Small doses of pesticide may kill young bees

Palm Beach Post | October 21, 2008
By Susan Salisbuy

GAINESVILLE Tiny doses of pesticides can kill baby bees.

That's what research just completed at the University of Florida found when honey bee larvae were fed a diet laced with miniscule amounts of a nicotine-based pesticide.

The work is considered groundbreaking because so little is known about how chemicals affect developing bees - and because this pesticide, popular among citrus growers, is suspected by Florida beekeepers to cause Colony Collapse Disorder, a mysterious condition which leaves hives deserted, and no bees, alive or dead, in sight. 

Most pesticide research has been conducted on adult bees. 

"My research was on honey bee brood, the larvae and pupae," said Tricia Toth, an entomology graduate student who spent more than seven months on the project. 

Jamie Ellis, assistant entomology professor at UF, said, "Most researchers believe that if chemicals themselves are not doing it, that they certainly exacerbate what is contributing to or causing Colony Collapse Disorder."

First reported in 2006 by a Florida beekeeper, bee and other pollinator problems have received worldwide attention. On Thursday, more than 120 leading scientists and other experts will gather in Washington for a two-day conference hosted by the U.S. State Department. The conference includes a task force report on honey bee health research, including information about pesticides and chemicals.

Imidacloprid, which Toth used in her research, is one of the common pesticides. Sprayed on seeds, the chemical stays in the plant as it grows, and can be found in the pollen and nectar of flowers.

In Florida, the research is timely. Imidacloprid is part of a six-times-a-year spray program UF citrus extension agents are recommending to the state's growers in their fight against the Asian citrus psyllid. The psyllid spreads greening, a bacterial disease that causes trees to produce bitter, misshapen fruit.

Although it's clear the pesticide had a negative effect on young bees, Toth cautions it's not yet possible to draw conclusions about how similar amounts might affect an entire bee colony.

"I can't say this is causing Colony Collapse Disorder," Toth said.

Even so, UF's Ellis said it's alarming to consider how weakened the surviving bees might be under such a scenario.

"What is going to happen to the adults that didn't die as larvae? Tricia's project is likely just scratching the surface," Ellis said.

In August, the Natural Resources Defense Council filed a lawsuit to uncover critical information it contends the U.S. Environmental Protection Agency is withholding about the risks posed by pesticides to honey bees.

"There are persistent concerns in the scientific and bee communities about the role of these pesticides," said council spokesman Josh Mogerman.

The EPA has since posted additional documents on its Web site, but a study produced by Bayer Crop Science still has not been made available.

In a written response to the council, the EPA said it is developing methods to test sub-lethal effects of pesticides on bees.