The finding comes from the first large-scale study that simultaneously examined how growing Bt cotton affects yield, pesticide use and biodiversity.

It's good news for the environment.

"What we see is that it's positive here in Arizona -- no doubt about it," said Yves Carrire, an associate professor of entomology at The University of Arizona in Tucson. "We've reduced pesticide use in Arizona. We've wanted to do that for 25 years."

Bt cotton has been genetically altered to produce Bt toxin, a naturally occurring insecticide that kills pink bollworm, a major pest of cotton. Bt cotton has been planted in Arizona since 1996. Now more than half of the state's 256,000 acres of cotton fields are planted with the biotech plants.

Some have suggested that, in addition to killing the target pests, insecticide-containing crops like Bt cotton would also kill beneficial and non-target arthropods.

The new study found that Bt cotton, also known as transgenic cotton, does not affect the biodiversity of insects in cotton fields.

Carrire said, "There were lots of factors that affected biodiversity in this study. Transgenics were not one of them."

He and his colleagues based their findings on a two-year study of 81 commercial cotton fields in a region of Arizona that spans about 2,500 square miles (6,600 square kilometers). Much of the field and lab work was done by Manda G. Cattaneo as part of her master's research at UA. Cattaneo is now an extension entomologist at Texas A&M University in College Station.

The multidisciplinary team will publish their research in an upcoming issue of the Proceedings of the National Academy of Sciences. A complete list of authors is at the end of this release. The Environmental Prote
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Contact: Mari N. Jensen
mnjensen@email.arizona.edu
520-626-9635
University of Arizona
1-May-2006