Genetically Modified Corn Could Hurt Aquatic Systems

Material from genetically modified (GM) corn could harm aquatic insects and the fish and amphibians that feed on them, according to a new study announced by Indiana University (IU).

A team of researchers from IU, Loyola University Chicago, the University of Notre Dame and Southern Illinois University found that caddisflies that ate leaves from GM corn had growth rates less than half of those without such a diet. They also discovered that a different variety of caddisfly died in higher numbers when exposed to very high levels of GM corn pollen.

Caddisflies "are a food resource for higher organisms like fish and amphibians," said Todd V. Royer, an assistant professor at IU's School of Public and Environmental Affairs. "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."

Royer and other members of the research team tested for signs of GM corn pollen, leaves and cobs in 12 headwater streams in a heavily farmed part of northern Indiana. They found varying levels of GM pollen and other materials in stream water, as well as signs of corn pollen in the guts of certain caddisflies.

While the areas the team covered didn't show levels of GM byproducts high enough to cause the higher fly death rates found in the lab, such levels "could potentially represent conditions in streams of the western Corn Belt," Royer said.

A type of GM corn known as Bt corn is now widely planted across the U.S.; in fact, about 35 percent of farmland for corn was planted with the Bt variety in 2006, according to the U.S. Department of Agriculture. The corn was engineered to include a gene from Bacillus thuringiensis, a microorganism that produces a toxin deadly to crop pests.

While beneficial to the environment, caddisflies are related to the European corn borer and other pests targeted by Bt corn. Before approving Bt corn, the U.S. Environmental Protection Agency tested for potential harm to aquatic insects, but it used a crustacean known as Daphnia rather than an insect more closely related to the pests aimed at by Bt corn.

"Every new technology comes with some benefits and some risks," Royer said. "I think probably the risks associated with widespread planting of Bt corn were not fully assessed."

Other members of the research team that published its findings in this week's Proceedings of the National Academies of Sciences include Emma Rosi-Marshall of Loyola University Chicago, Jennifer Tank of the University of Notre Dame and Matt Whiles of Southern Illinois University.

Indiana University, "Study Shows Genetically Engineered Corn Could Affect Aquatic Ecosystems." URL: (http://newsinfo.iu.edu/news/page/normal/6507.html)