Bumblebees become addicted to pesticides in the same way smokers crave nicotine, a new study has found.
Neonicotinoid pesticides are chemically similar to nicotine and research by scientists at Imperial College, London found the more bees consumed, the more they seemed to want.
Bumblebees were offered a choice of two sugar solutions, one of which was laced with neonicotinoid pesticides.
Ten bumblebee colonies were monitored over 10 days, each with its own foraging area in which the researchers had set up sugar-dispensing feeders.
The aim was to find out if the bees could detect the pesticides and eventually learn to steer clear of them by feeding on the uncontaminated food being offered.
While the pesticide-laden food was avoided initially, over time the insects began to prefer it.
Dr Richard Gill, from the Department of Life Sciences at Imperial College London, said: "Given a choice, naive bees appear to avoid neonicotinoid-treated food.
"However, as individual bees increasingly experience the treated food they develop a preference for it.
"Interestingly, neonicotinoids target nerve receptors in insects that are similar to receptors targeted by nicotine in mammals.
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"Our findings that bumblebees acquire a taste for neonicotinoids ticks certain symptoms of addictive behaviour, which is intriguing given the addictive properties of nicotine on humans, although more research is needed to determine this in bees."
In April this year the EU banned the three main neonicotinoids, clothianidin, imidacloprid and thiamethoxam, for all outdoor uses, because of concerns over their effects on pollinators.