Researchers have identified a virus that may be at least partially to blame for the dramatic disappearances of some honeybees in the United States recently. In a study published online today in Science, scientists report that they've found Israeli acute paralysis virus (IAPV) in many of the US bee colonies that have been suffering from colony collapse disorder (CCD) and a virtual absence of the virus in healthy colonies.

A research team from Pennsylvania State and Columbia Universities and elsewhere used the latest whiz-bang high throughput pyrosequencing techniques to identify a gaggle of fungi, parasites, bacteria, viruses and other microorganisms inhabiting honeybees. They found IAPV, which had not previously been detected in the US, in all of the samples from colonies afflicted with CCD and in only one healthy colony. IAPV was first reported in Israel in 2004, and caused paralysis and the eventual death of bees there. Though these symptoms have not yet been seen in CCD episodes in the US, IAPV could be impacting bees in this country differently through co-infection, strain variations, or by acting in concert with other honeybee stressors.

As this was only a correlation, the authors of the study pointed out that several factors, including introduced mites that suppress bee immune systems, drought-induced nutritional deficiencies, pesticides, and the stress of traveling from flowering crop to flowering crop at the behest of their migratory keepers, may also be contributing to CCD.

About 23 percent of US beekeepers were hit with CCD over last winter, some losing up to 90 percent of their bees. CCD has baffled scientists since it was first reported in 2004. Colonies hit with CCD simply and inexplicably lose adult bees. No dead bees are found in the immediate vicinity of the hives as in other bee diseases.

The researchers also found IAPV in bees imported from Australia and in royal jelly imported from China, raising the concern that continued import from these countries could worsen the problem.

The study points to future research where healthy colonies are infected with IAPV to see if this results in CCD.

For now, the researchers said, engineering a strain of bee that is resistant to IAPV would be a good first step, even though the virus may not be the only cause of CCD.