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Indian Bt gene monoculture, potential time bombIncreasing reliance on a single gene in growing a variety of crops to make them resistant to bollworms could be dangerous, warn experts. Resistance is looming large among Bt crops in India.In March, this year (2005), an unprecedented number of hybrids of Bacillus thuringiensis (Bt)-resistant cotton will be planted in India. A recent model simulating the development of insect resistance to Bt cotton predicts that such monoculture could lead to resistance within a few years.
Long-term ecological effects of transgenic Bacillus thuringiensis (Bt) crops on nontarget pests have received limited attention, more so in diverse small holder–based cropping systems of the developing world. Field trials conducted over 10 years in northern China show that mirid bugs (Heteroptera: Miridae) have progressively increased population sizes and acquired pest status in cotton and multiple other crops, in association with a regional increase in Bt cotton adoption. More specifically, our analyses show that Bt cotton has become a source of mirid bugs and that their population increases are related to drops in insecticide use in this crop. Hence, alterations of pest management regimes in Bt cotton could be responsible for the appearance and subsequent spread of nontarget pests at an agro-landscape level.