Scientists confirm: Pesticides kill America's honey
bees
Honey bees are quickly disappearing from the US
– a phenomenon that has left scientists baffled. But new research shows that
bees exposed to common agricultural chemicals while pollinating US crops are
less likely to resist a parasitic infection.
As a result of chemical exposure, honey bees
are more likely to succumb to the lethal Nosema ceranae parasite and die
from the resulting complications.
Scientists from the University of Maryland and
the US Department of Agriculture on Wednesday published a study
that linked chemicals, including fungicides, to the mass die-offs.
Scientists have long struggled to find the cause behind the Colony Collapse
Disorder (CCD), in which an estimated 10 million beehives at an average value
of $200 each have been lost since 2006.
Last winter, the honey bee population declined
by 31.1 percent, with some beekeepers reporting losses of 90 to 100 percent of
their bee populations. Scientists are concerned that “Beemageddon” could cause
the collapse of the $200 billion agriculture industry, since more than 100 US
crops rely on honey bees to pollinate them.
The new findings are key in determining one of
the causes of the CCD, but they fail to explain why entire beehives sometimes
die at once.
UMD and DOA researchers found that pollen
samples in fields ranging from Delaware to Maine contained nine different
agricultural chemicals, including fungicides, herbicides, insecticides and
miticides. One particular sample even contained 21 different agricultural
chemicals. To test their theory, they fed pesticide-ridden pollen samples to
healthy bees and then infected them with the parasite. They found that the
pesticides hindered the bees’ abilities to resist the infection, thus
contributing to their deaths. The fungicide chlorothalonil was particularly
damaging, tripling the risks of parasitic infection.
“We don’t think of fungicides as having a
negative effect on bees, because they’re not designed to kill insects,”
Dennis vanEngelsdorp, the study’s senior author, said in a news release.
He explained that federal regulations restrict
the use of insecticides while pollinators are foraging, but noted that “there
are no such restrictions on fungicides, so you’ll often see fungicide
applications going on while bees are foraging on the crop. The finding suggests
that we have to reconsider that policy.”
Bees are declining at such a fast rate that one
bad winter could trigger an agricultural disaster. California’s almond crop
would be hit particularly hard, since the state supplies 80 percent of the
world’s almonds. Pollinating California’s 760,000 acres of almond fields
requires 1.5 million out-of-state bee colonies, which makes up 60 percent of
the country’s beehives. The CCD is a major threat to this $4 billion industry.
Entomologists suspect that a number of other
factors also contribute to the CCD, including climate change, habitat destructing
and handling practices that expose bees to foreign pathogens. But the effect of
agricultural chemicals is particularly alarming, especially since the US does
not have laws banning the use of the pesticides that are affecting bee health.
“The pesticide issue in itself is much more
complex than we have led to believe,” vanEngelsdorp said.
“It’s a lot more complicated than just one product, which means of course
the solution does not lie in just banning one class of product.”
RT July 25th
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