Small doses of commonly used pesticides seem to have turned honey bees into "picky eaters", which in turn have affected their ability to recruit their nest-mates to otherwise good sources of food, the Science Daily reports.
The experiment was created by a team of biologists at University of California in San Diego, and shed light on one of the main culprits suspected to be behind the recent declines in the honeybee colonies. The result of the study was published in last week's issue of the Journals of Experimental Biology.
Science Daily reports:
"Since 2006, beekeepers in North America and Europe have lost about one-third of their managed bee colonies each year due to "colony collapse disorder.' While the cause is unknown, researchers believe pesticides have contributed to this decline. One group of pesticides, called "neonicotinoids,' has received particular attention from beekeepers and researchers."
The researchers at UC San Diego focused their study on a specific neonicotinoid called "imidacloprid," which has been banned for use on certain crops in some European countries.
"In 2006, it was the sixth most commonly used pesticide in California and is sold for agricultural and home garden use," James Nieh, a professor of Biology at UC San Diego and author of the study, said about their project. "It is known to affect bee learning and memory."
In their study, the scientists harnessed the bees so only their heads could move. By stimulating the bees' antennae with sugar water, they determined what sugar concentrations were rewarding enough to feed on. Using an ascending range of sugar water from 0 to 50 percent, they touched the antennae of each bee to see if it extended its mouthparts. Bees that were treated with imidacloprid were less willing to feed on low concentrations of sugar water than those that were not treated.
Further, they observed that the pesticides affected the bees' communication system because bees communicate with each other by performing waggle dances when they are searching for food.
"Remarkably, bees that fed on the pesticides reduce the number of their waggle dances between fourfold and tenfold," Eiri said. "And in some cases, the affected bees stopped dancing completely."
Eiri and Nieh say their findings not only have implications for how the pesticides are used in bee pollinated crops, but also provide an additional chemical tool that can be used by other researchers studying the neural control of honey bee behavior.
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