WASHINGTON -- Disease-carrying honeybees imported from Australia may be responsible for a mysterious disorder that's decimated bee hives around the country, and federal regulators say they'd consider import restrictions if necessary.
By some estimates, beekeepers in the past several years have lost from a third to half of their hives to what's called colony collapse disorder. Each hive, or colony, can contain as many as 100,000 bees. The bees are disappearing from the hives never to be seen again.
Honeybees pollinate about 100 crops, mostly fruits, vegetables and nuts. By some estimates, more than a third of the food humans consume is pollinated by honeybees.
"Honeybees are important if you want a healthy and nutritious diet," said Robyn Rose, the Agriculture Department's national program manager for honeybee health. "We could live without them but our diet would be pretty bland."
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Scientists are unsure what's causing the problem, though it could involve a combination of factors. Possible culprits include mites, viruses, other diseases, pesticides, habitat loss, stress and even climate change.
The latest suspect, however, is the imported honeybee from Australia.
"A link between the disorder, first reported in the United States in 2006, and honeybee imports from Australia has been suggested," according to a recent notice in the Federal Register by the Agriculture Department's Animal and Plant Health Inspection Service.
The department was seeking comment on a draft report that concluded "zoosanitary" measures or restrictions may be need to reduce the risk that viruses carried by Australian honeybees could reach the U.S.
Such measures might include inspections, quarantines and genetic testing. Agriculture Department officials don't rule out a ban on imports of Australian bees.
"It's a possibility, but not at this point," said Colin Stewart, a senior entomologist at the Agriculture Department.
Honeybees aren't native to North America; they were first brought to the continent by European colonists in the early 1600s.
Officials at the Australian Embassy in Washington insist their bees aren't a threat to U.S. beekeepers, though they admit Australia is facing an invasion of exotic Asian honeybees, which might carry different viruses and mites than those carried by the European honeybees in the U.S.
"It is now widely accepted that this 'suggested' link has been discredited and that there is no single agent responsible for the cause of declining honeybees," the Australian Embassy said in an e-mail.
But beekeeper Eric Olson of Yakima is convinced Australian honeybees are behind the colony collapse outbreak. With nearly 15,000 hives, Olson owns one of the nation's larger beekeeping operations. His hives are trucked across the West, from the almond orchards of California's Central Valley to clover fields in the Dakotas.
For three years in a row, Olson said, he has been losing hives to colony collapse disorder. This past year, he lost 55 percent of his hives.
He thinks federal regulators have been dragging their feet in banning the foreign bees.
"This is more critical to our industry than mad cow was for livestock, and they stopped that," he said. "I'm very unhappy with the government response."
A loss of 30 percent or more of the honeybee hives every year in the U.S. isn't sustainable, said Rose, of the Agriculture Department.
Earlier this month, the department launched a voluntary survey of 350 apiaries in 13 states. Rose said they'll be looking for pests and diseases that haven't been found in the U.S. before.
"We want to prevent the import of bees from countries that have those pests," she said.
Currently, only bees from Australia, New Zealand and Canada can be imported.
Colony collapse disorder hasn't been seen in Australia, and Australian officials say their bees carry the same pathogens found in bees in the U.S.
As for the Asian bees, the embassy said they've been confined to the northern part of the country, and nests and swarms that are eradicated are tested for various mites and parasites. Nothing unusual has been found.
Under new U.S. rules, Australia must certify that the nests of Asian honeybees were at least 100 miles from where the bees packaged for export are raised.
"We are keeping a close eye on it," said the Agriculture Department's Stewart. "They haven't found anything of significance in any of the swarms they have killed."
Many scientists are reluctant to blame colony collapse disorder on a single factor.
"It's a dangerous path to say it's just one thing," said Tim Lawrence, director of the Washington State University Extension in Island County, who used to raise bees. "There will not be a single silver bullet that will solve this."
Beekeeper groups, including those from Washington state and California, have filed a petition with the Agriculture Department requesting that all import permits for Australian and other foreign bees be revoked until it's shown the bees are free of pathogens that could aggravate colony collapse disorder.