Researchers Todd V. Royer, an assistant professor in the IU School of Public and Environmental Affairs and his colleagues found in laboratory trials that the consumption of Bt corn byproducts produced increased mortality and reduced growth in caddisflies, aquatic insects related to pests targeted by the toxin in Bt corn.
"Caddisflies, are a food resource for higher organisms like fish and amphibians. And, if our goal is to have healthy, functioning ecosystems, we need to protect all the parts. Water resources are something we depend on greatly," said Prof. Royer.
Bt corn is engineered to include a gene from the micro-organism Bacillus thuringiensis, which produces a toxin that protects the crop from pests, in particular the European corn borer.
It was licensed for use in 1996 and quickly gained popularity.
In 2006, around 35 percent of corn acreage planted in the US was genetically modified.
Prof. Royer said before licensing Bt corn, the US Environmental Protection Agency conducted trials to test its impact on water biota. But it used Daphnia, a crustacean commonly used for toxicity tests, and not insects that are more closely related to the target pests.
The study, "Toxins in transgenic crop byproducts may affect headwater stream ecosystems" appears in this week's online issue of the journal Proceedings of the National Academies of Sciences.