Frequency of resistance alleles to Cry1Ac toxin from cotton bollworm, Helicoverpa armigera (Hübner) collected from Bt-cotton growing areas of Telangana state of India.

Transgenic cotton expressing Bacillus thuringiensis (Bt) cry1Ac and cry2Ab toxin genes is widely cultivated to manage bollworm complex in India. Cotton bollworm Helicoverpa armigera (Hübner) is one of the most serious of this complex. It is likely to evolve resistance to Cry toxins in view of continual selection pressure due to extensive cultivation of Bt cotton.