Bioefficacy studies of biorational approaches against Leucinodes orbonalis Guenee on brinjal in Himachal Pradesh

Abstract

Studies were carried out to know the incidence of Leucinodes orbonalis on brinjal in agro-climatic newlinezone I and II of Himachal Pradesh and data on the incidence of L. orbonalis were recorded at monthly newlineinterval during 2019 and 2021. The crop was found to be infested with L. orbonalis at all the locations newlineduring both the years. Incidence of L. orbonalis appeared early in the month of May and remained up newlineto the end of the season. The peak incidence of L. orbonalis was recorded in the month of July and newlineAugust on shoots and fruits of brinjal during both the years. Among all the locations, Una district had newlinea maximum shoot and fruit infestation (25.33 and 28.83%, respectively) during 2019, while in 2021 newlinethe maximum shoot infestation was recorded in Hamirpur district (26.50%) and fruit infestation in newlineKangra district (28.64%). The intrinsic toxicity studies against neonate larvae of L. orbonalis revealed newlineemamectin benzoate as most toxic with LC50 value of 0.0043 ppm followed by spinosad (0.0303 newlineppm), Bacillus thuringiensis (3.989 ppm), azadirachtin (8.847 ppm), Brahmastra (24203.194 ppm) newlineand Agniastra (29795.95 ppm). The field experiments were undertaken during the kharif season of newline2020 and 2021 at the Experimental Farm of the Department of Entomology, CSK Himachal Pradesh newlineKrishi Vishvavidyalaya, Palampur. For the management of L. orbonalis, different approaches were newlineevaluated under three modules, cultural and mechanical methods (M1), natural products and biopesticides newline(M2) and insecticides (M3). In Module 1, amongst seven treatments, minimum mean shoot infestation newline(9.33%) and fruit infestation (number as well as weight basis i.e., 12.68 and 13.86%) was recorded in newlineneem cake (NC) + clipping of shoots. In Module 2, out of nine treatments, application of Bt resulted newlinein least mean shoot infestation (13.56%), whereas fruit infestation on the number basis was minimum newlinein neem cake + Azadirachtin; on the weight basis, neem cake + Bt recorded lowest per cent fruit newlineinfestation (15.27%). In case of Module 3, shoot in