A new federal report blames a combination of problems for a mysterious and dramatic disappearance of U.S. honeybees since 2006.
The intertwined factors cited include a parasitic mite, multiple viruses, bacteria, poor nutrition, genetics, habitat loss and pesticides.
The multiple causes make it harder to do something about what's called colony collapse disorder, experts say. The disorder has caused as much as one-third of the nation's bees to just disappear each winter since 2006.
Bees, especially honeybees, are needed to pollinate crops.
The federal report, issued Thursday by the Agriculture Department and the Environmental Protection Agency, said the biggest culprit is the parasitic mite varroa destructor, calling it "the single most detrimental pest of honeybees."
The problem has also hit bee colonies in Europe, where regulators are considering a ban on a type of pesticides known as neonicotinoids that some environmental groups blame for the bee collapse. The U.S. report cites pesticides, but near the bottom of the list of factors.
Dave Gaulson of the University of Stirling in Scotland, who conducted a study last year that implicated the chemical, said he can't disagree with the overall conclusions of the U.S. government report. However, he said it could have emphasized pesticides more.
The environmental group, Pesticide Action Network North America blasted the federal government for not following Europe's lead in looking at a ban of certain pesticides. -- AP