Insecticides from genetically modified corn present in adjacent streams
The issue of genetically modified food has come up a lot in the media lately, people are realizing that genetically modified foods or GMO’s can be quite dangerous. And time after time, we see that the testing that we expect to be done on these products to guarantee there safety, is either not done or the results are faked. It makes it difficult for consumers to know what to believe but, papers like this one written for the Cary Institute help us make our decisions about what to buy and even more important what to feed our families. This isn’t the first case of runoff water being an issue from GM plants, and should make people realize that banning there use until they are fully understood is extremely important. Whether it’s water run off in the American Midwest, or rice failures in Africa. We all have to be aware and make the decision to carefully regulate genetic modification of our food supply.
Stream ecosystems are tightly linked to agricultural fields and should be considered when adopting new agricultural technologies
In a paper published this week in the Proceedings of the National Academy of Sciences, Cary Institute aquatic ecologist Dr. Emma Rosi-Marshall and colleagues report that streams throughout the Midwestern Corn Belt are receiving insecticidal proteins that originate from adjacent genetically modified crops. The protein enters streams through runoff and when corn leaves, stalks, and plant parts are washed into stream channels.
Genetically-modified plants are a mainstay of large-scale agriculture in the American Midwest, where corn is a dominant crop. In 2009, more than 85% of U.S. corn crops were genetically modified to repel pests and/or resist herbicide exposure. Corn engineered to release an insecticide that wards off the European corn borer, commonly referred to as Bt corn, comprised 63% of crops. The tissue of these plants has been modified to express insecticidal proteins, one of which is commonly known as Cry1Ab.
Following an assessment of 217 stream sites in Indiana, the paper’s authors found dissolved Cry1Ab proteins from Bt corn present in stream water at nearly a quarter of the sites, including headwater streams. Eighty-six percent of the sampled sites contained corn leaves, husks, stalks, or cobs in their channels; at 13% of these sites corn byproducts contained detectable Cry1Ab proteins. The study was conducted six months after crop harvest, indicating that the insecticidal proteins in crop byproducts can persist in the landscape.
Using these data, U.S. Department of Agriculture land cover data, and GIS modeling, the authors found that all of the stream sites with detectable Cry1Ab insecticidal proteins were located within 500 meters of a corn field. Furthermore, given current agricultural land use patterns, 91% percent of the streams and rivers throughout Iowa, Illinois, and Indiana —some 159,000 miles of waterways—are also located within 500 meters of corn fields.
Rosi-Marshall comments, “Our research adds to the growing body of evidence that corn crop byproducts can be dispersed throughout a stream network, and that the compounds associated with genetically-modified crops, such as insecticidal proteins, can enter nearby water bodies.”
After corn crops are harvested, a common agricultural practice is to leave discarded plant material on the fields. This “no-till” form of agriculture minimizes soil erosion, but it also sets the stage for corn byproducts to enter nearby stream channels.
Rosi-Marshall concludes, “The tight linkage between corn fields and streams warrants further research into how corn byproducts, including Cr1Ab insecticidal proteins, potentially impact non-target ecosystems, such as streams and wetlands.” These corn byproducts may alter the health of freshwaters. Ultimately, streams that originate in the Corn Belt drain into the Mississippi River and the Great Lakes.
Other authors on the PNAS paper included first-author Dr. Jennifer L. Tank (University of Notre Dame) and Drs. Todd V. Royer (Indiana University), Matthew R. Whiles (Southern Illinois University), Natalie A. Griffiths (University of Notre Dame), Therese C. Frauendorf (University of Notre Dame), and David J. Treering (Loyola University Chicago).
The Cary Institute of Ecosystem Studies is a private, not-for-profit environmental research and education organization in Millbrook, N.Y. For more than twenty-five years, Cary Institute scientists have been investigating the complex interactions that govern the natural world. Their objective findings lead to more effective policy decisions and increased environmental literacy. Focal areas include air and water pollution, climate change, invasive species, and the ecological dimensions of infectious disease. Learn more at www.caryinstitute.org