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Bt Corn Has Been Approved for Continued Use

November 9, 2001
On Tuesday, October 16, 2001, the United States Environmental Protection Agency (EPA) announced that it had approved the use of "corn genetically modified with Bacillus thursingiensis" (Bt corn) for another 7 years. This was good news for corn growers throughout the United States who have to contend with infestations of European and southwestern corn borers. The EPA approved the continued use of Bt corn after a comprehensive scientific review, despite the negative press generated during the past couple of years (negative press that often was not based on scientific evidence). Stephen L. Johnson, assistant administrator of EPA's Office of Prevention, Pesticides and Toxic Substances, indicated that scientific studies and a history of successful use have demonstrated that Bt corn does not pose risks to human health or to the environment.

Of particular concern during the scientific review process were the potential risks that Bt corn posed to monarch butterflies. The EPA requested extensive data from the scientific community in order to evaluate the potential concern. And as we reported in an article in issue no. 23 (October 5, 2001) of the Bulletin, the scientific evidence has demonstrated convincingly that Bt corn does not have a negative effect on monarch butterfly populations. EPA has also has determined that there will be no effects to endangered species from the use of the currently registered Bt corn products.

Not surprisingly, and similar to the renewed registration of Bt cotton (issue no. 23 of the Bulletin, October 5, 2001), the renewed registration of Bt corn emphasizes some of the primary issues associated with transgenic crops. To ensure that Bt corn continues to be a safe and effective tool for farmers, EPA has mandated several provisions to strengthen insect resistance management, to increase research data on potential environmental effects, and to improve grower education and stewardship.

Regarding environmental effects, EPA is requesting additional data on the persistence of the active Bt protein in soil, more field studies on nontarget insects, studies examining long-term effects on monarch butterfly populations, an additional feeding study for bird species, and monitoring of the behavior of particular pest populations and their north­south movement through the country. Although the scientific evidence to date does not suggest negative effects of Bt corn within the environment, continued studies are appropriate.

More onus has been placed on companies marketing Bt corn seed to monitor for the development of insect resistance, provide annual reports on the efficacy of resistance management plans, and implement remedial action plans in the event that resistance is detected among pest populations. The companies also must educate growers about the best methods of planting Bt corn to minimize potential development of insect resistance. Although the companies have been responsible for these types of activities from the outset, there are more "teeth" in the renewed registrations:

· All growers who wish to plant Bt corn must sign contractual grower agreements, which set forth the terms and conditions for use.

· Companies are required to implement a system to secure signatures on the grower agreements before the growers can receive the Bt corn seed.

· Companies must make the grower agreements available to EPA.

· To monitor the new requirements, an independent, third-party compliance survey of licensed growers will be conducted annually for the duration of the registrations. (I find the use of the term "licensed" to be a bit disturbing.)

Detailed information about EPA's decision regarding Bt corn is available at

We concur with EPA's emphasis on resistance management and continued studies to examine the effects of Bt corn in the environment. These, after all, were supposed to be important aspects of the initial registration of Bt corn. Now that some of the "flap" about Bt corn has settled down, let's all remember that it's up to us to do the right things to ensure continued use of Bt corn and the use of future transgenic crops.--Kevin Steffey and Mike Gray

Author: Kevin Steffey Mike Gray

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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