New requirements to address corn rootworm resistance to Bt Corn

EPAReposted from the Southern IPM Center blog Posted on by rhallberg

In response to signs that the corn rootworm is becoming resistant to single trait Bt products, the Environmental Protection Agency is announcing new, more protective requirements designed to delay corn rootworm resistance to genetically engineered “Bt corn.” Bacillus thuringiensis (Bt) corn produces a Bt pesticide, long used as part of organic farming, as part of the plant itself, to address corn rootworm pests.

When EPA registered Bt corn, EPA ensured that mid-course corrections could be made if additional restrictions on the use of the pesticide were needed to address evolving issues. For example, these corrections could include requirements for additional measures or use restrictions if a specific Bt pesticide begins to lose its effectiveness to kill the corn rootworm. EPA is adding additional requirements to delay pests from becoming resistant.  

These actions will ensure that farmers have safe, effective tools for years to come to control one of the most troublesome pests confronting the nation’s corn growers. Use of Plant Incorporated Protectants (PIPs), including Bt corn, is one of the safest methods of insect control. If used properly, PIP crops greatly reduce the need for conventional pesticides and the risks they may pose to human health and the environment. For these methods to continue to be available, it is essential that they remain effective.

Based in part on an independent science peer review, a letter to the EPA from corn rootworm experts, and public comments to EPA’s docket, measures include:

  • Proactive Integrated Pest Management (IPM), including the rotation of fields to non-Bt corn crops every few years and other changes will greatly reduce resistant corn rootworm populations
  • Proactive early warning efforts will more aggressively and expeditiously detect and address potential problem fields. Companies are required to investigate reports of damage and notify affected companies, neighbors, extension specialists, and crop consultants in areas where populations are found to be resistant.
  • Limitations on specific Bt products on problem and perhaps adjoining fields (depending on the severity of problem) when resistance has been detected. This could include changes in the way farmers use Bt corn, changes in the varieties they choose and other measures. More information about the new requirements can be found at at this site.
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