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A worker honey bee carries a parasitic Varroa mite. Such parasites may be a factor in Colony Collapse Disorder, scientists say . ((Image courtesy of ARS/USDA Scott Bauer))

A honeybee virus new to North America may be linked to a mysterious illness that has struck almost a quarter of the hives in the United States this year, scientists said Thursday.

Writing in an upcoming article in the online edition of the journal Science, a group of U.S. researchers suggest a virus called Israeli Acute Paralysis Virus (IAPV) may be connected to Colony Collapse Disorder, a phenomenon that has struck tens of thousands of honeybees this year.

"The virus appears to be associated with colony collapse disorder," said Pennsylvania State University entomology professor and co-author Diana Cox-Foster during a teleconference on Wednesday.

"Whether it is a causative agent or a very good marker is the next major question we need to address," she said.

Colony Collapse Disorder (CCD) has puzzled scientists and beekeepers alike since it was first discovered in 2004.

Its symptoms are the absence of adult bees with no corpses in the hive, and also the presence of both honey and pollen in the hive.

The ailment became more prominent this spring when some beekeepers in the United States reported losses of most or all of their hives. CCD hit an estimated 23 per cent of all beekeeping operations during the winter of 2006-07, the authors said.

The losses raised concerns throughout agricultural industries, since honeybees also act as an important agent of pollination for many crops.

The scientists used genetic sequencing to trace which viruses, bacteria or parasites were present in the bees affected by the disorder and those unaffected. Only one such virus was always present with CCD — Israeli Acute Paralysis Virus.

The researchers, led by Columbia University's Ian Lipkin, said the identification of IAPV gives them a lead in their investigation, but is likely not the sole cause of the colony collapses. Other issues, such as parasitic mites, nutrition, pesticides and the stress on some bees from frequent apiary moves also could have an impact.

Doug McRory, the provincial apiarist with the Ontario Beekeepers Association, said he had not heard of IAPV before and doubted others in the apicultural industry in Canada had either, but said the lack of knowledge will make it of interest to Canadian beekeepers.

"It will be interesting to see if it's here, and if it is, what effect it's having on our bees," McRory told CBC News.

While many Canadian beekeepers have reported higher-than-usual losses this year, McRory said these losses are not directly attributable to CCD.