Culprit found in billions of bee deaths?

PHILADELPHIA — Researchers have fingered a prime suspect in a disorder causing massive die-offs of honeybees, insects with the monumental job of pollinating $14.6 billion worth of the nation's fruit and vegetable crops annually.

After freezing bees, grinding them up, extracting the DNA and using genetic sequencing to identify every organism present, researchers have settled upon a little-known virus discovered three years ago in Israel.

There, symptoms of a mysterious bee malady came in the form of shivering wings. The bees became paralyzed and died. Thus the name: Israeli acute paralysis virus, or IAPV.

Researchers aren't sure how the virus got to the United States. They don't know how to cure it. Nor do they know if it alone can account for colony collapse disorder, which has killed tens of billions of bees since last fall.

Beekeepers, scientists and public officials have been searching for the cause of the disorder, which surfaced in 2004 and was formally recognized last year.

If scientists can prove the viral infection is helping cause the die-offs, it could clear the way for beekeepers to breed colonies genetically resistant to the disease.

At stake is the food on the nation's tables.

Bees are required to pollinate about one-third of the nation's food crops, including almonds, cherries, blueberries, cranberries, pears, strawberries and pumpkins. California's almonds alone require about 50 percent of all the managed bees in the country; the insects are loaded onto tractor-trailers and trucked west every winter.

"What we have at present is a marker. We do not think IAPV alone is causing this disease," said W. Ian Lipkin, director of the Center for Infection and Immunology at Columbia University's Mailman School of Public Health. "It may require IAPV plus other stressors," such as mites, bacteria or other viruses.

What researchers do know is that IAPV was present in bees that had succumbed to the new disorder and that it was not present in healthy bees.

"The only candidate that was left standing at the end of this rigorous analysis was, in fact, IAPV," said Lipkin, one of a team of researchers led by Pennsylvania State University entomologist Diana Cox-Foster and the U.S. Department of Agriculture's Jeffrey Pettis.

Their findings were published in Thursday's online edition of the journal Science.

Entomologist May Berenbaum, of the University of Illinois, said the findings were "compelling."

But researchers from the U.S. Army's Edgewood Chemical Biological Center in Maryland cautioned that they had unpublished results in which they found the Israeli virus in colonies that did not experience colony collapse disorder.

By now, the ailment has affected 23 percent of commercial colonies, causing losses of 50 to 90 percent of their bees.

Perhaps just as important as ruling in IAPV, researchers were able to rule out other potential causes of the collapsing colonies — from wilder theories, such as disorientation because of cellphone towers, to more probable ones, such as genetically modified crops and pesticides.

Pesticides aren't entirely off the hook, however. Researchers think they could stress a bee, making it more vulnerable to a virus.

The genetic technique involved extracting all the genetic material from the bees and running it through an instrument that can "sequence" — or read the letters and patterns of genetic code — 100 million letters at a time.

The instrument then compares the genetic sequences in the sample with those of known organisms compiled in a massive international database known as GenBank.

With the new equipment, what would have taken years, "we literally do in days," said Michael Egholm, vice president of research and development at 454 Life Sciences, the Connecticut company that did the sequencing.

In effect, identifying what organisms are there and ruling out ones that are not gives biologists a short list of suspects.

"To use the analogy of a crime," Egholm said, "they know who was present at the scene, they just don't know who is the murderer."

Lipkin said this and other new technologies have the potential to revolutionize epidemiology and the investigation of infectious-disease outbreaks among humans.

He said that if similar techniques had been applied to the SARS outbreak in 2003, they could have yielded a viral suspect "in as short as a week."

Typically, "we consider one candidate," he said in a teleconference the researchers held Wednesday. But with the new sequencing, "you simply ask what's present," he said. "We have the opportunity ... to investigate everything that might be associated with a given disease."

Scientists want to try to infect a healthy colony with IAPV to see if the bees die, and they want to learn more about how IAPV works.

Does it merely disorient the bees, making them unable to find their way back to the hive? Or do the bees sicken and then fly off to die, perhaps as a complex protective mechanism for the whole colony?

Researchers also are interested in a group of Israeli bees that may have become resistant to IAPV after incorporating some of the virus' genetic material into their own.

For now, U.S. officials have not shut the nation's doors to two potential avenues of IAPV: "packets" of bees from Australia used to bolster U.S. populations, and royal jelly from China used as a nutrition supplement. For all they know, IAPV arrived some other way.

Material from the Chicago Tribune, The Washington Post and the Los Angeles Times is included in this report.