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 didnt kill the drones. But bees that ate treated pollen produced 39 percent less live sperm than those that didnt, according to a controlled experiment by Swiss researchers published Wednesday in the journal Proceedings of the Royal Society B.