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A new study found a class of insecticides popular with corn and soybean farmers in Midwest waterways. (File: Amy Mayer/Harvest Public Media)
A new study found a class of insecticides popular with corn and soybean farmers in Midwest waterways. (File: Amy Mayer/Harvest Public Media)

Powerful chemicals used by many farmers to ward off insects are making their way into Midwest rivers and streams, according to a study by the U.S. Department of the Interior and the U.S. Geological Survey (USGS).

Neonicotinoids, a class of insecticides popular with corn and soybean farmers, are similar to nicotine and have recently been blamed by some as a factor in the decline of U.S. bee colonies and other crop and flower pollinators. And the USGS study found the chemicals were common in streams throughout the Midwest.

“One of the reasons we thought it was really important to do this study was because the neonicotinoid use has increased quite dramatically in the last ten years in the Midwest,” said USGS scientist Kathy Kuivila, who led the research team. “Other insecticides are going away, the neonicotinoid use is increasing.”

For four generations, Riley Lewis’ family has farmed a plot of land near Forest City, Iowa. Lewis currently raises corn, soybeans and hogs. (Amy Mayer/Harvest Public Media)
For four generations, Riley Lewis’ family has farmed a plot of land near Forest City, Iowa. Lewis currently raises corn, soybeans and hogs. (Amy Mayer/Harvest Public Media)

In his home in Forest City, Iowa, Riley Lewis has the original warranty deed for his farm, signed by President James Buchanan and issued to one Elias Gilbert, a soldier who served in the War of 1812.

“He moved here, northeast of Forest City, and lived there for one year,” Lewis said, which was the obligation veterans had if they homesteaded. “And then he sold it to Robert Clark, who was the founder of Forest City.”

In 1871, Lewis’ great-grandfather bought 40 acres of that original homestead. Over the years, Lewis’ family acquired the rest of the 160 acres and has farmed here ever since.

The USDA reports that 93 percent of the corn planted in the United States contains a genetically modified trait. (Amy Mayer/Harvest Public Media)
The USDA reports that 93 percent of the corn planted in the United States contains a genetically modified trait. (Amy Mayer/Harvest Public Media)

Genetically modified seeds have been embedded with a gene—usually from a bacteria—that protects the corn from pests or herbicides. And the percentage of  genetically modified seed within the U.S. corn crop nearly doubled over the past 10 years, from less than half of the total planted corn acres in 2004 to 93 percent this year, up from 90 percent last year.

Soybeans have a slightly higher figure, at 94 percent containing a genetic modification, but those seeds have been available longer. In 2004, already 85 percent of soybeans contained an engineered trait.

Iowa State University extension agronomist Mark Johnson says the leap in corn adoption is partly thanks to the success of the first genetically modified corn seed, which fought off a bug called the European corn borer.

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