Bee Experts Look To Pesticides, Diseases, Stress

WASHINGTON — Scientists and worried beekeepers agreed Tuesday to explore pesticide poisoning, diseases, parasites and management practices in an effort to find out why billions of honeybees have died in the past six months.

Following two days of brainstorming, about 60 bee experts agreed to recommend an urgent research agenda aimed at sorting out the causes of "colony collapse disorder," an unusual die-off that became apparent last year.

There was little interest in the 60 workshop participants in what one described as "the other stuff — power lines, cell phones, Martians." German scientists reported last week that microwave signals used by cell phones appear to interfere with bees' ability to navigate.

The conference was set up after a House agriculture subcommittee criticized the department for not responding to the die-off quickly enough. "We should have been doing this two months ago," said Troy Fore of Jessup, Ga., executive secretary of the American Beekeeping Federation.

The colony collapse phenomenon, which first became apparent in Florida and was quickly identified in Pennsylvania, Montana and California, occurs when worker bees leave the hive and don't return. Queens and "brood" of bee larvae remain inside until they die also.

Fore and other bee industry figures and scientists said the colony collapse phenomenon resembles many of the ways bees have always died, but for one notable exception: The empty hive is shunned by other bees and insect scavengers.

"I was very much a skeptic about this thing when I first heard of it," said Danny Weaver, a Novosota, Texas, bee breeder who is president of Fore's group.

He said his skepticism vanished when he obtained honeycomb from a collapsed hive and put it in an area heavily populated with bees and bee parasites, including wax moths.

"Nothing would go near it," Weaver said. "Ordinarily, other bees would be robbing that honey, moths would be all over it. But nothing."

In addition to the honey they produce, bees provide billions of dollars a year in pollination services for American agriculture, and a National Academy of Science committee warned a few months ago that their role in this area has been woefully neglected. In the California almond industry alone, 1.3 million colonies — half of all the bees in America — are required for pollination each year.

Scientists at the conference had many hypotheses for the disorder, but no answers.

Spreading infestation by mites that invaded the U.S. bee industry in the 1980s could have weakened the insects and left them susceptible to infections they have resisted for ages.

Pesticides, especially a relatively new class of chemicals called neonicotinoids, could have sub-lethal effects that do the same thing. These chemicals are now America's most widely used pesticides, from crops to homes to golf courses, and they act by disrupting the insects' nervous systems. This might be related to the failure of workers bees to return to hives, as if they have become disoriented.

"It's too strong a coincidence to ignore," said Maryann Frazier, a Pennsylvania State University entomologist.

She said bee samples have been sent to an Environmental Protection Agency lab in North Carolina to be analyzed for more than 200 pesticides.

Still another theory is that mites could be spreading a disease-causing virus among bees.

Bee management practices also must be investigated, scientists said.

Jerry Hayes, a Florida department of Agriculture entomologist, said bees are given a variety of antibiotics to ward off infections, and this may be interfering with natural bacteria in their guts that help ferment pollen to produce a hive food.

"We may need probiotics for bees," one scientist said.

One experiment in countering the effects of the disorder, still under way, involved treating hives with acids or irradiating them.

Preliminary results indicate the disease is more likely to recur in hives that have not been treated, said Dennis vanEngelsdorp, another Penn State scientist.