WASHINGTON — It’s one of the most perplexing environmental mysteries of recent years: Why are honeybees 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 don’t yet 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 don’t 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 USDA’s 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.
“We’re on the brink. I don’t know that we’ve crossed that threshold yet, but we’re certainly getting there very fast,” said Idaho-based beekeeper Zach Browning, who joined USDA and EPA officials in announcing the report.
His 2012 colony losses were double what they were in 2011, said Browning, who co-owns one of the country’s largest honey producers. The producer lost bees to drought, pesticides and hives that didn’t have enough to eat, he said.
But it’s pesticide use that has drawn the most interest in recent months, and some researchers and beekeepers fear Thursday’s report didn’t emphasize enough the possible effects of the widespread use of a class of pesticides known as neonicotinoids.
“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.
“There’s some pretty strong links now, especially to the neonicotinoid pesticides and colony collapse disorder,” Miller said in an interview. “There’s some science showing that pesticide impacts may be increasing vulnerability to disease.”
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.
Recent research done by Christian Krupke of Indiana’s Purdue University suggests that dust raised when corn seeds are planted may be a major contributor to some bee declines. Those seeds are coated with pesticides, and farmers use air pressure to move the seeds from a spreader to the soil. The dust that’s added to help move the seeds gets blown out of the machine. It also lands on nearby plants that might be fodder for honeybees.
Asked Thursday whether they thought they’d underemphasized the role of pesticides in their report, officials with the EPA said they want 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 EPA’s Office of Chemical Safety and Pollution Prevention.
“There are non-trivial costs to society if we get this wrong,” Jones said. “These are products that not only provide meaningful benefits to the farms that use them, but they then generate benefit to consumers as well for affordable foods in the United States. And they also are compounds that in a general matter for human health and the environment are preferable to the alternatives.”
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.
A consortium will study the problem this year with the hopes of putting in place measures to help reduce bee deaths next growing season, said Laurie Davies Adams, executive director of the San Francisco-based Pollinator Partnership, which is overseeing the project.
Farmers, beekeepers, pesticide manufacturers, corn growers, government researchers and academics will study this summer ways to address the corn dust problem by changing the lubricant used in the machinery, as well as trying to improve foraging conditions for bees at the same time the pesticides are applied.
“It’s not in anybody’s interest to kill bees,” she said. “It just isn’t.”
