nearly one-fifth of the farmers in the us midwest are ignoring federal rules about how much transgenic maize they should plant, indicates a recent study. Experts fear this non-compliance could encourage pests to develop resistance to the insecticide produced by the crop.

Some transgenic maize contains a gene from the bacterium Bacillus thuringiensis (bt), which allows the corn to produce a natural insecticide. Under rules laid down by the us Environmental Protection Agency (epa), farmers who plant bt maize must devote 20 per cent of their acreage to non-bt varieties. The