North American Native Bees: Neonicotinoid Pesticide Exposure

Much of our news about bees is regarding European honeybees and sometimes bumblebees, but a recent study indicated that native North American bees have residues from neonicotinoid insecticides and other pesticides. The former have been associated with bee colony collapse. The recent report, by the U.S. Geological Survey, was published in the journal Science of the Total Environment.

"We found that the presence and proximity of nearby agricultural fields was an important factor resulting in the exposure of native bees to pesticides," said USGS scientist Michelle Hladik, in a release. "Pesticides were detected in the bees caught in grasslands with no known direct pesticide applications."

The researchers in the study collected native bees from cultivated fields of crops as well as grasslands in northeastern Colorado. Then they processed the bee samples, checking for 122 pesticides and 14 chemicals that result from the breakdown of pesticides. They looked for these presences in and on the bees, said the release.

Neonicotinoid insecticide thiamethoxam was the most commonly found pesticide, occurring in 46 percent of the composite bee samples. That pesticicide occurs as a seed coating on many crops. Not all samples contained pesticides; 15 out of the 54 total samples had negative results for the 122 chemicals tested.

The United States has about 4,000 native species of bees. They preceeded the European honeybees brought by settlers, and they are pollinators of native plants that include blueberries, cranberries and cherries. Many native bees also pollinate agricultural crops. More about these bees is found at the USGS Bee Inventory website.

"This foundational study is needed to prioritize and design new environmental exposure experiments on the potential for adverse impacts to terrestrial organisms," said Mike Focazio with the USGS, in the release. "This and other USGS research is helping support the overall goals of the White House Strategy to Promote the Health of Honey Bees and Other Pollinators by helping us understand whether these pesticides, particularly at low levels, pose a risk for pollinators."