In spite of denials that claim neonicatinoid pesticides are not lethal to bees, a new Harvard study fingers neonics as the key driver of colony collapse disorder. The experiment couldn't have been simpler. Working with nearby beekeepers, Harvard researcher Chensheng Lu and his team treated 12 colonies with tiny levels of neonics and kept six control hives free of the popular chemicals. All 18 hives made it through summer without any apparent trouble. Come winter, though, the bees in six of the treated hives vanished, leaving behind empty colonies—the classic behavior of colony collapse disorder. None of the six control hives experienced a CCD-style disappearing act, although one did succumb to a common-to-bees gut pathogen called nosema.
This year, beekeepers in Ohio, for example, reported winter losses of 50 percent to 80 percent.Last year, Europe placed a two-year moratorium on most neonic uses, pending more research on their effect on honeybees. The US Environmental Protection Agency, for its part, is reviewing its registration of the chemicals, and won't be done until 2016 at the earliest.