Genetically modified corn, which produces anti-pest toxin, is no longer as efficient at killing the bugs. The resistance arose quickly, due to some extent, to farmers avoiding the simple, but profit-cutting precaution of crop rotation.

The problem that may soon render null the economic and environmental benefits of GM maize, which produces the so-called Bacillus thurinigiensis (Bt) toxin, was highlighted in a study published online in this week’s Proceedings of the National Academy of Sciences.