WASHINGTON — Mid-Columbia farmers depend on honeybees to pollinate the apples, sweet cherries, onions and other fruits and vegetables that represent their livelihoods.
But those honeybees are the victim of one of the most perplexing environmental mysteries of recent years: Why are they dying, and what can be done to stop a catastrophic agricultural disaster with far-reaching economic and environmental consequences in the United States and beyond?
Scientists dont have a definitive answer. But a U.S. Department of Agriculture and Environmental Protection Agency report issued Thursday suggests a complex mix of problems contributing to honeybee colony declines, which first emerged in 2006.
Contributors include parasites and disease, genetics, poor nutrition and pesticide exposure, as well as farming practices that dont give bees a pesticide-free buffer zone to forage in heavily developed agricultural regions.
Modern farming practices are leaving very little room for bees and other pollinators at this moment, Sonny Ramaswamy, director of the USDAs National Institute of Food and Agriculture, said in a conference call explaining the report.
The report warns that even with intensive research to understand the cause of honeybee colony losses in the United States, losses continue to be high and could pose a serious threat to meeting the pollination demands for some commercial crops. Growers in California have had trouble pollinating almond trees in the winter, for example, and blueberry farmers in Maine face similar pressures.
An unofficial survey by beekeepers in Washington suggests a 40 to 50 percent colony loss for a variety of reasons, said Tim Lawrence, director of the Island County Washington State University Extension.
With about 300 crops, Washington is one of the nations most diverse agricultural states. The state is No. 1 in the nation when it comes to growing apples and sweet cherries, which bees pollinate at this time of year. Apples are Washingtons most valuable crop, representing $1.8 billion in 2011.
Honeybees are by far the most convenient pollinator, Lawrence said.
The report cited the parasitic Varroa mite, which preys on bees and introduces viruses and bacteria, as the major factor underlying honeybee colony loss in the U.S. and other countries. There is widespread resistance to the chemicals beekeepers use to control mites within the hive.
Beekeepers are limiting their ability to control mites by feeding bees pollen or sugar syrup year-round to strengthen them, Lawrence said. That means there is always brood the eggs, larvae and pupae that will become full-grown bees. Recent research has shown that broodless periods in the hive are the only times when beekeepers should use chemicals to control the mites.
Wax in the combs absorbs chemicals, including those the beekeepers use to control the mites and pesticides from the fields, Lawrence said. Bees use chemicals to communicate, so throwing chemicals at colonies has an impact.
Many commercial beekeepers are using chemicals that arent registered for use in colonies, Lawrence said.
You cant make money off of dead bees, he said.
Some beekeepers have taken to changing combs to try to improve bee health. Lawrence said thats a good routine practice, but the wax is constantly being contaminated.
Bee colony collapse touches on all aspects of American agriculture. The USDA estimates that one-third of all food and beverages are made possible by pollination, mainly by honeybees. Pollination contributes to an estimated $20 billion to $30 billion in U.S. agricultural production each year.
Hector Castro, the Washington State Department of Agricultures communications director, said, We are keenly aware of some of the health issues and stresses facing honeybees and hives and beekeepers as they struggle to keep their colonies healthy.
The state recently received a petition from a beekeeper group in Thurston County to restrict pesticides known as neonicotinoids and require a license for their use, Castro said. The agriculture department has not yet decided if it will go through a rule-making process on neonicotinoids.
While neonicotinoids have recently taken the limelight, Lawrence said there isnt enough information to link them as a major or primary cause of colony collapse.
But some researchers and beekeepers fear Thursdays report didnt emphasize neonicotinoids enough.
I think it really downplays the effects of pesticides, said Jeff Miller of the Center for Biological Diversity, an Arizona-based nonprofit group, which has sued unsuccessfully so far to force the EPA to consider the effect of pesticides on endangered species when it authorizes or reauthorizes pesticide use.
The EPA wants to get the science behind colony collapse right and not just because we adhere to science in some kind of an abstract way, said Jim Jones, acting assistant administrator of the EPAs Office of Chemical Safety and Pollution Prevention.
Officials in the European Union this week voted to move toward a ban on three popular pesticides in an effort to restore honeybee populations. In the United States, environmentalists and beekeepers have sued the EPA to stop the use of some of the pesticides.
Part of the problem is the nations complex agricultural system, Lawrence said. Bees are transported nationwide to pollinate. And while beekeepers are good at managing bees, things that have worked in the past arent working now.
He recalls standing on a hill in California, where the almond industry creates a demand for bees, and being able to see 84,000 hives.
That is feedlot beekeeping, said Lawrence, a former commercial beekeeper, who continues to keep some colonies. Its a very unnatural system.
Idaho-based beekeeper Zach Browning, who co-owns one of the countrys largest honey producers, said his 2012 colony losses were double what they were in 2011. He lost bees to drought, pesticides and hives that didnt have enough to eat.
Were on the brink. I dont know that weve crossed that threshold yet, but were certainly getting there very fast, said Browning, who joined USDA and EPA officials in announcing the report.
Click here to view the report.