Study Raises Concern Over Bt Corn Effect On Aquatic Insects

Oct 16: Corn, genetically engineered (GE) to tolerate the pesticide Bacillus thuringiensis (Bt), has been found to harm non-target aquatic insects and disrupt the connected food web. A new study -- Toxins In Transgenic Crop Byproducts May Affect Headwater Stream Ecosystems -- by researchers at Indiana University, funded by the National Science Foundation and published in Proceedings of the National Academies of Sciences, suggests that the crop, which has been licensed for use since 1996, poses an unforeseen risk to aquatic ecosystems.

According to the study, roughly 35 percent of American corn acreage is Bt corn. Pollen and other parts of the plants are traveling much farther than the fields in which they are planted, carrying Bt toxins through watersheds and being consumed by close relatives of the corn’s targeted pests. Caddisflies experience high mortality and stunted growth as a result of exposure. As researcher Todd Royer observed, they “are a food resource for higher organisms like amphibians and fish. 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.”

This effect went unnoticed for ten years because the Environmental Protection Agency (EPA), in its registration trials, tested Bt on a crustacean, rather than the aquatic insects that are being affected. “Every new technology comes with some benefits and some risks,” said Royer. “I think probably the risks associated with widespread planting of Bt corn were not fully assessed.”

The Center for Food Safety voiced concern regarding a study. Joseph Mendelson, Legal Director of the Center for Food Safety said, "This is yet another example of a government agency granting clearance for a GE organism without requiring meaningful or stringent testing. Bt corn is planted widely throughout the U.S. Had a study like this been done prior to the government's approval, we would not be looking at a popular crop that has the potential to broadly disrupt the environment." The Center said that Caddisflies are imperative to healthy, normally functioning stream ecosystems; they serve as food for fish, birds, reptiles, and amphibians.

Access a release from Beyond Pesticides (click here). Access a release from the Center for Food Safety (click here). Access the published paper (click here). [*Toxics]