Powerful Insecticide Turns up in Major Midwest Rivers

A pervasive agricultural insecticide that has been linked to the decline of honeybees is now a near-constant presence in the small and great rivers that flow through Midwestern farm country, according to the first major review of its kind.

July 25, 2014 | Source: Star Tribune | by Josephine Marcotty

For related articles and information, please visit OCA’s Environment and Climate Resource Center page and our Honey Bee Health page.

A pervasive agricultural insecticide that has been linked to the decline of honeybees is now a near-constant presence in the small and great rivers that flow through Midwestern farm country, according to the first major review of its kind.

Scientists at the U.S. Geological Survey tracked the toxins called neonicotinoids in six states and nine Midwestern rivers, including the portion of the Mississippi that drains southern Minnesota, and found that they were universally present throughout the growing season in every watershed tested.

The results, published this week, raise significant questions about possible threats to the insects that form the base of the food chain in aquatic ecosystems, and they follow another study last month that found sharp declines in birds wherever the insecticides were widely used in Holland.

“If you get enough rain to transport it over land or into tile drains, then it gets into streams quite quickly at higher concentrations,” said Kathryn Kuivila, a scientist at the USGS Oregon Water Science Center in Portland, Ore., and a lead author of the study.

The concentrations found by the study are lower than those the U.S. Environmental Protection Agency (EPA) considers fatal to aquatic insects, she said. But other scientists have found that the EPA’s estimates for toxicity may be too high.

“Even more importantly, these organisms are not exposed to just one neonicotinoid,” Kuivila said. “And there are other pesticides, other stressors.”

Neonicotinoids, a synthetic nicotine, are neurotoxins whose use has exploded since they were first introduced in the mid-1990s. They are now the most widely used insecticide in the world, having quickly replaced older classes of chemicals that were far more toxic to humans and mammals.