"WASHINGTON -- A new study finds that a commonly used insecticide kills much of the sperm created by male drone honey bees, one reason why the bees are dwindling.

The class of insecticide called neonicotinoids didn't kill the drones. But bees that ate treated pollen produced 39 percent less live sperm than those that didn't, according to a controlled experiment by Swiss researchers published Wednesday in the journal Proceedings of the Royal Society B.

It essentially acted as an accidental contraceptive on the drones, whose main job is to mate with the queen — but not one that prevented complete reproduction, just making it tougher, said Lars Straub, lead author of the study and a doctoral student and researcher at the University of Bern. Drones, which are the product of unfertilized eggs, don't gather nectar or pollen and don't sting; they die after mating."

Seth Borenstein reports for the Associated Press July 26, 2016. [2]