WASHINGTON — Researchers from the U.S. Department of Agriculture and other agencies still don't know why worker bees are vanishing from their colonies in drastic numbers, but they have a hunch that the problem could be related to a parasite spreading a virus among the six-legged insects.

The team presented its latest findings of colony collapse disorder to a House subcommittee on Thursday as farmers told lawmakers they are worried that the disorder could devastate crop supplies if left unchecked. Several crops, including blueberries in South Georgia to citrus in North Florida, depend on bee pollination to grow.

Mike Groll/AP (ENLARGE)

Beekeepers began reporting unusual bee losses in October 2006. Surveys indicate the situation has not improved.

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Edward Knipling, administrator of the agriculture department's scientific research agency, said the Israeli acute paralysis virus may be associated with colony collapse. And the varroa mite, a parasite, may be spreading the virus to other bees.

Knipling added the finding deserves further research.

"Even though research to date has not produced a definitive finding on the cause of or solution to the CCD problem, the research is making important progress toward our understanding of the disorder," Knipling told the House Horticulture and Organic Agriculture subcommittee.

Beekeepers began reporting unusual losses in October 2006. Surveys indicate the situation has not improved, he said. Overall bee colony losses are about twice the percentage of losses sustained during a typical winter. So far in 2008, beekeepers have seen a 36 percent loss, compared to a 31 percent loss in 2007.

Researchers say that colony collapse could be a combination of factors. They are also considering pathogens, poor nutrition of bees and the stress many of the insects undergo when hauled from one field to the next to pollinate farmers' crops.

Maryann Frazier, senior extension associate with Pennsylvania State University, said the impact of pesticides also warrants more research. Pesticides used by growers to control insects, disease and weeds may not be killing bees outright but may impair their behaviors and their ability to fight off infection.

"While in the long run honey bees will mostly likely survive, our beekeepers may not," Frazier told the subcommittee. "In an effort to keep their bees alive and their businesses afloat, and to meet critical pollination contracts, they have pushed themselves to the limits financially, emotionally and physically during the past 18 months."

Frazier urged the subcommittee to budget more funding for colony collapse disorder research. There's still much to study — for instance, about 2,000 samples of pesticides that still need to be analyzed, a $200,000 project, she said.

Robert Dowe Edwards, a farmer from Whitakers, N.C., said his family farm was forced to cut its acreage of cucumbers in half. Edwards blames the reduction on a combination of things, including higher gas prices and labor costs. But the problem with honeybees has irritated the situation, he said.

"The simple fact is, no honeybees, no cucumbers," he said.

Democratic Rep. Dennis Cardoza of California, the subcommittee chairman, assured farmers and scientists that more funding could be coming soon. Cardoza noted that the recently passed Farm Bill includes disaster assistance for honey and honey bee losses. And the president's fiscal year 2009 budget proposal requests $780,000 in new funding to enhance support for honey bee health and colony collapse disorder research.