Status of insect resistance to Bacillus thuringiensis, mechanism and management -A review

Bacillus thuringiensis, commonly known as Bt, a most promising alternative to synthetic insecticides, has been used as an effective bio-pesticide in agriculture since long time. Two insecticidal protein, Cyt (Cytolysins) and Cry (Crystal ä-endotoxin) are the toxic substances responsible for the death of an insect. The durability of this novel insect control technology is questioned as many cases of insect population developing resistance to Bt cry proteins were observed and various mechanisms for resistance to Bt cry proteins were reported. Management of resistance in insect to Bt includes refugia, gene pyramiding and novel toxins.