Seed Corn Treatment Finding Stirs Up Hornet's Nest

Purdue and Connecticut researchers link Poncho seed corn treatment to honey bee deaths. Bees pick up dust from planter exhausts found on soil and flowers.

Published on: Jan 11, 2012

Last week's research report release by scientists at Purdue University and the Connecticut Ag Experiment Station documented major adverse impacts from clothianidin, a seed corn treatment branded as Poncho. And it has stirred up an angry horde in the bee keeping industry and environmental community.

In fact, the Sierra Club is calling on U.S. Environmental Protection Agency to immediately suspend registration of the insecticide. "This research should nail the coffin lid shut on clothianidin", contends Laurel Hopwood, Sierra Club chairwoman of the Genetic Engineering Action Team. "Despite numerous attempts by the beekeeping industry and conservation organizations to persuade the EPA to ban clothianidin, the EPA has failed to protect the food supply for the American people."

Last weeks research report release by scientists at Purdue University and the Connecticut Ag Experiment Station documented major adverse impacts from clothianidin, a seed corn treatment branded as Poncho. And it has stirred up an angry horde in the bee keeping industry and environmental community.
Last week's research report release by scientists at Purdue University and the Connecticut Ag Experiment Station documented major adverse impacts from clothianidin, a seed corn treatment branded as Poncho. And it has stirred up an angry horde in the bee keeping industry and environmental community.

What the research discovered

The research, published in the PLoS One scientific journal, found high levels of clothianidin and thiamethoxam in planter exhaust materials during planting of treated seed corn. The work was conducted by Purdue Entomologist Christian Krupke and University of Connecticut Ag Experiment Station Chemist Brian Eitzer.

"Our results demonstrate that bees are exposed to these compounds and several other pesticides in several ways throughout their foraging period," notes Krupke. "We also found neonicotinoids in the soil of each field sampled, including unplanted fields.

"Plants (dandelions) visited by foraging bees growing near these fields were found to contain neonicotinoids as well. This indicates deposition of neonicotinoids on the flowers, uptake by the root system, or both."

Dead bees collected near hive entrances during the spring sampling period also contained clothianidin. But it was unclear whether exposure was oral (consuming pollen) or by contact (soil/planter dust). Clothianidin was also detected in pollen collected by bees and stored in the hive.

When the seed corn pollinated, its pollen also contained clothianidin and other pesticides. "These results have implications for a wide range of large-scale annual cropping systems that utilize neonicotinoid seed treatments," summarizes Krupke. The research was funded by grants from the North American Pollinator Protection Campaign and the Managed Pollinator Coordinated Agricultural Project.

The report notes that the half-lives of neonicotinoid compounds in aerobic soil conditions vary widely. For clothianidin, it ranges from 148 to 1,155 days.