研究員將這些問題稱之為「蜂群崩壞症候群」（colony collapse disorder, CCD），綜合特徵就是一個蜂群突然之間完全崩解。如果在某個蜂群中即便只有有少數或任何蜜蜂死亡，對養蜂人和研究員來說都是相當令人沮喪的。
Honeybees are vanishing at alarming rates across the United States and researchers are struggling to pinpoint the exact cause of the decline, experts told a Congressional panel Thursday.
U.S. beekeepers have lost a record 36 percent of their colonies this year, about twice the amount lost during a typical winter, and they warn that the mysterious disorder afflicting the bees could have serious environmental and economic consequences.
"This is more than just a beekeeping problem," said David Mendes, vice president of the American Beekeeping Federation. "There is something in the environment that is making our bees sick."
It is not just the $15 billion honeybee industry that is at risk, the House Agriculture Subcommittee on Horticulture and Organic Agriculture was told. A third of U.S. crops, including most fruits and vegetables, rely on the commercial bees for pollination.
Food prices, already rising due to high fuel prices and weeks of Midwest floods, are likely to rise even higher with the scarcity of healthy bees.
"Bees are as important to our crops as the water and sunshine," said North Carolina farmer Robert Edwards, who said the lack of bees has forced him to cut his cucumber crop in half. "No bees, no crops."
Researchers have labeled the problem colony collapse disorder, CCD, a syndrome characterized by the sudden and complete collapse of a bee colony. Frustratingly for beekeepers and researchers, few if any dead bees are found at the colony.
CCD was first identified in late 2006, but efforts to unravel the mystery have provided no definitive answers to date. The latest survey provides evidence it is getting worse in the United States - the 36 percent losses reported this year are up from 31 percent a year ago.
"We have had rough years from time to time with higher than usual losses, and in history there have been a few epidemics in the bee world," said Steve Godlin, a California commercial beekeeper. "But nothing has been on the levels we are facing now."
Researchers are studying possible causes including viruses, parasites, environmental and transport stresses, poor nutrition and pesticides.All of these factors may be contributing, Mendes said, but a growing number of beekeepers believe pesticides are the main culprit.
Relatively new nicotine-based pesticides are known to affect the immune and nervous systems of insects, disrupting feeding behavior and causing memory loss.
"That is what we are seeing in our hives," Mendes told members of the subcommittee. "The frustrating thing is the cause and effect seem separate.
They don't come apart right away." The pesticides do not kill the adult bees, he explained, but compromise their immune systems. The adult bees also carry the chemicals back to the hive, where they contaminate pollen fed to developing bees.
"You could be exposed in March or April and your bees look fine," Mendes said. "But come October ?they are coming apart."
Mendes is one of several beekeepers who has collected samples of bees, comb, pollen and honey from his hives for testing, gathering the material each time each hive was moved during a 10 month period. The samples tested showed much higher levels of pesticides than expected, he said.
"Of the 18 hives that began this study in March 2007, only four of these hives were still alive 10 months later," Mendes told the panel. "Of these four hives only one was of sufficient strength to pollinate almonds in California in February."
Germany last month banned a nicotine-based pesticide due to concern the chemical was causing CCD, said Mendes, but U.S. regulators lack the data to make such a decision.
Flanagan urged the lawmakers to heed warnings sounded by Mendes and other beekeepers and to give their anecdotal evidence greater weight.
Maryann Frazier, a researcher at Pennsylvania State University, agreed pesticides are likely to be at least one factor contributing to CCD.
"In the past, pesticide poisoning of honey bees has been associated with lethal exposure and the obvious symptom of a pile of dead bees in front of the hive," she told the subcommittee. "We are becoming increasingly concerned that pesticides may affect bees at sublethal levels, not killing them outright, but rather impairing their behaviors and their abilities to fight off infections."
A top official with the U.S. Department of Agriculture, USDA, research division cautioned that more research is needed before pesticides can be blamed for the disorder.
Research suggests CCD is "caused by an interaction of multiple factors stressing the colony rather than a single cause" and has yet to confirm an association with pesticides, said Edward Knipling, administrator of the U.S. Department of Agriculture's research division.
He said the Agricultural Research Service spent some $6 million on honeybee research last year and has requested an additional $780,000 for fiscal year 2009.
Critics contend that sum does not reflect the urgency of the problem.
The worry about colony collapse disorder has also prompted several companies to funnel money into researching the issue. Ice cream giant Häagen-Dazs, for example, has launched a "Help the Honey Bees" campaign and pledged $250,000 to fund pollinator research.
The head of Burt's Bees, which manufactures personal care products from natural ingredients, also appeared at the hearing to urge for more help from the federal government.
The company has started a public service campaign to inform consumers about CCD and pledged to donate some of its profits to fund bee research.
Mendes urged USDA officials to devise a comprehensive program to sample hives across the nation and to test them for pesticides, arguing it is unfair and unrealistic to expect beekeepers to shoulder the financial burdens of researching the disorder.