EFFICACY OF INSECTICIDES ON PESTS OF MULBERRY AND THEIR INFLUENCE ON THE BIOLOGY AND SILK YIELDS OF MULBERRY SILK WORM Bombyx mori L. (LEPIDOPTERA:BOMBYCIDAE)
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Date
1998
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Professor Jayashankar Telangana State Agricultural University
Abstract
ThepresentstudieswereundertakenatTirupati,during 1996-97tostudythefaunalcomposition
and seasonal incidence ofmulberrypests, in addition toevaluationoffewinsecticidesfor
theirefficacyagainstmulberrypestsandtoxicityagainstsilkwormlarvae.Theexperimentalmaterial comprisedofM-5cultivarofmulberry,raisedinagardenof25cents.
Theresultsrevealedinfestationofmulberrybynineinsectpests,belongingtosevenorders
and 12 families.Amongthese,peakinfestationofmites,thrips,aphidsandbugswasobservedduringsummermonths,whilethepeakpopulationofleaf hOppers,caterpillars andgrasshopperswasobservedduringthemonthofJanuary, whentheminimumtemperatureswerequitelow.However,maximumpopulationof mealybugswasobservedduringrainyseason. Studiesonrelativeefficacyoftheinsecticidesagainstmulberrypestswas undertaken in arandomizedblockdesign withthree replications and seven
treatments, including control.Resultsrevealedtheeffectiveness ofPhosalone (0.05%)andDimethioate(0.1%)againstthesuckingpests;andDDVP(0.05%)and Endosulfan(0.05%) againstthedefoliators. Nemazole(1%)was alsoobserved effectiveinthemanagementofbothsuckinganddefoliatorpestpopulationlevels. Studiesoninsecticidaltoxicitytosilkwormlarvaerevealedrelativelyshorterwaitingperiods for DDVP (0.05%) andNemazole(1%) and longperiods forcarbaryl(0.1%)andPhosalone(0.05%). Insecticidaltreatmentofmulberryleaveswasalso noticed to resultinincreased larval andpupal durations. Phosalone(0.05%) inspite of its high effectiveness against the insect pests is not recommendedforuseonmulberryduetohighresidualtoxicityandunfavourable effectsonthelarval,pupal,cocoonandshellweights,inadditiontosilkshellratio andlengthofreeledsilk. Carbaryl (0.1%)had also,ingeneralrecordedsimilar effects,whileDDVP (0.05%),Dimethioate(0.1%)andEndosulfan(0.05%)had mostlyrecordedeffectsonparwithcontrol.Incontrast,Nemazole(1%)recorded shorterwaitingperiod, satisfactory control ofdifferentmulberrypests and favourable effects on the economiccharacters ofsilkworm viz., cocoonweight, shellweight,andlengthandweightofreeledsilk.Itisthereforerecommendedfor extensiveuseinsericulture.
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D5721