27/07/2016 16:07 BST | Updated 27/07/2016 16:44 BST

The World's Most Popular Insecticide Could Be Making Male Bees Infertile

It might explain an unusually high number of deaths of US honey bee colonies.

Albert Einstein famously predicted that if bees disappeared from the face of the Earth, humans would only have four years left to live.

In fact, 70 of the 100 crops that feed 90% of the world’s population are pollinated by the little striped insects.

It’s with some concern then that researchers have discovered that the world’s most widely used insecticide cuts live sperm in male bees by 39%.

The neonicotinoids didn’t kill the drones, whose primary role is to mate with the queen, but they did serve as an unintended contraceptive.

The findings could help to explain why a study earlier in the year found an unusually higher number of deaths of US honey bee colonies, which coincided with the failure of queens to reproduce in significant numbers.

The study, which was published in PLOS One, linked the queen failure to drones’ dead sperm, the Associated Press (AP) reported.

James Ross via Getty Images

Jeff Pettis, the lead author of the PLOS study, said: “Queen failure is a big problem and this helps explain it.

“It’s not the queens themselves, it’s the drones. It’s significant.”

Scientists told AP that mites, parasites, disease, pesticides and poor nutrition appear to have caused the number of bees and other pollinators to dwindle.

Pettis said he believed that poor sperm could account for as much as a third of the problem.

A representative for Bayer Crop Science, the manufacturer of neonictinoid said its scientists will look at the study, but that generally “artificial exposure to pesticides under lab conditions is not reflective of real-world experience”.

Neonicotinoids were banned by the EU from use on flowering crops in 2013.