Bees exposed to common pesticide can't find flowers

http://www.cbsnews.com/news/bees-exposed-to-common-pesticide-cant-find-flowers/

By Michael Casey CBS News June 18, 2015

Bees sniff out the aroma of flowers to identify ones they know have nectar. It's a crucial part of the pollination processes. But new research suggests that a controversial pesticide used widely in agriculture could interfere with it.

In the United States in the past year, beekeepers have lost 40 percent of their colonies. A study published in Nature Thursday offers the latest evidence suggesting that neonicotinoid pesticides may be behind the demise.

"Honeybees need to learn to associate nectar reward with floral odor. One of the main reasons why flowers produce odor is so that this odor can be learned by pollinators and used to repeatedly visit the same flower species," Chinese Academy of Science's Ken Tan, who led the study, told CBS News in an email interview.

"Without this repeat visitation, pollination does not occur. We showed that a neonicotinoid pesticide, at sublethal doses, harms this odor memory formation. We also tested the effects of the pesticide, imidacloprid, on bees exposed as adults and as young larvae. Both types of pesticide exposure reduced the ability of bees to remember odors associated with nectar."

Since 2006, bees have been hit by a devastating condition known as colony collapse disorder or CCD. The mysterious disorder causes honeybees to disappear from their hives, and their bodies are rarely found. Beekeepers across the United States have reported losing 40 to 50 percent of their hives to the condition, raising concern how this might affect the nation's food supply.

Scientists have found it difficult to pinpoint the cause, which threatens the nation's $2.75 million of managed colonies and could one day impact the nation's food supply since bees are crucial to pollination. The economic value of bee pollination services ranges from $10 billion to $15 billion.

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The Environmental Protection Agency has also proposed pesticide-free zones for bees.

Meanwhile, the evidence continues to mount showing bees are affected in several ways when exposed to neonicotinoids.

One study out earlier this year in Nature found that buff-tailed bumblebees and honeybees seem to become addicted to the pesticide, which contain nicotine, much as a smoker becomes addicted to cigarettes. Another study in Nature found that some bees don't grow as well in pesticide-laced fields, and that others won't return to nesting sites in those fields.

But the pesticides didn't seem to impact the colony strength of honeybees, the most common species used in commercial pollination.

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