(Beyond Pesticides, October 16, 2007)
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 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 travelling 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 V. 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.”
This risk to aquatic life increases as the demand for corn grows. James Raich, a National Science Foundation program director, warned that “increased use of corn for ethanol is leading to increased demand for corn and increased acreage in corn production. Previous concerns about the nutrient enrichment in streams that accompany mechanized row-crop agriculture are now compounded by toxic corn byproducts that enter our streams and fisheries, and do additional harm.”
Bt corn, along with other genetically GE crops like soybeans and rice, has been controversial in some states and studies, whether over its environmental impact or economic value. In addition to this study’s findings among non-target species, it raises fears of pesticide resistance in target species, contamination of non-GE crops, and corporate monopolies on seed. For more on genetic engineering, click here.