http://www.gantdaily.com/
September 16th, 2008
Andrea Messer and Vicki Fong, Penn State University
Pesticide Buildup Could Lead to Poor Honey Bee Health
PHILADELPHIA - IHoney bees
industriously bring pollen and nectar to the hive, but along with the
bounty comes a wide variety of pesticides, according to Penn State
researchers. Add the outside assault to the pesticides already in the
waxy structure of the hive, and bee researchers see a problem difficult
to evaluate and correct. However, an innovative approach may mitigate
at least some beeswax contamination.
The researchers present
their analysis of pollen, brood, adult bees and wax samples today at
the 236th national American Chemical Society meeting in Philadelphia.
Those results show unprecedented levels of fluvalinate and coumaphos --
pesticides used in the hives to combat varroa mites -- in all comb and
foundation wax samples. They also found lower levels of 70 other
pesticides and metabolites of those pesticides in pollen and bees.
"Everyone
figured that the acaricides (anti-varroa mite chemicals) would be
present in the wax because the wax is reprocessed to form the structure
of the hives," says Maryann Frazier, senior extension associate. "It
was a bit of a shock to see the levels and the widespread presence of
these pesticides."
While the researchers expected the presence
of the chemicals available to treat varroa mites in the hives, the
other pesticides' levels were also surprising. All of the bees tested
showed at least one pesticide and pollen averaged six pesticides with
as many as 31 in a sample.
"We already had in place ways to
test for viruses, bacteria and fungi, but it was difficult to find an
analytical laboratory that could analyze for unknown pesticides," says
Christopher A. Mullin, professor of entomology. "We needed them to take
a comprehensive look at all pesticides, not just those associated with
beekeeping."
They eventually turned to the National Science
Laboratory of the U.S. Department of Agricultural Marketing Service
that already tests commodities such as milk and fruits and vegetables
to allow them to meet national and international standards.
"When
we began doing this work, honey was not regularly analyzed, and bee
pollen was not a commodity and so was not analyzed," says Mullin. "We
decided to go with the types of screening the lab does for milk and
apples which look at over 170 pesticides. Now, honey is included in the
commodities to be analyzed."
The researchers, including Roger
Simonds, a chemist at the National Science Laboratory decided on a
modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe)
method because it uses smaller samples. They coupled this with gas and
liquid chromatography to develop methods of analyzing pollen, bees and
wax.
"Simplicity was important because there were many people
across the country sampling for us," says Maryann Frazier. "Now rather
than having them collect 15 grams of pollen they need only collect 3
grams."
The researchers note that this method also uses less solvent and generates data in the parts per billion range.
While
beekeepers will have a difficult time controlling pesticide exposure
outside the hive, the researchers tested a method for reducing the
acaricide load in beeswax. Using gamma radiation from a cobalt 60
source housed at Penn State's Breazeale Reactor, they irradiated the
sheets of beeswax that beekeepers use as the structural foundation for
the bees to build their combs. They used radiation levels at the high
end of that used to irradiate foods. Irradiation broke down about 50
percent of the acaricides in the wax.
"Gamma radiation is
often used to kill viruses and other disease causing agents," says
James L. Frazier, professor of entomology, Penn State. "Commercial
irradiation firms usually decontaminate medical instruments or foods."
The
researchers tried irradiation at a commercial plant and though some
modifications were necessary to irradiate the wax sheets, it is
possible. Some beekeepers already irradiate their equipment to get rid
of any disease causing agents. However, it might be more efficient if
the wax sheet supplier irradiated their product before sale to the
beekeepers.
Beekeepers cannot manage the environmental
pesticide contamination as easily as the wax contamination. The U. S.
Environmental Protection Agency does regulate and monitor pesticides,
but they do not have the ability to monitor the interaction of these
chemicals. With the large number of pesticides found in bees and
pollen, interactions are likely.
"We are finding fungicides
that function by inhibiting the steroid metabolism in the fungal
diseases they target, but these chemicals also affect similar enzymes
in other organisms," says James Frazier. "These fungicides, in
combination with pyrethroids and/or neonicotinoids can sometimes have a
synergistic effect 100s of times more toxic than any of the pesticides
individually."
For CCD, bees are not dying in their hives, but
are not returning to their hives. James Frazier notes it is difficult
to observe bees outside the hive. The U.S. EPA only looks at acute
exposure to individual pesticides, but chronic exposure may cause
behavioral changes that are unmonitored.
"We do not know that
these chemicals have anything to do with Colony Collapse Disorder, but
they are definitely stressors in the home and in the food sources,"
says Dr. Frazier. "Pesticides alone have not shown they are the cause
of CCD. We believe that it is a combination of a variety of factors,
possibly including mites, viruses and pesticides."
The
researchers, who also include Sara Ashcraft, research assistant, have a
team uniquely suited to looking at the honey bee pesticide problem
because they combine a toxicologist in Mullin, a physiologist in James
Frazier and someone with connections to beekeepers across the country
in Maryann Frazier.
"We now want to look at small versus large
operations and organic versus nonorganic operations to see if there are
differences," says Maryann Frazier.
The U.S. Department of
Agriculture, the National Honey Board, beekeeper organizations and
concerned individuals supported this work.A -
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