Fungus fingered in US honeybee wipeout

Possible cause of Colony Collapse Disorder?

By Lester Haines • Get more from this author

Posted in Biology, 27th April 2007 14:52 GMT

Scientists may have fingered a possible major contributory cause to Colony Collapse Disorder (CCD) - the hitherto unexplained disappearance of millions of honeybees in Europe, the US and seemingly Taiwan.

According to the Los Angeles Times, researchers have identified the single-celled fungus Nosema ceranae in dead bees from hives in Merced County, California. Other teams have similarly spotted the fungus in affected hives across the US, as well as two further fungi and 12 viral infections.

Powdered dead bee samples from the California hives were analysed by Dr. Charles Wick of the US Army's Edgewood Chemical Biological Center in Maryland using a "new system of genetic analysis". Wick pinned down several viruses, "including members of a recently identified genus called iflaviruses". These RNA-containing viruses infect the Varroa mite, which in turn lives on honeybees, and scientists speculate they may be fatal to bees.

The center's Evan W. Skowronski was able to offer a more clear-cut explanation for CCD, though. He said: "There was a lot of stuff from Nosema, about 25 per cent of the total. That meant there was more than there was bee RNA. That leads me to believe that the bee died from that particular pathogen."

Skowronski forwarded the tested bee samples to UC San Francisco biochemist Joe DeRisi, who confirmed "evidence of the viruses, along with genetic material from N. ceranae".

The upshot of all this is hope for the US's beekeepers. If N. ceranae is largely responsible for CCD, then scientists hope the antibiotic fumagilli - used to control the closely-related Nosema apis - might do the trick. It would be a timely cure: since last Autumn, 2.4 million commercial colonies across the United States have succumbed to CCD, according to Jerry Hayes of the Florida Department of Agriculture and Consumer Services in Gainesville.

However, DeRisi said at a meeting in Washington DC where 60 bee experts had got together to discuss CCD that the results were "highly preliminary". He warned: "We don't want to give anybody the impression that this thing has been solved."

Entomologist Diana Cox-Foster of Pennsylvania State University explained that Nosema ceranae represents "one of many pathogens" in the bees. She elaborated: "By itself, it is probably not the culprit … but it may be one of the key players." ®

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