ABSTRACT
INTRODUCTION The vocal concerns of the public at the extensive employment of chemical pesticides for global crop protection has intensified efforts to evolve strategies that reduce the damage to crop plants and also ensure protection to human health. Bacillus thuringiensis (Bt) gene products are an important element of such an alternative approach. Bt is a gram positive, spore-forming bacterium that produces parasporal insecticidal crystal proteins (ICP), encoded by cry genes, that have specific toxicity towards several insect orders while being harmless to non-target species (Schnepf et al., 1998). Delivery of Bt gene products to plants basically involves three broad strategies: (a) the Bt gene product ICP is administered to the plant in the form of foliar sprays (Gaertner et al., 1993; Chet et al., 1993); (b) the Bt gene is cloned into the plant genome to impart genetic resistance against insect damage (Estruch et al., 1997); (c) micro-organisms are involved in the delivery of Bt gene products to crop plants (Dimock et al., 1989; Kim, 1993; Turner et al., 1993).
