GE Corn may harm stream ecosystems

A team of stream ecologists from four universities has just released a new study, "Toxins in transgenic crop byproducts may affect headwater stream ecosystems," by Todd V. Royer of Indiana University,

Emma Rosi-Marshall of Loyola University Chicago, Jennifer Tank of the University of Notre Dame and Matt Whiles of Southern Illinois University. From the Southern Illinois University news release:

The group, funded by a grant from the National Science Foundation, examined whether the genetically modified corn plant debris — everything from pollen to husks and cobs — might have unintended impacts on the stream food chain as aquatic insects use it for food. Genetically modified corn such as Bt corn is engineered to create a toxin aimed at destroying the European corn borer, a moth larvae, and other pests that typically feed on corn crops.

The current research focuses on caddisflies, small insects that break down the coarse biomaterial deposited into streams and provide an important food source for other stream life. The researchers chose caddisflies because they are closely related to pests targeted by Bt corn toxin.

Whiles and his graduate student, Catherine Chambers, found caddisflies have slower growth rates when feeding on Bt corn crop debris than when they feed on the non-modified variety. Because smaller insects tend to have fewer eggs, Whiles said it's possible their numbers could decline over time, which might have an overall negative effect on stream food webs.

And here is the abstract from the Proceedings of the National Academies of Sciences website:

Corn (Zea mays L.) that has been genetically engineered to produce the Cry1Ab protein (Bt corn) is resistant to lepidopteran pests. Bt corn is widely planted in the midwestern United States, often adjacent to headwater streams. We show that corn byproducts, such as pollen and detritus, enter headwater streams and are subject to storage, consumption, and transport to downstream water bodies. Laboratory feeding trials showed that consumption of Bt corn byproducts reduced growth and increased mortality of nontarget stream insects. Stream insects are important prey for aquatic and riparian predators, and widespread planting of Bt crops has unexpected ecosystem-scale consequences.

(If you click on Abstract above, you can see the abstract on the PNAS website.  To get the whole article, you need a subscription.)

The Center for Food Safety has this to say:

"This is yet another example of a government agency granting clearance for a GE organism without requiring meaningful or stringent testing," said Joseph Mendelson, Legal Director of the Center for Food Safety.  "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."

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