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Effectiveness of transgenic cottons with Bacillus thuringiensis (Bt) cry1Ac gene along with non-transgenic commercial cultivars of Gossypium hirsutum and G. arboreum for the management of cotton bollworm, Helicoverpa armigera was evaluated at the research farm, International Crops Research Institute for the Semi-Arid Tropics, Patancheru, Andhra Pradesh, India. In general, there were no significant differences in oviposition between the transgenic and the non-transgenic cultivars under protected and unprotected conditions. The larval numbers were significantly lower on the transgenic hybrids during the 2004 rainy season under high infestation, but the differences in larval density between the transgenic and non-transgenic hybrids during 2002 and 2003 seasons under low levels of infestation were quite small. Bollworm damage in squares and bolls was significantly lower in the transgenic hybrids than in the nontransgenic ones, although there were a few exceptions. Differences in seed cotton yield between the transgenic and the non-transgenic hybrids were not significant under unprotected conditions at moderate levels of infestation during the 2002 and 2003 cropping seasons (except in the case of Mech 184). However, significant differences in seed cotton yield were observed during the 2004 cropping season under heavy bollworm infestation. Seed cotton yield of the first picking in transgenic hybrids was significantly greater than that of the non-transgenic counterparts. Transgenic hybrids suffered low shoot damage by spotted bollworm, Earias vittella. However, there were no differences between the transgenic and non-transgenic hybrids in their relative susceptibility to cotton jassid, Amrasca biguttula biguttula and serpentine leaf miner, Liriomyza trifolii, white fly, Bemisia tabaci, green bug, Nezara viridula, ash weevil, Myllocerus undecimpustulatus, and red cotton bug, Dysdercus koenigii. With a few exceptions, the bollworm damage and seed cotton yield of the G. arboreum varieties Aravinda and MDL 2450, and the G. hirsutum variety L 604 was not significantly different than that of the transgenic hybrids, and these varieties were also resistant to cotton jassid. The results suggested that it would be useful to combine transgenic resistance to H. armigera with plant characteristics conferring resistance to the target or non-target insect pests in the region in order to realize the full potential of transgenic plants for sustainable crop production. (c) 2005 Elsevier Ltd. All rights reserved.