For a collection of articles and submissions on the current EPA reregistration of BT crops: http://www.biotech-info.net/Bt_rereg.html
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Scientists fear new threat to butterflies from Bt corn
Reuters - USA: September 14, 2001
http://www.planetark.org/dailynewsstory.cfm/newsid/12403/story.htm

WASHINGTON - Four experts on biotech crops and monarch butterflies have urged the Environmental Protection Agency to renew Bt corn registrations for only one year and to investigate a new risk the plant may pose to the orange-and-black butterflies.

The four scientists at Iowa State University, Cornell University and the University of Minnesota were among more than a dozen others who recently authored papers for the National Academies of Science on the risk to monarch caterpillars of windblown pollen from genetically engineered Bt corn.

Bt corn is a variety engineered to produce the pesticide Bacillus thurigiensis, which protects growing corn plants from destructive pests. The scientific papers showed little, if any, risk from Bt corn pollen eaten by the butterflies, but questioned whether there was danger from a plant tissue known as corn anther.

The Environmental Protection Agency is mulling the proposed renewal of several Bt corn and cotton registrations that expire on Sept. 30. The varieties were first approved by the EPA six years ago.

But some of the same research scientists told the EPA that a licensing decision now would be "premature" because more studies are needed to determine the risk for caterpillars that eat Bt pollen and corn anther.

"The presence of anthers on milk weeds is of considerable importance because of the higher concentrations of Bt toxins that they contain," said John Losey, an entomologist at Cornell University.

Losey, along with John Obrycki and Laura Jesse of Iowa State University and Karen Oberhauser of the University of Minnesota, urged the EPA to take a closer look at the risk of corn anthers.

Unpublished field studies conducted in Iowa cornfields last summer showed a 50 percent lower survival rate for monarch caterpillars which ate a mixture of Bt pollen and anther, the scientists said in a letter to the EPA, dated Sept. 11.

"We urge, at the very least, that the registrations of Bt corn be limited to one year," they said. In the meantime, the agency should require new research on the risk of corn anthers and review all data again next year, the scientists said.

The biotech industry has pressed for renewal of the EPA registrations, contending that the benefits of Bt crops far outweigh any risks.

The set of National Academies of Science papers found there was less than a 2 percent chance of a monarch caterpillar being exposed to Bt corn pollen.

The risk is low because the plants shed pollen during a brief 10-day period, which must coincide with the dates when the monarch larvae are present, according to the authors. Reducing the risk, too, is the fact that only 19 percent of U.S. corn fields were planted with Bt varieties this year.