http://www.motherearthnews.com/Nature-Community/Colony-Collapse-Pesticides-Bees.aspx
Colony Collapse: Are Potent Pesticides Killing Honeybees?
With a third of honeybee colonies disappearing due to “colony collapse
disorder,” it’s time to move into high gear to find a solution.
October/November 2009
By Amanda Kimble-Evans
Two common pesticides are being linked to colony collapse disorder
symptoms in honeybees.
EDITED

Now the EPA is being sued by the nonprofit Natural Resources Defense
Council (NRDC) for withholding details about the impact of
neonicotinoids — a class of widely used pesticides — on honeybees and
other pollinators.

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.

Frazier also highlights a study from North Carolina University that
found the neonicotinoid Terraguard and the fungicide Procure had
synergistic affects when combined, increasing the danger of the
neonicotinoid to honeybees to over 1,000 times its original toxicity.
The researchers at Penn State are concerned that even sub-lethal doses
of these pesticides, while not killing the bees, are impairing their
behavior and suppressing their immune systems.

“Their use has increased dramatically over the past few years and they
are now the most widely used group of insecticides in the United
States,” writes Frazier.

As usage skyrockets, regulation lags behind. Clothianidin was approved
in 2003 with the condition that Bayer must provide research on the
chemical’s effects on honeybees. The EPA has received the research,
but has yet to release all of it — despite requests from the NRDC,
thus prompting the lawsuit. The EPA has also provided 163 emergency
exemptions for imidacloprid in 26 states, all with little to no
research on the sub-lethal affects being reported by researchers in
both the US and abroad. (Emergency exemptions allow unregistered use
of a chemical for a limited period of time.)

Pesticide regulation loopholes are making it nearly impossible to
track down the causes of colony collapse disorder.