Monsanto, which is based in a St. Louis, developed the corn to produce its own insecticide to fend off rootworm, a pest whose larvae feed off the plant's roots. The plant's pesticide is derived from a protein contained in a natural soil bacterium called Bt, or Bacillus thuringiensis.
"This new variety of corn pest control holds great promise for reducing reliance on conventional insecticides now used on millions of acres of corn in the U.S.," Stephen L. Johnson, an assistant administrator at the EPA, said as the agency approved the corn Tuesday.
Farmers have had to depend on chemical insecticides and alternating soybean and corn crops every other year to control rootworm.
Monsanto officials said the government's approval came just in time for the 2003 planting season. The variety will be sold as YieldGard Rootworm corn.
"The registration of YieldGard Rootworm corn is great news for the hundreds of seed companies and tens of thousands of U.S. farmers who are seeing the benefits of biotech products," said Jennifer Ozimkiewicz, a Monsanto spokeswoman.
EPA officials said they want to reduce the risk of rootworm developing a tolerance to the corn's pesticide by requiring Monsanto to ensure that 20 percent of the acreage where the seeds are planted is kept as a buffer zone.
The zone would be a refuge for rootworms that won't be in contact with the pesticide. EPA officials expect the unexposed rootworms to mate with those exposed to the Bt bacterium, which should prevent the insects from passing on their tolerance and help the pesticide remain effective.
Gregory Jaffe, biotech director at the Center for Science in the Public Interest, warned that setting aside 20 percent of the acreage to prevent resistance development isn't enough. He said at least half the acreage should be set aside for the buffer zone as an extra precaution.