Bt rice evaluation and deployment strategies.

Bacillus thuringiensis (Bt), a gram positive soil bacteria was first identified and named by Japanese microbiologist Shigetane Ishiwata in 1901. During sporulation Bt produces proteinaceous parasporal crystal proteins called δ-endotoxins, or Cry proteins, which are insecticidal. Numerous Cry proteins have been isolated and characterized from different Bt strains with activity against insects, mites and nematodes. Sprayable formulations containing these Cry proteins as active ingredients have contributed significantly in the field of insect pest management. Since the first cloning of cry genes from Bt,1 scientists have successively demonstrated that plants could be genetically engineered to express these cry genes for the control of dreadful insect pests. Eventually, the first transgenic crop expressing Btcry1Ac gene in cotton was approved in 1996 for commercial cultivation in the USA to manage bollworms.