Development and validation of integrated pest management strategies for Bt cotton under rainfed ecosystem

Abstract

Integrated pest management (IPM) module was developed and evaluated for transgenic Bt cotton during 2007–08 and 2008–09 at Dharwad and its performance was compared with the Bt grown under recommended plant protection and non -Bt with integrated pest management. In integrated pest management modules for both Bt as well as non-Bt cotton hybrids, included use of imidacloprid treated seeds, two sprays with imidacloprid (70 WS) and acetamiprid (20 SP) for sucking pest complex, trap cropping with okra, Abelmoschus esculentus (L.) Monech, spraying of 5% neem, Azardicta indica (L.) Juss seed kernel extract, detopping of shoot tip at 80 days after sowing, installation of pheromone traps and need-based application of insecticides for bollworm management. Recommended plant protection module for Bt involved only selective insecticides for sucking pests and bollworms. Results indicated low population of sucking pests in Bt integrated pest management, followed by non-Bt and Bt recommended plant protection. Bt integrated pest management registered 0.22 to 0.30 larvae of Helicoverpa armigera (Hubner)/plant compared to 0.32 and 0.29 larvae/ plant in recommended plant protection and 0.54 and 0.72 larvae/plant in non-Bt integrated pest management during 2007 and 2008, respectively. Fruiting body damage remained 3.24 and 3.57% in Bt integrated pest management as compared to 3.37 and 3.75% and 7.72 and 6.31% in Bt recommended plant protection and non-Bt integrated pest management, respectively. Similar trend of incidence was observed in case of pink bollworm across the genotypes and modules. Bt genotypes with integrated pest management resulted higher seed cotton yield of 3.13 and 2.59 tonnes/ha compared to 3.06 and 2.39 tonnes/ha in Bt recommended plant protection and 2.86 and 2.14 tonnes/ha in non-Bt with integrated pest management in 2007–08 and 2008–09, respectively. The net returns (` 69 970 and 61 350/ha) was more from Bt integrated pest management as compared to Bt recommended plant protection (` 67 676 and 55 403/ha) and non-Bt integrated pest management (` 61 155 and 43 633/ha) in both seasons.