It's not just honeybees that are being done in, at least in part, by exposure to pesticides. A new report in Nature shows that chronic exposure to neonicotinoid and pyrethroid pesticides at levels similar to that found in fields, "impairs natural foraging behavior and increases worker mortality" in bumblebees, "leading to significant reductions in brood development and colony success."
The report goes on to say,
We found that worker foraging performance, particularly pollen collecting efficiency, was significantly reduced with observed knock-on effects for forager recruitment, worker losses and overall worker productivity. Moreover, we provide evidence that combinatorial exposure to pesticides increases the propensity of colonies to fail.
In the study, which looked at colonies of roughly 40 bees each (bumblebee colonies are far smaller than those of honeybees), found that exposure to the combination of pesticides resulted in the deaths, either in the colony or failing to return, of about two-thirds of the bees.