RISK ASSESSMENT OF TRANSGENIC RICE AGAINST NON-TARGET SUCKING INSECTS PESTS AND THEIR PREDATORS

Transgenic crops were developed from soil dewelling bacteria which have specific actionagainst lepidopteran pests. The Bacillus thuringiensis (Bt) δ-endotoxin protein binds with brush border membrane vesicles of insect midgut and causes disruption of the gut cells resulting in the death of the insect. Transgenic rice was also developed to show resistance against certain lepidopteran pests such as stem borers and leaf folders. Transgenic rice was found to be successful showing resistance against target pests under laboratory and field conditions. However, like other transgenic crops, Bt rice before commercialization needs to be tested for non-target effects on insects and bio-control agents. Bt rice can affect the sucking insects and their predators and parasitoids. From different experimental observations it was found that Nilaparvata lugens and Stenchaetothrips biformis were having some impacts from Bt rice under laboratory and field conditions. For predators and parasitoids no impact was found under laboratory and field conditions. It was observed that at the insects, predators and parasitoids community levels were unaffected in Bt rice fields as compared to control. As a conclusion it can be ascertained that if insect pests are affected or suppressed by the Bt rice in the paddy fields in terms of population densities, it can be an integrated pest management strategy. Which can result in less number of insects in Bt paddy fields as compared to control ultimately resulting in less damage and suppressing the secondary pests insects pests population in the field. For predators and parasitoids no harmful effects were found because of Bt rice. However further research is needed to investigate the effects of Bt rice on non-target insects and predators at molecular, biochemical and physiological level.