Neonicotinoids cause honeybee infertility, finds report

Two widely used neonicotinoid pesticides have been found to significantly reduce the fertility of male honeybees - and could provide vital evidence for the species population decline.

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That’s according to a new study from the Institute of Bee Health University of Bern, Switzerland, which explored how neonicotinoids affect male honeybee (drones) reproduction.

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Researchers discovered that the globally-used neonicotinoids; thiamethoxam and clothianidin, could serve as inadvertent insect contraceptive. The study suggests that this could provide explanation for the steady decline of honeybee numbers and other wild insect pollinators throughout the northern hemisphere.

As part of the study, honeybee drones were exposed to the neonicotinoids; thiamethoxam and clothianidin, with the results showing on average 39% less living sperm in the exposed drones.

Neonicotinoid pesticides were also found to cut the lifespan of the drones by a third, with the exposed drones living for 15 days compared to 22 days for the controls. 

“Our study clearly demonstrates that neonicotinoid insecticides can have significant lethal (lifespan) and sublethal (sperm viability and living sperm quantity) effects on honeybee drones”, say researchers.

The report also suggests that although drones do not directly contribute to colony survival their role via mating is vital for the colony.

It states: “Queen survival and productivity are intimately connected to proper mating as the depletion of sperm results in costly replacement of the queen by the colony, which can only successfully occur during specific periods of the year.”

Separate search carried out last year also found that pesticides were harmful to butterfly species. 

The UK temporarily lifted an EU ban on two neonicotinoid pesticides in 2015. 

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Image: Getty