From MSNBC:
Scientists investigating a mysterious ailment that killed many of the nation’s honeybees are concentrating on pesticides and a new pathogen as possible culprits, and some beekeepers are already trying to keep their colonies away from pesticide-exposed fields. After months of study, researchers are finding it difficult to tie the die-off to any single factor, said Maryann Frazier, a senior extension associate in Penn State University’s entomology department. “Two things right now … that are really keeping us focused are the pathogen and the role of pesticides,” Frazier said.
Hackenberg, 58, trucks his bees around the country for pollination — from oranges in Florida to blueberries in Maine. He was the first beekeeper to report the disorder to Penn State researchers last fall, having lost nearly 75 percent of his 3,200 colonies. He said he is convinced pesticides, and in particular a kind of pesticide called neonicotinoids, were harming his bees.
More here.