Bees develop nicotine-like addiction to pesticides, says study

Research suggests the more neonicotinoids bumlebees ingest, the more they want Picture: Philip Jone

Research suggests the more neonicotinoids bumlebees ingest, the more they want Picture: Philip Jones - Credit:

Bumblebees acquire a taste for food laced with neonicotinoid pesticides that can be compared to nicotine addiction in smokers, say scientists.

The more of the nicotine-like chemicals they consume, the more they appear to want, a study has shown.

The findings suggest that the risk of potentially harmful pesticide-contaminated nectar entering bee colonies is higher than was previously thought.

In a series of studies, a team of British researchers offered bumblebees a choice of two sugar solutions, one of which was laced with neonicotinoid pesticides.

They found that over time the bees increasingly preferred feeders containing the pesticide-flavoured sugar.

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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.”

Controversial neonicotinoid pesticides are chemically similar to nicotine, the addictive compound in tobacco.

In 2013 the European Union imposed a partial ban on three widely used neonicotinoids because of evidence that they may be harmful to bees.

The ban has now been extended to cover all crops not grown in greenhouses, despite strong opposition from some groups including the UK’s National Farmers’ Union.

Scientists carrying out the new research tracked 10 bumblebee colonies over 10 days. Each colony had access to its own foraging area in which the researchers had set up sugar-dispensing feeders.

Lead scientist Dr Andres Arce, also from Imperial’s Department of Life Sciences, said: “Many studies on neonicotinoids feed bees exclusively with pesticide-laden food, but in reality, wild bees have a choice of where to feed. We wanted to know if the bees could detect the pesticides and eventually learn to avoid them by feeding on the uncontaminated food we were offering.

“Whilst at first it appeared that the bees did avoid the food containing the pesticide, we found that over time the bumblebees increased their visits to pesticide-laden food.

“We now need to conduct further studies to try and understand the mechanism behind why they acquire this preference.”

The findings are reported in the journal Proceedings of the Royal Society B.

Dr Gill added: “Whilst neonicotinoids are controversial, if the effects of replacements on non-target insects are not understood, then I believe it is sensible that we take advantage of current knowledge and further studies to provide guidance for using neonicotinoids more responsibly, rather than necessarily an outright ban.”

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