Traffic fumes found to mask flower scents and confuse bees

Traffic fumes can affect how honeybees locate and identify flowers, seriously impacting their foraging efficiency with potentially damaging effects on already troubled bee populations, according to a new study.

Researchers from the University of Southampton found that common air pollutants in diesel exhaust fumes destroy key chemicals in the odour of oilseed flowers, making them smell unrecognisable to bees.

“Honeybees have a sensitive sense of smell and an exceptional ability to learn and memorise new odours”, Tracey Newman, a lecturer in clinical neuroscience at the university explained.

“The [effect of diesel fumes on flower scent] could have serious detrimental effects on the number of honeybee colonies and pollination activity.” 

The scientists conditioned bees kept in a laboratory to associate the smell of oilseed rape with food. Once the bees learned the connection they began sticking their tongues out in anticipation of food whenever they recognised the smell.

When the scent was presented without pollutants the bees recognised it 98-99% of the time. But after the scent was mixed with diesel exhaust, the bees only recognised it 30% of the time.

The scientists found that the nitrogen oxides in diesel fumes that chemically altered the smell by removing key chemicals within a minute of exposure.

The British bee populations are already under threat, with the EU voting in July to restrict a fourth insecticide linked to bee deaths, and imported colonies thought to also endanger the natives.

Commenting on the declining bee populations, Guy Poppy, a professor of ecology at Southampton who also worked on the study, said, “Diesel exhaust is not the root of the problem, but clearly, with all the other stressors, adding another one is likely to be detrimental to bee health.”

In June Defra launched a strategy to reverse the honeybee population decrease. Campaigners have called for the plan to be put into action before next spring. Friends of the Earth have launched a petition urging prime minister David Cameron to make 2013 “the Year of the Bee.” 

Further reading:

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