Utilization of Bt Cotton hybrids in integrated pest management and their impact on non target insects

Abstract

The investigations were carried out on the farmers field at Hadagali taluk of Bellary newline(district) and Department of Agricultural Entomology, University of Agricultural Sciences, newlineDharwad during 2003-04 and 2004-05 crop seasons. newlinePopulation of Helicoverpa armigera (Hubner) larvae was significantly lowest on Bt newlinecotton (0.09 0.14 larvae/plant) compared to non-Bt (0.39 0.41 larvae/plant) and newlineconventional cotton hybrids (0.28 0.40 larvae/plant). Population of sucking pests viz., newlineleafhoppers, aphids, whiteflies and thrips, natural enemies viz., Chrysoperla, coccinellids and newlinespiders, soil micro-arthropods and macro-organisms showed no significant differences in time newlineand magnitude of appearance between Bt, non-Bt and conventional cotton hybrids. While, the newlinepopulation of red cotton bug was significantly high on Bt cotton compared to non-Bt cotton newlineand conventional cotton hybrids. newlineOvipositional preferences of H. armigera and Chrysoperla carnea (Stephans) did not newlinediffer between Bt cotton or non-Bt cotton versions of the same hybrid. But, differential newlineovipositional preference was evident across the different cotton hybrids. So, among the cotton newlinehybrids, RCH-2Bt which preferred less by H. armigera and more by C. carnea for oviposition newlinecan be a best option for natural enhancement of C. carnea. newlineTritrophic interaction studies between Bt cotton, H. armigera and larval parasitoid, newlineCampoletis chlorideae (Uchida) indicated significant negative impact of Bt cotton hybrids on newlineC. chlorideae parasitization at flowering stage, but not at boll maturation stage of the crop. newlineAmong the different Bt cotton hybrids evaluated, MECH-184Bt, RCH-144Bt, RCH- newline20Bt and RCH-2Bt performed superior by recording lower population of H. armigera, newlinePectinophora gossypiella (Saunders) larvae and fruiting bodies damage and inturn recoded newlinehigher seed cotton yield (11.08, 10.33, 9.37 and 9.14 q/ha, respectively) followed by MECH- newline162Bt and MECH-12Bt under un-protected conditions. However, with respect to sucking newlinepests, MECH-184Bt and RCH-2Bt were superior. newlineAmo