What’s tipping honeybee populations into huge annual die-offs? For years, a growing body of evidence has pointed to a group of insecticides called neonicotinoids, widely used on corn, soy, and other US crops, as a possible cause of what has become known as colony collapse disorder (CCD).
Rather than kill bees directly like, say, Raid kills cockroaches, these pesticides are suspected of having what scientists call “sub-lethal effects”—that is, they make bees more vulnerable to other stressors, like poor nutrition and pathogens. In response to these concerns, the European Union recently suspended most use for two years; the US Environmental Protection Agency, by contrast, still allows them pending more study.
But according to a new peer-reviewed paper, neonicotinoids aren’t the only pesticides that might be undermining bee health. The study, published in PLOS One and co-authored by a team including US Department of Agriculture bee scientist Jeff Pettis and University of Maryland entomologist Dennis vanEngelsdorp, found that a pair of widely used fungicides are showing up prominently in bee pollen—and appear to be making bees significantly more likely to succumb to a fungal pathogen, called Nosema ceranae, that has been closely linked to CCD. The finding is notable, the authors state, because fungicides have so far been “typically seen as fairly safe for honey bees.”