戈林泉 130Pesticide Biochemisty and Physiology.docx

戈林泉 130Pesticide Biochemisty and Physiology.docx

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戈林泉130PesticideBiochemistyandPhysiology

SubmittedtoSendcorrespondenceto:

PesticideBiochemistyandPhysiologyJin-CaiWu

SchoolofPlantProtection

YangzhouUniversity

Yangzhou225009,P.R.China

-0514-*******

-0514-*******

E-mail:

jc.wu@

Matingpaircombinationsofinsecticide-treatedmaleandfemaleNilaparvatalugensStål（Hemiptera:

Delphacidae）planthoppersinfluenceproteincontentinthemaleaccessoryglands（MAGs）andvitellincontentinbothfatbodiesandovariesofadultfemales.

Lin-QuanGe1,Li-PingWang1,Ke-FeiZhao1,Jin-CaiWu*1,Liu-JuanHuang1,ZhenMin1,JamesD.Barry2

1SchoolofPlantProtection,YangzhouUniversity,Yangzhou225009,China

2DuPontCropProtection,Stine-HaskellResearchCenter,Newark,DE

*Correspondingauthor:

jc.wu@

ABSTRACT

Thebrownplanthopper,Nilaparvatalugens（Stål）（Hemiptera:

Delphacidae）,isaninsectpestinwhichoffspringareproducedbythematingofadultmaleswithadultfemales.Thisspeciesisaclassiccaseinwhichpestresurgenceisinducedbyinsecticides.Inthepast,studiesofresurgencemechanismshavefocusedoninsecticide-inducedstimulationofreproductioninadultfemales.Todate,however,therolethatmalesplayintheresurgencemechanismsofN.lugenshasnotbeeninvestigated.Theaimofthepresentstudyistoexaminechangesinproteinlevelsinmaleaccessoryglands（MAGs）inducedbytheinsecticidestriazophosanddeltamethrinandtodeterminetheirrelationshipwithvitellincontentinthefatbodiesandovariesofadultfemalesinthecontextofmatingpairs.OurresultsshowthatproteincontentinMAGsissignificantlyaffectedbymalematingstatus,insecticide,andinsecticideconcentration.InsecticideapplicationinducedincreasedproteinlevelsinMAGs.AgreaterquantityofMAGproductswastransferredtofemalesviamating.Thus,proteinlevelsinMAGssignificantlydecreasedaftermating.Experimentalmatingsindicatethatvitellincontentinbothfatbodiesandovariesofadultfemalesinmatingpairsconsistingofatreatedmaleandanuntreatedfemale（♂t×♀ck）issignificantlygreaterthanthatoffemalesinpairsconsistingofanuntreatedmaleandanuntreatedfemale（♂ck×♀ck）.Undervariousconcentrationsofthetwoinsecticides,vitellinlevelsarehighestinmatingpairsconsistingofatreatedmaleandatreatedfemale（♂t×♀t）,followedbymatingpairsconsistingofanuntreatedmalewithatreatedfemale（♂ck×♀t）.Thesefindingsdemonstratethat1）insecticide-treatedmaleshaveaneffectonfemalereproductionviamating;2）thereproductiveeffectsofinsecticidesonmalescanbetransferredtofemalereproductionviamating;and3）thereproductiveeffectofinsecticidesisstrongestinmatingpairsinwhichboththemalesandfemalesaretreatedcomparedtopairsinwhichonlyoneindividualistreated.Thesefindingsprovidevaluableinformationabouttheroleofmalesinpesticide-inducedresurgenceofN.lugens.

Keywords:

Nilaparvatalugens,insecticides,matingfactor,transference,vitellin

1.Introduction

ThebrownplanthopperNilaparvatalugens（Stål）（Hemiptera:

Delphacidae）isaclassicalinsecticide-inducedresurgentpest[1-2].Amonginsecticides,pyrethroids（deltamethrin）andorganophosphates（triazophos,methamidophos,parathionanddiazinon）areknowntoinducepopulationresurgenceofthisspecies[3-6].Physiologicalmechanismsforthepesticide-inducedresurgenceofN.lugensinvolvestimulationoffecundity[4,6-8].Thus,insecticide-inducedstimulationoffecundityisoneofthemaincausesofN.lugensresurgence.However,studiesofinsecticide-inducedstimulationofpestfecundityhaveconcentratedonthereproductionofadultfemaleswhileignoringinsecticide-inducedreproductiveeffectsinadultmales.N.lugensreproducessexually;bothmalesandfemalesareinvolvedinmatingpairs.Therefore,wehypothesizethatinsecticide-inducedreproductiveeffectsinmalescanbetransferredtofemalesviamatingandthatthisprocessinfluencesfemalereproduction.However,thiseffectisnotwellunderstood.

