Response of field populations of helicoverpa armigera hubner to bt cotton cry1ac and its management

Abstract

Studies on response of Helicoverpa armigera collected from different cotton growing newlineareas of Karnataka to Cry1Ac, synchrony in H. armigera adult emergence from Bt cotton and newlineother alternate hosts, estimation of crop yield gain in Bt cotton against bollworms, validation of newlineintegrated resistance management (IRM) strategy to Bt cotton and exploitation of Bt cotton as newlinea trap crop in conventional cotton pest management were carried out at RARS, Raichur. newlineThe maximum LC50 of 0.028 and#956;g/ml of diet was recorded in Raichur population. In late newlineseason, higher LC50 values of 0.037 and 0.026 and#956;g/ml of diet were recorded in Dharwad and newlineRaichur populations, respectively. But there was no significant difference among six different newlinepopulations of H. armigera response to Cry1Ac toxin. newlineThe total number of H. armigera moths emerged from Bt and non Bt cotton were 6.60 newlineper cent and 42.80 per cent, respectively and total per cent emergence of H. armigera moths newlinefrom red gram was maximum (95.60%). In late season, moths emerged from Bt cotton were newlinevery less (10.80%). On cultivated Bt cotton, larval survivability was from zero to 0.16 larvae newlineper plant as compared to 0.00 to 1.56 larvae/plant in non Bt cotton. newlineReaction of different Bt cotton hybrids against bollworms indicated that RCH-144Bt newlinerecorded maximum GOB per plant (59.17/plant) which was on par with RCH-371Bt newline(55.71/plant) and RCH-2Bt (54.67/plant). Significantly highest seed cotton yield of 19.60q/ha newlinewas recorded in RCH-144Bt. newlineBt IRM recorded significantly superior seed cotton (38.73 q/ha) yield compared to Bt newlinefarmers practice (35.92 q/ha). The net profit per ha was maximum in Bt IRM module (Rs. newline68392/ha) as compared to Bt farmers practice (Rs. 59875/ha). newlineCotton IPM plot and Bt border trap crop treatment recorded maximum good opened newlinebolls (41.93 and 42.11/plant) with least bad opened bolls (9.17 and 10.22/plant). These two newlinetreatments also excelled and registered higher seed cotton yield of 20.60 and 20.60 q/ha newlinerespectively.