Since 2006, a phenomenon known as Colony Collapse Disorder (CCD) has affected managed honey bee hives by decreasing populations. Researchers studying the causes of CCD have found many possibilities, including invasive mites, pathogens, pesticide residues, poor nutrition, habitat loss, and stress.

Now scientists in the UK are suggesting another possible cause: diesel fumes.

According to an article published in Scientific Reports called “Diesel exhaust rapidly degrades floral odours used by honeybees,” exhaust fumes may hinder the bees’ ability to find flowering food sources by decreasing their sense of “smell.”

“Flowers have evolved to produce chemical mixtures that attract pollinators,” said lead researcher Dr. Guy Poppy. However, the airborne pollution is interfering with relationship between plants and pollinators.

“Such changes in recognition may impact upon a honeybee’s foraging efficiency and therefore the pollination services that they provide,” the authors wrote.

Click here for a BBC video showing how the researchers tested the bees’ sense of smell.

The study mixed eight chemicals found in the odor of oil rapeseed flowers with clean air and with air containing diesel exhaust. 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 odor that was mixed with the clean air was unaffected.

Furthermore, when the researchers used the same process with NOx gases (nitric oxide and nitrogen dioxide), which is found in diesel exhaust, they saw the same outcome, suggesting that NOx was a key facilitator in how and why the odor’s profile was altered.

Dr Tracey Newman, a neuroscientist at the University of Southampton, said, “Honeybees have a sensitive sense of smell and an exceptional ability to learn and memorize new odors. 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 odor blend, which affects the honeybee’s recognition of the odor. This could have serious detrimental effects on the number of honeybee colonies and pollination activity.”

Read more at:

– Diesel exhaust rapidly degrades floral odours used by honeybees

– Diesel exhaust stops honeybees from finding the flowers they want to forage

– Revealed: traffic fumes are confusing bees in their hunt for food

– Bees’ foraging for flowers ‘hampered by diesel exhaust’

– Are Diesel Exhaust Fumes to Blame for Honeybee Colony Collapse?