Virus may play role in bee decline

WASHINGTON – Scientists Thursday identified a virus as one of the probable causes of the recent wave of honeybee colony collapses across the country.

The study, co-authored by researchers at Penn State University, Columbia University, the U.S. Department of Agriculture and several other institutions, suggests that the Israeli acute paralysis virus 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 team of scientists who authored the paper emphasized that they have begun to unlock 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 usually 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 previously 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 their immune systems and making them more vulnerable to the virus.

Penn State entomologist Diana Cox-Foster, the paper’s lead author, said she and her colleagues found no evidence that cell phone signals were affecting the bees, as some have speculated. Pesticides on the crops that bees pollinate, which many bee keepers suspect could be harming them, “could be helping to stress the bees, or acting as a potential trigger,” she added.

The researchers said Australian honeybees imported to the United States in recent years may be the source of the virus. Australia does not have the varroa mite, which may explain why it has not experienced the disorder. Other countries, such as Israel, Austria and Canada, have had cases of colony collapse, though not on the same scale as the United States.

It is unclear whether U.S. authorities will bar future imports of Australian honeybees in light of the new research.