The world’s most common insecticide stops bees from buzzing, preventing them from shaking out flowers’ pollen, a study has found.
Neonicotinoids hinder bumblebees’ efforts to learn to buzz, which is crucial for collecting pollen from some flowers.
While the pesticide is the most widely used globally, it is currently banned on flower crops in Europe, following a moratorium imposed in 2013.
However, the temporary ban is set to be reviewed next year.
Previous research also shows that neonicotinoid pesticides reduce learning and memory in bees.
“Bees produce a vibration – or buzz – to shake pollen out of these anthers like a pepper pot,” Penelope Whitehorn of the University of Stirling in Scotland, who led the study, told the Guardian.
“The bee lands on a flower, curls her body around the anther and grips the base with her mandibles. She then rapidly contracts the flight muscles to produce the vibration, without beating her wings.”
In the experiments, the colony of bumblebees not exposed to the pesticide got consistently better at buzzing pollen from flowers.
But those fed 10 parts per billion (ppb) solutions of thiamethoxam did not improve at all, despite repeated attempts.
The results are set to be presented at the British Ecological Society’s annual meeting today (Tuesday).
Whitehorn said: “The implication is the bees take less pollen back to the colonies and the colonies will be less successful, meaning there may be fewer pollinators overall.”
A study earlier this year found that neonicotinoids cut live sperm in male bees by 39%.
A spokesman for Syngenta, which manufactures thiamethoxam, said: “Crop-measured pollen and nectar residues from thiamethoxam seed-treated oilseed rape is typically less than 3ppb. In all our thiamethoxam seed-treated oilseed rape field studies we have never recorded a pollen or nectar residue as high as 10ppb.”
Bees fertilise more than three quarters of the world’s food crops.