EPA Restricts Planting of Biotech Corn

By Cat Lazaroff

WASHINGTON, DC, January 17, 2000 (ENS) - The U.S. Environmental Protection Agency (EPA) has announced unprecedented new restrictions on the planting of genetically modified corn. The measures are intended to reduce the risk that the modified crop could cause ecological disruptions, harm nontarget species like monarch butterflies, and lead to increased pesticide resistance in insects.

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Farmers will have to plant up to half their fields with conventional corn, if they want to plant Bt corn (Photo courtesy USDA)
The new EPA rules were detailed in letters to biotech seed producers sent last week by Janet Andersen, director of EPA's biopesticides and pollution prevention division.

Corn modified to produce the Bt toxin, which combats pests like European corn borers, has been criticized because of studies suggesting pollen from the biotech corn could kill harmless butterflies and moths. Bt corn uses a gene from the toxic soil bacterium Bacillus thurigiensis to produce a substance toxic to some insects. The same toxin is used in some conventional chemical pesticides. Some scientists warn that exposing insects to low levels of Bt toxin in corn pollen could lead to super-pests resistant to the toxin.

Effective immediately, farmers who wish to plant Bt corn must plant 20 percent to 50 percent of their acreage with conventional, unmodified corn. The conventional corn must be planted in structured refuges that could provide some protection for insects, the Environmental Protection Agency (EPA) says. In addition, farmers must undertake additional monitoring in their fields "as an early warning system to detect any potential resistance," according to the EPA.

In certain limited geographic areas, particularly where Bt corn could harm threatened or endangered butterflies, the EPA will order additional restrictions on sales and planting of the modified crop.

The new requirements could be costly for farmers, and may lead to a decline in orders for Bt corn seed. However, "the industry has agreed to the Agency's conditions," the EPA said Friday, in announcing the new measures.

Bt corn was approved for sale in 1996, and has seen booming sales ever since. In 1999, more than one third of U.S. corn acres were planted with Bt corn.

caterpillars

Monarch caterpillars on a milkweed leaf dusted with pollen (Photo by Kent Loeffler, courtesy Cornell U.)
In May 1999, researchers at Cornell University released a laboratory study showing that pollen from Bt corn can kill monarch butterflies. That raised fears that the corn pollen could blow from planted fields into nearby meadows, dusting milkweed plants - the sole food of the monarch butterfly caterpillar. No field studies have yet confirmed that Bt corn poses a risk to monarchs outside the laboratory.

However, the potential risk to the butterflies highlights a problem with Bt corn and other modified crops: studies of their impacts have largely been performed in the laboratory or on small test plots. No one is quite sure how they may affect insects in the real world.

In December, the EPA put out a call for further studies to determine how toxic Bt corn may be to species like the monarch and the endangered Karner Blue butterfly. Protocols for these studies are due in March 2000 and the data is due in March 2001.

On Friday, the EPA suggested to the corn industry that farmers should voluntarily plant their required conventional corn refuges upwind of their Bt crops, to prevent Bt corn pollen from blowing onto these fields.

The EPA wants large refuges of conventional corn to reduce the evolutionary pressure that Bt creates on insects. The agency hopes the refuges will delay the evolution of Bt resistance in pest populations. Farmers will not be allowed to spray conventional insecticides on the refuges, unless they can demonstrate that insect pests have exceeded certain levels.

Both biotech seed producers and farmers will have to monitor insect populations for the emergence of insecticide resistance, the EPA says. At the first sign of such resistance, sales of the new seed varieties will be halted.

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Field of genetically modified corn (Photo courtesy Novartis)
Seed producers must develop agreements for farmers to sign stipulating the new EPA rules, and produce educational materials and programs to ensure compliance with the rules. Details of these plans must be submitted to the EPA for approval by January 31.

Last week, Reuters news agency conducted a straw poll of 400 farmers at the annual meeting of the American Farm Bureau Federation. The news agency found that some farmers are planning to stop planting any biotech crops. Faced by pressure from U.S. consumers for labeling of genetically engineered food products, and rejection of all modified ingredients by European consumers, farmers are finding they cannot make a profit on engineered crops.

Even a partial planting of modified crops can make a farmerís entire corn crop unsalable in Europe. As conventional corn planted next to modified Bt corn may take up some of the toxin, much of U.S. corn now tests positive for Bt, and will be rejected by overseas buyers.

The Reuters poll predicts a 24 percent decline in plantings of Bt corn compared with 1999, and a 26 percent decline in plantings of Bt cotton.

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Soy harvest in progress (Photo courtesy American Soybean Association)
The results also predict a 15 percent decline in RoundUp Ready soybeans - a modified variety of soy that makes the plants more tolerant of the Monsanto weed killer RoundUp - and a 22 percent decline in RoundUp Ready corn plantings. RoundUp Ready soy was planted on more than half of all U.S. soy acres in 1999.

For more information on EPA's biotechnology regulatory program for plant pesticides, see: http://www.epa.gov/pesticides/biopesticides.