Scientists yesterday identified a virus as one of the likely causes of the recent wave of honeybee colony collapses across the country.
The study, co-authored by researchers at Pennsylvania State University, Columbia University, the U.S. Department of Agriculture and several other institutions, suggests that the Israeli acute paralysis virus (IAPV) helps trigger the mysterious condition known as colony collapse disorder, which destroyed about 23 percent of U.S. beehives last winter. The paper is being published today in the journal Science.
Beekeepers, scientists and public officials have been searching for the cause of the disorder, which surfaced in 2004 and was formally recognized last year. Unlike other diseases that strike hives, the collapse disorder leaves a colony without most of its worker bees despite the presence of plentiful food, a queen and other adult bees. It has devastated an industry that produces honey and pollinates lucrative crops such as almonds, oranges and apples.
The scientists who authored the paper emphasized that they have begun to solve the puzzle but have yet to determine exactly what causes a colony's abrupt decline.
"This is a major finding," said Columbia University professor W. Ian Lipkin, an epidemiologist who normally focuses on human diseases. "What we have at present is a marker. We do not think IAPV alone is causing this disease."
Israeli scientists had already identified a lethal strain of the virus in their country. Lipkin said in a telephone interview that U.S. researchers had found a closely related virus that "may be somewhat muted," or less virulent. Other factors, such as the varroa mite, a well-known parasite that attacks bees, may be weakening bees' immune systems and making them more vulnerable to the virus.
Using the recently mapped honeybee genome, American scientists were able to identify genetic material from viruses and other pathogens in bees collected over the past three years from healthy and sick colonies across the country. They found evidence of the virus in 25 of 30 affected colonies, but just one of 21 unaffected hives.