By using the techniques of biotechnology, insect resistant crops have been developed. Some strains of Bacillus thuringiensis (Bt) produce protein crystals which contain a toxic insecticidal protein that **** some insects like lepidopterans, coleopterans and dipterans, etc.
- Specific Bt toxin genes were isolated from Bacillus thuringiensis and cloned in bacteria.
- Specific Bt toxin genes obtained from Bacillus thuringiensis are used in several crop plants like cotton by providing them resistance from insects.
- Bt toxins are insect-group specific coded by a gene called cry which are of various types—proteins encoded by the genes cryIAc and cryIIAb control the cotton bollworms, that of cryIAb controls corn borer
