Washington ? Scientific sleuths have a new suspect for a mysterious affliction that has killed off honeybees by the billions: a virus previously unknown in the United States.

The scientists report using a novel genetic technique and old-fashioned statistics to identify Israeli acute paralysis virus as the latest potential culprit in the widespread deaths of worker bees, a phenomenon known as colony collapse disorder.

Next up are attempts to infect honeybees with the virus to see if it indeed is a killer.

“At least we have a lead now we can begin to follow. We can use it as a marker and we can use it to investigate whether it does in fact cause disease,” said Dr. W. Ian Lipkin, a Columbia University epidemiologist and co-author of the study.

Experts stressed that parasitic mites, pesticides and poor nutrition all remain suspects, as does the stress of travel. Beekeepers shuffle bees around the nation so the bees can pollinate crops as they come into bloom, contributing about $15 billion a year to U.S. agriculture.