A concerning new study has found that something we rely on for our crops may be responsible for helping decimate bee populations worldwide. The study found that a commonly used insecticide is killing much of hte sperm that male drone honey bees create, resulting in dwindling bee numbers.

Neonicotinoids, the insecticide, doesn’t kill the drones but rather reduces their sperm count by 39 percent based on experiment by Swiss scienitsts, according to the paper, which was published in the Proceedings of the Royal Society B.

Basically, the insecticide is acting as a contraceptive for drones, who need to mate with the queen in order for the hive to produce offspring. Drones have no other purpose other than to mate, and they die after mating. The insecticide doesn’t appear to prevent them from mating and impregnating the queen, it just makes it more difficult for them to do so.

The study found that bees that ate pollen without pesticides produced an average of 1.98 million living sperm versus 1.2 million for one that ate pollen with neonicotinoids.

“Our results demonstrate for the first time that neonicotinoid insecticides can negatively affect male insect reproductive capacity, and provide a possible mechanistic explanation for managed honeybee queen failure and wild insect pollinator decline,” the paper’s abstract states. “The widespread prophylactic use of neonicotinoids may have previously overlooked inadvertent contraceptive effects on non-target insects, thereby limiting conservation efforts.”