NEW YORK, March 30 (UPI) -- A common class of pesticides may be a cause of declining bee colonies worldwide, French and British researchers say.
Both studies focused on the use of pesticides known as neonicotinoids, with results hailed by environmentalists but condemned as inaccurate by makers of the insecticides, The New York Times reported.
French researchers conducting experiments with honeybees say their findings suggest the chemicals affect honeybee brains, making it difficult for them to find their way to their hives.
In Britain, scientists said their study suggests the insecticides keep bumblebees from gathering enough food for their hives to produce new queens.
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The researchers said the studies raise serious concerns about the use of the pesticides.
"I personally would like to see them not being used until more research has been done," David Goulson, a professor at the University of Stirling in Scotland and author of the paper on bees, told the Times. "If it confirms what we've found, then they certainly shouldn't be used when they're going to be fed on by bees."
Other experts were divided about the findings of the two studies.
While environmentalists said the studies support a contention that the insecticides should be banned, a scientist for Bayer CropScience, the leading maker of neonicotinoids, cast doubt on both studies.
In the French study, Bayer's David Fischer said, the honeybees were given far too much neonicotinoid.
"I think they selected an improper dose level," he said.
And while Goulson's study on bumblebees might deserve a "closer look," Fischer said, he argued the weight of evidence points to other causes, such as mites and viruses, as likely culprits in the bee declines.
