VIGreenPreventionandControlofArmyworm

CaoJian(I)OccurrenceandhazardArmyworms,commonlyknownascolorfulwormsandmarchingworms,belongtotheNoctuidaefamilyofLepidoptera.TheyarepolyphagouspeststhatpreferPoaceaeplants.Intheyearoflargeoccurrence,theywillbringhugelossestoagriculturalproduction.Therefore,theyarelistedasmajorcroppestsinChina.VIGreenPreventionandControlofArmyworm(II)MorphologicalRecognition1.ImagoYellowishbrown,thebodycolorofmalemothsisdarkerthanthatoffemalemoths.Thecompoundeyesarereddish-brown,andtheantennaearefilamentous.Thereare2nearlyroundpaleyellowspotsneartheanteriormargininthecenteroftheforewings,and1smallwhitedotbelowthelateralroundspots.VIGreenPreventionandControlofArmyworm2.EggTheeggsofarmywormsaresteamedbun-shaped,slightlyglossy,about0.5mmindiameter,usuallyarrangedinstripsorblocksinasinglelayer;whentheyarefirstlaid,theyarewhite,graduallyturnyellowtobrown,andturnblackwhentheyarehatched.VIGreenPreventionandControlofArmyworm3.LarvaThereare6instarsintotal,thematurelarvaeareabout38mmlong.Thebodycolorvariesgreatly.Theheadisyellowish-brown,withbrownish-black"reversedeight"linesalongthemetamorphosisline.VIGreenPreventionandControlofArmyworm3.LarvaTherearefiveblackandwhitelongitudinallinesonthebodysurface,ofwhichthemidlineofthebackisthinandwhite,withthinblacklinesonbothsides.Thefourlongitudinallinessymmetricallydistributedonbothsidesofthebodyarewide.Therearedarkbrownspotsontheoutersideofthebaseofgastropods.VIGreenPreventionandControlofArmyworm4.PupaThepupais20mmlong,reddish-brown,andglossory.Therearehorseshoe-shapedindentationsonthe5thto7thsegmentsoftheabdominaldorsalsurfaceneartheanteriormargin.Therearethreepairsoftailspines,onepairinthemiddleislargeandstraight,andthetwosidesaretinyandcurved.VIGreenPreventionandControlofArmyworm(III)OccurrenceRegularity1.Lifehistoryofarmyworm(1)StagesIttakes40-50daystocompleteagenerationofarmywormVIGreenPreventionandControlofArmyworm1.Lifehistoryofarmyworm(2)Generations2–8generationsoccurinChina,and5–6generationsoccurinSichuanandChongqinginayear.VIGreenPreventionandControlofArmyworm2.Livinghabitsofarmyworm(1)LarvalhabitsThelarvaepreferawarmandhumidenvironment.Themostsuitabletemperatureforgrowthanddevelopmentis15–25°C,andtherelativehumidityis85%.PhotophobiaThanatosisOvereatingVIGreenPreventionandControlofArmyworm(2)PupationhabitsThelarvaepupateinasoilchamber1-3cmbelowthetopsoilneartheplant.Theoptimaltemperatureforpupaldevelopmentis15–20°C,andthesoilhumidityis10–15%,whichismostconducivetopupaldevelopment.VIGreenPreventionandControlofArmyworm(3)ImagohabitsSupplementnutritionPrefersweetandsourPhototaxisMigrationVIGreenPreventionandControlofArmywormIV.ControltechnologyArmywormshavethehabitoflong-distancemigration,andoccurrenceareasaresourcesofeachother.Itisnecessarytopayattentiontounderstandingthedynamicsofbothexternalandlocalsources.Whenconditionsaremet,mothtrapscanbeusedtolureimagoesandusegraingrasstolureimagoestolayeggs,andtheoccurrenceamountcanbepredictedaccordingtothenumberofluredimagoesandeggmasses.Iftherearealargenumberoflarvaeinthefield,decisivemeasuresshallbetakenintimetoeliminatethelarvaebeforethe3rdinstar.Thenumberofpestsourcesisthemainbasisforthelargeoccurrenceofarmyworm.Predictionmethod:①Usearmywormtrapstotrapimagoes,andmorethan300imagoestrappedin3daysindicatethepossibilityofthelargeoccurrence.Theformulaisliquor:water:brownsugar:vinegarintheratioof1:2:3:4(125gperpiece),andadd12.5gofcrystaltrichlorfon.Set2potsforeachplot,addhalfin3days,andreplaceinevery5days;checkthenumberofimagoestrapped.②Usethegraingrasstolureimagoestolayeggs.Takethreepiecesofgraingrassasabundle,put20bundlesineachplot,andreplaceevery3days;checktheeggmassandthenumberofeggs.VIGreenPreventionandControlofArmyworm(1)AgriculturalcontrolIftheoccurrenceofthefirstgenerationoflarvaeislarge,intheoccurrenceareasofthe2ndand3rdgenerationsofarmyworm,timelyploughing,harrowingandintertillageandweedingshallbecarriedoutincombinationwithsummerharvestandsummerplantingtoremoveweedsandreducethefoodsourcesofarmyworm.Besides,somelarvaewillbeturnedintothesoil,whichisnotconducivetothepupationoflarvaeandwilleliminatesomepupae.(2)Artificialcontrol①Manualeggcollectionandlarvaekillingcanreducethepopulationdensityinashorttime;grassbundlescanalsobeusedtotrapimagoestolayeggs.Beforethepeakperiodofoviposition,select10–20piecesofintactstraws,driedsorghumleaves,anddriedcornleavesandtiethemintobundlesandinserttheminthefield,500–800bundles/hm2,andreplacethemonceevery3days,whichcanreducethearmywormdensitybyabout50%.②Sugarbaitcanbeusedfortrappingandkillingduringthefullincidenceperiodofimagoes.FormulaI:sweetandsoursprinklingtrappingandkillingagent,i.e.liquor:water:brownsugar:vinegarintheratioof1:2:3:4(125gperpiece),add12.5gofcrystaltrichlorfon;formulaII:dis