Insecticide can cut bee sperm 40%

A new study of male honeybees shows that two insecticides — banned in some European nations but still used in the United States — can significantly reduce the drones’ ability to reproduce.

The study, published in Proceedings of the Royal Society B, the leading biological research journal of the Royal Society, found thiamethoxam and clothianidin, two chemicals from the neonicotinoid family of insecticides, reduce living sperm in male honeybees, called drones, by almost 40 percent.

“We’ve been able to show for the first time that neonicotinoid pesticides are capable of having an effect on the male reproductive system,” said Lars Straub, a doctoral student at the University of Bern in Switzerland and the lead author of the study.

The effects of pesticides on honeybee populations are considered just one culprit among several factors causing periodic declines.

Neonicotinoids have been shown by other studies to harm the health of individual bees and the reproductive ability of female insects. The new study expanded on the dangers of the pesticides for males, finding bees subjected to the two chemicals had 39 percent fewer living sperm on average than bees that had not been exposed.

Dennis vanEngelsdorp, an assistant professor at the University of Maryland who focuses on honeybee health, said while the new study was “well designed,” it mostly helped to corroborate work that had already been done.

“Certainly we already know that insecticide exposure can have an effect on sperm,” he said. “What we didn’t know is that it was so immediate.”

The two neonicotinoids used in the study were banned in the European Union in 2013, but they are used on an industrial scale in the United States.