Bees' mysterious deaths still stumping scientists
Two and a half years after Pennsylvania beekeepers reported the mysterious disappearance of honeybees, research into the problem is far from finding an explanation.
"This is clearly very complicated. It's also clear that there are lots things killing bees. Everything we look at presents more questions than answers," said Dennis van Engelsdorp, chief bee researcher at the Pennsylvania Department of Agriculture.
Van Engelsdorp compared the cause of the disease, called Colony Collapse Disorder, to the causes of America's No. 1 killer.
"What causes heart disease -- poor diet, genetics, smoking• It could be any one of a whole bunch of things," he said.
Similar questions are prompting researchers to take a fresh look at honeybees and other types of insects that pollinate.
Bees are vital to American agriculture because they pollinate many flowering crops, including almonds, apples and blueberries. Officials estimated that honeybees add $15 billion each year to the value of American agricultural output.
Honeybees, a species from Europe, are the pollinators of choice in American agriculture because they are easy to manage and plentiful. A single colony can contain 20,000 workers, while bumblebee colonies might have only 200.
"There are many species that are threatened by everything from pesticides and herbicides to reduced plant diversity," said Karen Goodell, an Ohio State University ecologist who specializes in the interaction of plants and insects.
Goodell is involved in a project housed at The Wilds, a private, nonprofit conservation center on nearly 10,000 acres of reclaimed mine land near Zanesville, Ohio. The project's focus is on native bees and other insects that have been under threat for decades.
"We are looking at which mix of plants and trees mixes best with the native population of pollinating bees and insects," Goodell said.
About 3,500 species of bees are native to North America.
Goodell is concerned about conditions for honeybees, which are hauled across the country in tractor trailers.
"We have not set up very good environmental conditions for our bees," she said. "If you want to see rapid disease transmission, you go to a day care center; look at male prisoners who use intravenous drugs or look at honeybee colonies, which are cramped and stress bees."
Van Engelsdorp's research indicates that Colony Collapse Disorder is at least partly contagious because its symptoms are more prevalent in the colonies of large commercial beekeepers such as Dave Hackenberg of Lewisburg, Union County, the state's largest commercial beekeeper.
Hackenberg, who hauled thousands of bees to Florida's orange groves this weekend, said he has lost 25 percent of his 2,600 colonies this year.
"I'm OK with that. I had lost more than 40 percent of the colonies by this time last year," he said.
For a generation, honeybees have fallen victim to mites, parasites, sprawl and perhaps the use of pesticides and herbicides. In 2006, the problem worsened as beekeepers reported that Colony Collapse Disorder wiped out 30 percent to 90 percent of their hives. Since then, the annual loss has been about 33 percent, according to government estimates.
The extent of colony losses among commercial beekeepers this winter is not clear because most deaths happen in late January or early February, van Engelsdorp said.
Maryann Frazier, a senior extension associate at Penn State University's entomology department, said researchers remain concerned about the number and combination of pesticides detected in decimated hives.
"We realize it's much more complicated than what we thought a year ago," Frazier said. "From what we know now, it's not something we'll figure out very, very quickly."
Hackenberg and many other beekeepers are convinced chemicals are a major cause of Colony Collapse Disorder.
"It's a bunch of crazy mixtures used for lawn care, shrubbery and golf courses. The American people want a bug-free environment, and we have let the chemical companies run wild," he said.