Q43. Bt cotton variety that was developed by the introduction of toxin gene of Bacillus thuringiensis (Bt) is resistant to
1. Insect pests
Some strains of Bacillus thuringiensis produce proteins that kill some insects like lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes).
B. thuringiensis forms protein crystals which contain a toxic insecticidal protein.
The toxin is coded by a gene called cry which is of various types. For example, proteins encoded by the genes cryIAc and cryIIAb control the cotton bollworms and that of cryIAb control corn borer.