U.S.EPA to propose limits on rootworm resistant corn hybrids

U.S. regulators for the first time are proposing limits on the planting of some genetically engineered corn to combat a voracious pest that has evolved to resist the bug-killing crops, a potential blow to makers of biotech seeds.

The measures proposed by the Environmental Protection Agency(EPA) represent a bold step to thwart the corn rootworm, a bug that ranks among the most expensive crop threats to U.S. corn farmers.

The plan is aimed at widely grown corn varieties sold by Monsanto Co., the first to sell rootworm-resistant corn, and rival seed makers including DuPont Co. and Dow Chemical Co.

Such corn seeds have been genetically modified to secrete proteins that are toxic to destructive insects, but safe for human consumption, helping to reduce farmers' reliance on synthetic pesticides.