Another study adds to the buzz that a certain class of pesticides, called neonicotinoids, may be behind the bee-killing colony collapse disorder. But the findings have stirred up a hornet's nest of objections from the pesticides' manufacturer, Bayer.
Harvard University biologist Chensheng Lu found a correlation between an imidacloprid-contaminated diet and one of the symptoms of colony collapse disorder.
Neonicotinoids are pesticides chemically similar to nicotine found in tobacco. The pesticides, such as imidacloprid, clothianidin and thiamethoxam, are both sprayed on crops and used to treat seeds prior to planting. Discovery News reported on a study that suggested pesticide-contaminated residue blown off from treated seeds during planting could be harming bees.
Some entomologists and conservationists also worry the chemicals find their way into the nectar and pollen bees feed on and products subsequently made from plants treated with neonicotinoids, such as corn.
Commercially available high-fructose corn syrup may contain residues of imidacloprid, contends Lu.
Lu replicated commercial beekeeping procedures by feeding bees high-fructose corn syrup, an enzymatically treated super-sweet sugar used to give bees an energy boost. He spiked some of the syrup with imidacloprid. Many of the bees that fed on the neonicotinoid-tainted syrup left their hives in the middle of winter, a deadly mistake associated with colony collapse disorder.
"I believe one reason that commercial beekeepers are experiencing the most severe colony collapse disorder is because of the link between high-fructose corn syrup and neonicotinoids," Lu said in Wired.
But Bayer, a German chemical manufacturer that produces neonicotinoids, believes Lu used pesticide concentrations above what would be found in the field. The company states that imidacloprid residues have never been found in high-fructose corn syrup. They also contend that the imidacloprid Lu used has largely been replaced by another type of neonicotinoids.
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Charles Benbrook of The Organic Center, an organic food research consultancy, told Wired that Lu would have gotten the same results regardless of the type of neonicotinoid the bees ate. Lu's study will be published in the Bulletin of Insectology in June.
Photo: Western honeybee sitting on a flower. Credit: Wolfgang Hägele, Wikimedia Commons.