ot: interactions between pesticides and pathogens - Pesticides blamed for bee decline

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Various researchers have found that intra-body pollutants impair

immunity and enhance the likelihood of adverse effects from pathogens.

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Pesticides blamed for bee decline

New formulas make colonies more prone to disease, research finds.

Owen

Sunday 29 January 2012

http://www.independent.co.uk/environment/nature/pesticides-blamed-for-bee-declin\

e-6296322.html

Compelling new evidence from the US government's top bee expert that

modern pesticides may be a major cause of collapsing bee populations led

to calls yesterday for the chemicals to be banned.

A study published in the current issue of the German science journal

Naturwissenschaften, reveals how bees given minute doses of the widely

used pesticide imidacloprid became more vulnerable to infections from a

deadly parasite, nosema.

Bee experts described this as clear evidence of the role pesticides play

in the plight of bees. Although research into the furry insects may seem

like a very academic exercise, bees are vital to human survival. More

than 70 of the 100 crops that provide 90 per cent of the world's food

are pollinated by bees, and Albert Einstein once predicted that if bees

died out, " man would have no more than four years to live. "

The study, led by Dr Pettis, the head of the US Department of

Agriculture's Bee Research Laboratory, says: " We believe that subtle

interactions between pesticides and pathogens, such as demonstrated

here, could be a major contributor to increased mortality of honey bee

colonies worldwide. "

Researchers found that bees deliberately exposed to minute amounts of

the pesticide were, on average, three times as likely to become infected

when exposed to a parasite called nosema as those that had not. The

findings...

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The article is open access:

Pesticide exposure in honey bees results in increased levels of

the gut pathogen Nosema

Jeffery S. Pettis, Dennis vanEngelsdorp, phine and Galen Dively

Naturwissenschaften (2012) 99:153–158

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<http://www.springerlink.com/content/p1027164r403288u/fulltext.pdf>

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<http://www.springerlink.com/content/p1027164r403288u/fulltext.html>

Global pollinator declines have been attributed to habitat destruction,

pesticide use, and climate change or some combination of these factors,

and managed honey bees, Apis mellifera, are part of worldwide pollinator

declines. Here we exposed honey bee colonies during three brood

generations to sub-lethal doses of a widely used pesticide,

imidacloprid, and then subsequently challenged newly emerged bees with

the gut parasite, Nosema spp. The pesticide dosages used were below

levels demonstrated to cause effects on longevity or foraging in adult

honey bees. Nosema infections increased significantly in the bees from

pesticide-treated hives when compared to bees from control hives

demonstrating an indirect effect of pesticides on pathogen growth in

honey bees. We clearly demonstrate an increase in pathogen growth within

individual bees reared in colonies exposed to one of the most widely

used pesticides worldwide, imidacloprid, at below levels considered

harmful to bees. The finding that individual bees with undetectable

levels of the target pesticide, after being reared in a sub-lethal

pesticide environment within the colony, had higher Nosema is

significant. Interactions between pesticides and pathogens could be a

major contributor to increased mortality of honey bee colonies,

including colony collapse disorder, and other pollinator declines worldwide.

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