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Web Site Available on Bt Corn/Monarch Butterflies Case Study / October 2, 2002 / News from the USDA Agricultural Research Service

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Monarch butterfly: Link to web site
"Butterflies and Bt Corn" web site

Web Site Available on Bt Corn/Monarch Butterflies Case Study

By Kim Kaplan
October 2, 2002

A new web site and publication feature how the Bt corn/monarch butterfly controversy was resolved. The electronic and print material present a case study of a controversial issue that was settled by scientifically developed facts.

Photo: A large monarch caterpillar feeds on a common milkweed plant. Link to photo information
Click image for caption and other photo information.

"Butterflies and Bt Corn: Allowing Science to Guide Decisions" was prepared by the Agricultural Research Service, University of Guelph, University of Maryland, Iowa State University, University of Nebraska, Purdue University, Cornell University and Monarch Watch.

The web version of the publication can be found at:

www.ars.usda.gov/sites/monarch

Limited numbers of the printed publication are available from Richard L. Hellmich, USDA-ARS Corn Insect and Crop Genetic Research Unit, 110 Genetics Laboratory, c/o Insectary, Ames, Iowa 50011.

That Bt corn might present a risk became a matter of scientific and public concern when a small study in 1999 indicated caterpillars suffered when given no choice but to feed on milkweed leaves heavily dusted with Bt corn pollen. Bacillus thuringiensis (Bt) is a soil bacterium used as an effective alternative to chemical insecticides for controlling moth pests.

Soon after the controversy began, ARS coordinated a workshop attended by representatives and researchers from government, environmental groups and industry. At that workshop, a cooperative attitude developed that the issue needed credible, science-based facts before any decisions were made.

Two major questions needed to be scientifically answered to establish whether Bt corn actually posed a threat to monarch caterpillars--the direct toxicity of Bt pollen for caterpillars and the likelihood that caterpillars might be exposed to that much pollen.

In the end, monarch caterpillars were not found to be very sensitive to pollen from most types of Bt corn. The study also found that the likelihood of caterpillar exposure to Bt pollen is low.

Data from the researchers involved were combined and five scientific papers were published as a special group in the Proceedings of the National Academy of Sciences. The papers contributed to a decision by the Environmental Protection Agency to renew Bt corn's registration.

ARS is the U.S. Department of Agriculture's chief scientific research agency.

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Last Modified: 10/2/2002
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