker,andsomeofthemultimatelymadephysicalcontactwith
theloudspeaker.Anotherfindingwasthatthefemalesoundswereabletoevokeacousticre-
sponsesfromallmalestested(N=35).
Behavioralimportanceofdifferentcomponentsoffemalesounds
Inadifferentsetofplaybackexperiments,stimulusABC(viz.naturalfemalesounds)evoked
highlevelsofbehavioralresponsesfrommales.Thirty-threeof35(94%)malesshowedphono-
tacticresponsestostimulusABC(Fig.6A),andthisstimulusevokedacousticresponsesfrom
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FemaleAcousticBehaviorofaCicadaSpecies
Fig6.Efficiencyofthesevenacousticstimuliinelicitingbehavioralresponsesfrommales.(a)Males’
phonotacticresponsestodifferenttypesofacousticstimuli.Differentlettersindicateasignificantdifference
(P<0.05).(b)Males’acousticresponsestodifferenttypesofacousticstimuli.Differentlettersindicatea
significantdifference(P<0.05).
doi:10.1371/journal.pone.0118667.g006
34of35(97%)males(Fig.6B).Incontrast,stimulusCwasunabletoelicitacousticandphono-
tacticresponsesfrommales(Fig.6A,B).BothstimuliAandBcouldevokeacousticandphono-
tacticresponsesfrommales,buttheyweresignificantlylesseffectivethanstimulusABC
(Fisher’sexacttest,P<0.05inallcases;Fig.6A,B).Similarly,stimuliACandBCtriggeredsig-
nificantlyweakerbehavioralresponsesfrommalesthanstimulusABC(Fisher’sexacttest,P<
0.05inallcases;Fig.6A,B).StimulusABwasaseffectiveasstimulusABCinelicitingmalere-
sponses(Fisher’sexacttest,P>0.05inallcases;Fig.6A,B).Altogether,theseresultssuggest
thatbothcomponentAandcomponentBproducedbythestridulatoryorgansareessentialto
effectivelyelicitmalephonotacticandacousticresponses,whereascomponentCisneithernec-
essarynorsufficienttoevokebehavioralresponsesfrommales.
Discussion
Ininsects,stridulatorymechanismisanextremelywidespreadsound-producingmethod,and
suchmechanismhasbeendescribedinatleastsevendifferentinsectorders[17,38].
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FemaleAcousticBehaviorofaCicadaSpecies
StridulatorystructuresandmechanismsareparticularlywellunderstoodinOrthoptera[39–
41].Incicadas,themainmethodofsoundproductionisthetymbalmechanism,andthetym-
balsystemisonlydevelopedinmales,exceptthatintwospeciesfromthefamilyTettigarctidae,
TettigarctacrinitaandT.tomentosa,bothsexespossessrudimentarytymbalswithreducedap-
parenttymbalmuscles[42,43].Asinmostothercicadaspecies,thefemalesofSubpsaltria
yangilacktymbalorgans,buttheyhaveevolvedwell-developedstridulatorystructures.Inthe
presentstudy,weexploredthepossibilityofstridulatorysoundproductionbyS.yangifemales.
WeshowedthatfemalesofS.yangiwerecapableofproducingsoundswiththeirstridulatory
organs.Thisis,toourknowledge,thefirstexperimentaldemonstrationthatfemalesofacicada
speciescanemitsoundsbystridulatorymechanism.Ourstudyaddstoincreasingevidencethat
specializedsound-producingorgansandacousticsignalingarenotrestrictedtomales
ofcicadas.
Thefunctionsoffemalesoundshavebeenstudiedinmanyanimaltaxa.Inbirds,soundsare
usedbyfemalestoattractmates[44–46],todefendterritories[47–49],toensuremaleparental
care[50],andtomaintainintrapaircontactandcoordinatebreedingactivities[51–54].Previ-
ousstudieshaveshownthatfemaleanuransproducesoundstoincitemale-malecompetition
[55,56],tostimulatemalevocalization[57,58],andtoattractmales[59,60].Inspiders,females
ofsomespeciesproducestridulatorysoundsignalstoinducechangesinmalegenitalicmove-
mentsduringcopulation[13],andtoinformmalesofsexualreceptivity[14].Insomeinsects,
femalesoundproductionplaysaroleincourtshipcommunication[61–64]andindeterring
predators[65].Inthisstudy,weinvestigatedthefunctionalsignificanceoffemalesoundpro-
ductioninthecicadaSubpsaltriayangi.Thefemalesoundsareproducedinresponsetocalling
songsofmales.Ouracousticplaybackexperimentsclearlydemonstratethatthesoundsemitted
byS.yangifemalescanelicitacousticandphonotacticresponsesfromconspecificmales.The
soundsproducedbythefemalesofthiscicadaspeciesoperateasintraspecificcommunicative
signals,andfunctioninthebehavioralcontextofpairformation.Thecommunicationsystem
ofS.yangi,characterisedbymaleadvertisementandfemaleacousticresponse,issimilartothat
oftheperiodicalcicadasMagicicadaspp.[28]andtheAustraliantick-tockcicadaCicadetta
quadricincta[27].
