Diesel fumes hamper honeybees’ flower scent, study finds

University of Southampton research finds diesel fumes can affect honeybees ability to locate flowers to pollinate

Exposure to common air pollutants found in diesel exhaust pollution can affect the ability of honeybees to recognise floral odours, research by the University of Southampton has found.

According to the university’s Dr Tracey Newman and Professor Guy Poppy — who both led the research team — honeybees use floral odours to help locate, identify and recognise the flowers from which they forage.

Honeybees’ ability to recognise floral odour may be hampered by diesel exhaust fumes

However, they found that diesel exhaust fumes can change the profile of flora odour, which may affect honeybees’ foraging efficiency and could ultimately affect pollination and global food security.

Published yesterday (October 3)in the research journal Scientific Reports, the study involved mixing eight chemicals found in the odour of oil rapeseed flowers with clean air and with air containing diesel exhaust.

The results showed six of the eight chemicals reduced (in volume) when mixed with the diesel exhaust air and two of them disappeared completely within a minute, meaning the profile of the chemical mix had completely changed. The odour that was mixed with the clean air was unaffected.

Furthermore, when the researchers used the same process with nitric oxide and nitrogen dioxide gases — also found in diesel exhaust — they saw the same outcome, suggesting that nitrogen oxides (NOx) were a key facilitator in how and why the odour’s profile was altered. The changed chemical mix was then shown to honeybees, which could not recognise it, the scientists said.

‘detrimental effects’

Commenting on the findings, neuroscientist Dr Newman said: “Honeybees have a sensitive sense of smell and an exceptional ability to learn and memorise new odours. NOx gases represent some of the most reactive gases produced from diesel combustion and other fossil fuels, but the emissions limits for nitrogen dioxide are regularly exceeded, especially in urban areas.

“Our results suggest that that diesel exhaust pollution alters the components of a synthetic floral odour blend, which affects the honeybee’s recognition of the odour.”

Dr Newman added that this could have “serious detrimental effects” on honeybee colonies and pollination activity.

Ecologist Professor Poppy said that honeybee pollination could significantly increase the yield of crops, which was worth £430 million a year to the UK economy alone.

He added: “Honeybees use the whole range of chemicals found in a floral blend to discriminate between different blends, and the results suggest that some chemicals in a blend may be more important than others.”

The University of Southampton-led research was funded by the Leverhulme Trust.