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<a href="http://www.chicagotribune.com/business/sns-rt-us-beesbre89k0cp-20121021,0,5618851.story">
http://www.chicagotribune.com/business/sns-rt-us-beesbre89k0cp-20121021,0,5618851.story</a>
<br><br>
<h1><b>chicagotribune.com<br><br>
<br>
</b></h1><h2><b>Pesticides put bumblebee colonies at risk of
failure</b></h2>Alister Doyle<br><br>
Reuters<br><br>
12:43 PM CDT, October 21, 2012<br><br>
OSLO (Reuters) - Pesticides used in farming are also killing worker
bumblebees and damaging their ability to gather food, meaning colonies
that are vital for plant pollination are more likely to fail when they
are used, a study showed on Sunday.<br><br>
The United Nations has estimated that a third of all plant-based foods
eaten by people depend on bee pollination and scientists have been
baffled by plummeting numbers of bees, mainly in North America and
Europe, in recent years.<br><br>
British scientists said they exposed colonies of 40 bumblebees, which are
bigger than the more common honeybee, to the pesticides neonicotinoid and
pyrethroid over four weeks at levels similar to those in fields.<br><br>
Neonicotinoids are nicotine-like chemicals used to protect various crops
from locusts, aphids and other pests.<br><br>
"Chronic exposure ... impairs natural foraging behavior and
increases worker mortality, leading to significant reductions in brood
development and colony success," the scientists wrote in the report
in the journal Nature on Sunday.<br><br>
Exposure to a combination of the two pesticides "increases the
propensity of colonies to fail", according to the researchers at
Royal Holloway, University of London.<br><br>
A 2011 U.N. report estimated that bees and other pollinators such as
butterflies, beetles or birds do work worth 153 billion euros ($200
billion) a year to the human economy and are in decline in many
nations.<br><br>
The findings underscored the importance of wider testing of pesticides to
ensure they do not also target bees, it said.<br><br>
France banned a neonicotinoid pesticide made by Swiss agrochemicals group
Syngenta in June, citing evidence of a threat to the country's bees. A
report last month, however, said that the original research was
flawed.<br><br>
"My guess is that the decline of bees is like a jigsaw -there are
probably a lot of pieces to put into place. This is probably a very
important piece of that jigsaw," lead author Richard Gill told
Reuters of the findings about pesticides.<br><br>
PARASITES<br><br>
In a separate commentary in Nature, Juliet Osborne of the University of
Exeter in England said the study underscored the need to understand all
factors that may contribute to harm bees and to "Colony Collapse
Disorder".<br><br>
"For example, we have as yet no convincing demonstration of the
relative effects of pesticides on bee colonies compared to the effects of
parasites, pathogens and foraging resources," she wrote.<br><br>
Gill endorsed recommendations by the European Food Safety Authority for
longer testing on adult bees and larvae, new ways of assessing cumulative
exposure to toxins and separate assessments for different bee
species.<br><br>
He said previous studies had mostly examined the impact of pesticides on
individual bees, rather than colonies. Bumblebees form colonies of a few
dozen bees, while honeybees can number up to tens of thousands.<br><br>
"Effects at the individual level can have a major knock-on effect at
the colony level. That's the novelty of the study," he
said.<br><br>
The average number of bees lost in the experiment - both dead in the
nesting box and failing to return - was about two-thirds of the total for
bees exposed to a combination of the two pesticides against a third for a
control, exposed to neither.<br><br>
Bumblebees exposed to a combination of pesticides were about half as
successful at gathering pollen, used as food, compared to a control. They
also devoted more workers to collecting food, meaning fewer were raising
larvae.<br><br>
Other experts said more research was needed. "It certainly wouldn't
be fair to say that this research spells doom for wild bees," said
James Cresswell of the University of Exeter.<br><br>
(Editing by Alison Williams)<br><br>
Copyright © 2012, Reuters<br>
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