Forinsectswithsexualmating,manystudieshaveexaminedtheeffectofmalematingfactors（accessoryglandproducts,AGPs）onfemalereproductiveperformance.MalestransfernotonlyspermbutalsoAGPs,whichmaybeexpensivetoproduce,andtheamountorqualityofthesesubstancesmaydecreasewithincreasingmalematingfrequency[9,10].AGPstransferredduringmatingareknowntoaffectseveralbehaviorsininsects,amongwhichreducedfemalereceptivityandincreasedovipositionarethemostcommon[11,12].InthevariablefieldcricketGrylluslineaticepsStål,femalelifespanisaugmentedbyAGPs[13].Maledietandlarvalhostinfluencethedurationofcopulation,butmaledietdoesnotinfluencefemalefecundity.However,matingorderandmalelarvaldietinfluencefemalefertilizationsuccess[14].Manystudiesofotherinsectshavealsodemonstratedthatmaleaccessoryglandpeptidesregulatereproductiveperformance.Forexample,theadultmaleaccessoryglandsofDrosophilamelanogasterMeigensynthesizeandsecreteapeptidethatrepressesfemalesexualreceptivityandstimulatesoviposition[15].MultiplematinginthefemalemothUtetheisaornatrix（L.）increasesfecunditybutdoesnotincreaselongevityoreggmass[16].Layetal.（2004）[17]havefoundagreaterroleofmaleLocustamigratoria（L.）inreproduction,withpeptidesfromwhitesecretionsofthemaleaccessoryglands（MAGs）foundindevelopingeggs.Inaddition,thefecundityofadultfemaleSpodopteralituraF.increaseswhenfemalesmatewithmalemothswithhighqualitysperm[18].Moreinterestingly,Pszczolkowskietal.（2006）[19]havefoundthatinHeliothisvirescens（F.）,juvenilehormone（JH）storedintheMAGsistransferredtofemalesviamatingandthatthisprocesspromotesJHsynthesisandeggdevelopmentinmatedfemales.However,theeffectofinsecticidesonadultmalereproductionandthetransferenceofthiseffecttothereproductiveperformanceofadultfemalesviamatinghavenotbeenstudiedtodate.

Thepresentstudyisdesignedtoexaminetheeffectsofsublethaldosesoftwocommoninsecticides,deltamethrinandtriazophos,thatstimulatethefecundityofN.lugensonproteincontentinMAGsandonvitellogenininfatbodiesandvitellininovariesofadultfemaleN.lugens.Weutilizecontrolledmatingsbetweeninsecticide-treatedmalesandfemalesandcontrolmalesandcontrolfemales.Ouraimistounderstandtheeffectofinsecticide-treatedmalesonthereproductiveperformanceoffemalesviathematingprocess.

2.Materialsandmethods

2.1Ricevariety

Rice（OryzasativaL.）varietyHuaiDao13（japonicarice）wasusedintrials.ThisvarietyofricewasselectedbecauseitiscommonlyplantedinJiangsuprovince,China.Seedsweresownoutdoorsinastandardrice-growingsoilincementtanks（height60cm,width100cm,andlength200cm）.Whenseedlingsreachedthesix-leafstage,theyweretransplantedinto16-cmdiameterplasticpotswithfourhillsperpotandthreeplantsperhill.Riceplantsusedinexperimentshadreachedthetilleringstage.

2.2Insects

AlaboratorystrainofN.lugensthatwasoriginallyobtainedfromtheChinaNationalRiceResearchInstitute（CNRRI;Hangzhou,China）wasrearedinagreenhouseatanecologicallaboratoryatYangzhouUniversity.

2.3Insecticides

Twoinsecticideswereusedintrials:

thepyrethroid2.5%deltamethrinEC（YangnonChemicalCo.Ltd.,Yangzhou,Jiangsu,China）andtheorganophosphate20%triazophosEC（ChangqinPesticideCo.Ltd.,Jiangdu,Jiangsu,China）.\

2.3Experimentsdesign

Fourconcentrationsofeachinsecticide（1,3,6and12ppmofdeltamethrinand10,20,40and80ppmoftriazophos）wereselectedbasedonpreviousresultsfromasublethaltest[6,20].Eightythird-instarnymphswerereleasedperhill.Riceplantsatthetilleringstageweresprayed24hafterinsectswerereleasedusingaJactosprayer（MaquinasAgricolasJactoS.A.,Brazil）equippedwithaconenozzle（1-mmdiameterorifice,pressure45psi,flowrate300ml/min）.Controlplantsatthesamestageweresprayedwithamixtureofemulsifiersandtapwatersimilartothecompositionoftheinsecticidesbutlackingtheiractivecomponents.Eachtreatmentwasreplicatedthreetimes.Thetreatedandcontrolplantswerecoveredwithcages（screensize:

80-mesh）.Whenthenymphsreachedthefifth（final）_instar）,nymphsontreatedandcontrolplantswerecollectedandasinglenymphfromeachplantwasplacedinsideaglassjar（diameter10cm,height12cm）withuntreatedriceplants（26±2°Cand16L:

8D）.

Malesandfemaleswereseparatedone,two,andthreedaysafteradultemergence,with20malesand20femalesperreplicateusedseparatelytomeasureproteincontentinthemaleaccessoryglands（MAGs）andvitellincontentinthefatbodiesandovariesofadultfemales.Toexaminetheeffectofmatingpairsconsistingoftreatedoruntreatedmalesandfemalesonvitellincontentinthefatbodiesandovariesoffemales,fourmatingcombinationsweredesigned:

1）treatedmales（♂t）×treatedfemales（♀t）,2）♂t×untreatedfemales（♀ck）,3）untreatedmales（♂ck）×♀t,and4）♂ck×♀ck.Foreachofthesecombinations,wemadethreereplicatesof20malesand20femaleseach.Vitellincontentinthefatbodiesandovariesoffemaleswasdeterminedpriortoandaftermating.

2.4ExtractionofproteinfromMAGs

ProteinfromMAGswasextractedusingthemethodsofChenetal.（1988）[15]andSmidetal.（1997）[21].IndividualadultmalesofN.lugensweredissectedunderazoom-stereomicroscope（modelXTL20,BeijingTechInstrumentCo.,Ltd.,Beijing,China）inacooledpetridish.MAGswereremovedandplacedinseparate,pre-weighed