Colony Collapse Disorder: Are Potent Pesticides Killing Honeybees?

By Amanda Kimble-Evans
Published on August 25, 2009
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PHOTO: ISTOCKPHOTO
Two common pesticides have been linked to colony collapse disorder symptoms in honeybees.

Colony collapse disorder has wreaked havoc on U.S. beekeeping businesses (and the agriculture industry) since its devastating arrival in 2006. The veiled killer entered hives across Japan for the first time earlier this year, affecting 25 percent of the national beekeeping association members. Now the nonprofit Natural Resources Defense Council (NRDC) is suing the U.S. Environmental Protection Agency (EPA) for withholding details about the impact of neonicotinoids — a class of widely used pesticides — on honeybees and other pollinators.

Nasty Neonicotinoid Pesticides

The EPA identifies two specific neonicotinoids, imidacloprid, and clothianidin, as highly toxic to bees. Both chemicals cause symptoms in bees such as memory loss, navigation disruption, paralysis, and death.

Both chemicals have been linked in dramatic honeybee deaths and subsequent suspensions of their use in France and Germany. Several European countries have already suspended them. Last year Slovenia and Italy also suspended their use for what they consider a significant risk to honeybee populations.

While Bayer CropScience, the primary producer of both pesticides, maintains honeybee deaths reported in Europe were caused by unusual application errors, they don’t dispute the proven toxicity of their products. Instead, they maintain bees do not encounter enough of an exposure to cause harm. Now even that assertion is under the microscope.

A report by Maryann Frazier, senior extension associate at Pennsylvania State University, points to a new study from Italy suggests honeybees may be ingesting neonicotinoids at levels 1,000 times higher than that in pollen or nectar via water droplets expressed from the leaves of corn grown from the pesticide-coated seed. This “guttation water” is a common source of liquid for forager bees. The concentrations in the droplets were high enough to kill bees within five minutes of consumption.

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