John Schwartz of the New York Times tells us that Report Says Fewer Bees Perished Over the Winter, But the Reason Is a Mystery, according to a study conducted by the Department of Agriculture and the Bee Informed Partnership.
The new survey, published on Thursday, found that the loss of managed honeybee colonies from all causes dropped to 23.2 percent nationwide over the winter that just ended, down from 30.5 percent the year before. Losses reported by some individual beekeepers were even higher. Colony losses reached a peak of 36 percent in 2007 to 2008. ...
While much attention has been paid to colony collapse disorder, in which masses of bees disappear from hives, that phenomenon has not been encountered in the field in the past three years, Dr. vanEngelsdorp said. Instead, what has emerged is a complex set of pressures on managed and wild bee populations that includes disease, a parasite known as the varroa mite, pesticides, extreme weather and poor nutrition tied to a loss of forage plants. ...
Treating colonies for the varroa mite, an Asian parasite that first reached the United States in 1987, seems to have the most direct effect on stemming losses, Dr. vanEngelsdorp said. “The beekeepers that are treating for varroa mites lose significantly fewer colonies than beekeepers that are not treating colonies for varroa mites,” and those who treat them four or five times a year do better than those who treat them only once or twice, he said.
John Schwart reports that one controversy remaining unsettled is the impact of a class of pesticides known a neonicotinoids which some research has shown to have especially detrimental impacts on bees. One paper published his month in the Bulletin of Insectology found that 6 of 12 healthy bee colonies exposed to the pesticide died.
Bayer, one of the leading manufacturers of neonicotinoid pesticides, has protested that the scientists exposed these bees to too test doses higher than they would receive in natural settings adjacent to farms using the chemical. Scientists challenged Bayer to specify what dosages Bayer thinks bees will be exposed to in those settings.
While it is slightly encouraging that the rate of catastrophic loss of our bees has fallen from 30.5% the New York Times lead paragraph seems oddly optimistic. This is still a serious problem we need to be highly concerned about. I look forward to reading what FishoutofWater, and occupystephanie's have to say about this report. They seem to be some our site's leading experts on bees and other pollinators.
6:01 PM PT:
Thanks to Simian for providing this link to an article to the Harvard study reported by Fishoutofwater on March 9. It may be the second study referred to at the end of this NYT that Bayer challenged I have to check the researchers. These authors and Fishoutofwater report a much stronger finding implicating the neonicotinoid pesticides than reported by the New York Times article, which does not even mention the European research. Thanks Simian.
Neonicotinoid Insecticide Impairs Winterization Leading to Bee Colony Collapse: Harvard Study
FishOutofWater
The mystery of why honey bees leave their colonies in the middle of winter to die in the cold has not been completely solved but a carefully controlled study by Harvard university researchers has found the smoking gun - neonicotinoid insecticides. In spring and summer honey bees go through rapid cycles of reproduction and death. As winter approaches, these cycles slow down as bees respond to dropping temperatures. The Harvard researchers found that something goes awry with this winterization process when bees are affected by low, sublethal doses of neonicotinoid insecticides. Insecticide affected bees left their colonies and died in the cold of winter.
We found honey bees in both control and neonicotinoid treated groups progressed almost identically through the summer and fall seasons and observed no acute morbidity or mortality in either group until the end of winter. Bees from six of the twelve neonicotinoid treated colonies had abandoned their hives, and were eventually dead with symptoms resembling CCD. However, we observed a complete opposite phenomenon in the control colonies in which instead of abandonment, they were repopulated quickly with new emerging bees. Only one of the six control colonies was lost due to Nosema like infection. ...
"We demonstrated that neonicotinoids are highly likely to be responsible for triggering 'colony collapse disorder' in honeybee hives that were healthy prior to the arrival of winter," said Chensheng Lu, an expert on environmental exposure biology at Harvard School of Public Health and who led the work.
6:30 PM PT: It looks like the "controversial" study on the neonicotinoid pesticides mentioned at the bottom of this NYT article is the one Fishoutofwater posted about from the Harvard researchers last week. Bayer, a leaders manufacterer of neonicontinnoid pesticides challenged the Harvard study by saying the test exposure were 10 times what the bees would have received in "nature." The Harvard scientist counter-challenge Bayer to specify what they are talking about and what "dosage" level they suggest.
I am already up to my fair use limit so I'm sorry I can not post these paragraphs, so please go to the NYT times article and Fish's post to read about this fascination controversy.