Scraper-ablationexperimentsandacousticanalysisinourstudyrevealthatthefemale
soundsofS.yangiconsistofstridulationsproducedbystridulatorymechanismandimpact
soundsresultedfromimpactbetweenforewingsandbody.Inthewing-bangercicadaPlatype-
diaputnamiDavis,femalescanalsoproduceimpactsoundsbyslappingtheforewingsagainst
thebody,andtheimpactsoundsareusedbymalesforspeciesrecognitionduringpairforma-
tion[34].However,ouracousticplaybackexperimentsindicatethattheimpactsoundspro-
ducedbyfemalesofS.yangidonotplayaroleinpairformation,andthestridulationsalone
aresufficienttoelicitsexualresponsesfrommales.Wesuggestthattheimpactsoundsarejust
afunctionlessby-productwhenthefemaleS.yangiusestridulatorysystemtoproducesounds.
ThemalesofS.yangirelyprimarilyonthefemales’acousticresponsestorecognizeandfind
thefemales.Femalesoundsofthisspeciesmightbeonlyproducedinresponsetothemalecall-
ingsongsduringpairformation,becauseourfieldobservationshowedmatedfemalesstopped
emittingsoundstorespondtoadvertisingmales.Thisobservationsuggeststhat,similartofe-
malesofperiodicalcicadas[28],femalesofS.yangimaymateonlyonceormatedfemalesare
likelytobesexuallyunreceptive.Moreover,thereissofarnoclearbehavioralevidencetoshow
thatthefemalesproducesoundsinanyotherbehavioralcontext.However,givenourlimited
fieldobservations,wecannotruleoutthepossibilitythatsoundproductionmightbeusedby
thefemalesinothercontexts,e.g.,female-femaleinteractions.Furtherdetailedbehavioral
studyisneededtotestthispossibility.
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InadditiontofemalesofS.yangi,femalesofsomeothercicadaspeciesalsopossessstridula-
toryorgans[30,66].Forexample,a‘tegmen-wing’typeofstridulatoryorganwasdescribedby
Boulard[67]forcicadasinthegenusMaroboduusDistant.Inthesespecies,thethirdanalvein
ofthetegmen,coveredwithmanyspines,formsthescraper,andabout50conicalteethjustbe-
hindtheanteriormarginofthecostaofthehindwingconstitutethefile.Recently,Moulds[32]
describedastridulatorysystemfortheAustraliangenusCyclochilaAmyot&Serville.This
stridulatorysystemconsistsofafileontheundersideofthelateralangleofthepronotalcollar
andascraperonthebaseoftheforewing.Unfortunately,thesound-productionandassociated
behaviorsinfemalesoftheseremarkablecicadaspecieshavenotyetbeenproperlyinvestigated.
Informationyieldedfromacousticstudiesonthesecicadafemalesisofgreatimportancefora
betterunderstandingoftheevolutionoffemaleacousticbehaviorincicadas.
SupportingInformation
S1Audio.ThestimulusABCusedinacousticplaybackexperiments.Thisacousticstimulus
wascreateddigitallyatasamplerateof44.1kHzand16bitsresolution.
(WAV)
S2Audio.ThestimulusAusedinacousticplaybackexperiments.Thisacousticstimulus
wascreateddigitallyatasamplerateof44.1kHzand16bitsresolution.
(WAV)
S3Audio.ThestimulusBusedinacousticplaybackexperiments.Thisacousticstimuluswas
createddigitallyatasamplerateof44.1kHzand16bitsresolution.
(WAV)
S4Audio.ThestimulusCusedinacousticplaybackexperiments.Thisacousticstimuluswas
createddigitallyatasamplerateof44.1kHzand16bitsresolution.
(WAV)
S5Audio.ThestimulusABusedinacousticplaybackexperiments.Thisacousticstimulus
wascreateddigitallyatasamplerateof44.1kHzand16bitsresolution.
(WAV)
S6Audio.ThestimulusACusedinacousticplaybackexperiments.Thisacousticstimulus
wascreateddigitallyatasamplerateof44.1kHzand16bitsresolution.
(WAV)
S7Audio.ThestimulusBCusedinacousticplaybackexperiments.Thisacousticstimulus
wascreateddigitallyatasamplerateof44.1kHzand16bitsresolution.
(WAV)
S8Audio.ThesoundsofaSubpsaltriayangifemale.Thesoundswererecordedatasample
rateof44.1kHzand16bitsresolution.
(WAV)
S1Video.AfemaleofSubpsaltriayangiemitssoundsinresponsetotheadvertisementsig-
nalsproducedbyamale.
(MP4)
Acknowledgments
Wethanktwoanonymousreviewersforcriticalrevisingthedraftofthismanuscriptandoffer-
ingvaluablecomments.
PLOSONE|DOI:10.1371/journal.pone.0118667 February24,2015 10/13