Cause of Colony Collapse Disorder May Have Been Cracked

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A report published in the Wednesday edition of online science journal PLoS One purports to find a major cause for a pressing biological and environmental question that has perplexed scientists since 2006: Colony collapse disorder (CCD), which has reduced bee populations in the United States by between twenty and forty percent, per the New York Times.

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CCD presents an alarming problem because of bees’ importance to the ecosystem: According to the USDA, between a quarter and a third of human nutrition comes from plants pollinated by bees. Further mass bee dieoffs pose a not insignificant threat to the world’s food supply.

According to the PLoS One report, which was produced by a collaboration between Montana bee experts and military researchers, colony collapse disorder may be caused by a fungus and a virus working in tandem.

The fungus, N. ceranae, and the virus, invertebrate iridescent virus (IIV), were both found in every collapsed bee colony studied: While neither is devastating by itself, in tandem, they are “100 percent fatal.”


“It’s chicken and egg in a sense — we don’t know which came first,” Dr. Bromenshenk said of the virus-fungus combo — nor is it clear, he added, whether one malady weakens the bees enough to be finished off by the second, or whether they somehow compound the other’s destructive power. “They’re co-factors, that’s all we can say at the moment,” he said. “They’re both present in all these collapsed colonies.”

If the researchers’ findings hold true, the next, even trickier step will be management to keep the likelihood of co-infection in check. While the virus can’t currently be treated without killing off the bees, the fungal N. ceranae can. From the journal article:

We suggest that for beekeepers suffering from colony losses, disruption of the potential IIV/Nosema relationship using treatments that are available to control Nosema species may be one option to help reduce honey bee mortality. Again, whether this identified bee IIV and its potential interaction with Nosema species is the cause or marker of CCD, is unknown, but our results clearly suggest that further research in this area is urgently required.

(via NYTimes | PLoS One journal article. Title pic via Shutterstock.)

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