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)

RAJENDRA PRASAD, P.RAMAIAH, MANIYARAM2018-06-112018-06-111998D5721http://krishikosh.egranth.ac.in/handle/1/5810050853ThepresentstudieswereundertakenatTirupati,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.ennullEFFICACY OF INSECTICIDES ON PESTS OF MULBERRY AND THEIR INFLUENCE ON THE BIOLOGY AND SILK YIELDS OF MULBERRY SILK WORM Bombyx mori L. (LEPIDOPTERA:BOMBYCIDAE)Thesis