Honey Bees' Ability To Locate Food Masked By Diesel Fumes
October 3, 2013

Honey Bees’ Ability To Locate Food Masked By Diesel Fumes

[ Watch the Video: Honeybees Impacted By Diesel Exhaust ]

Brett Smith for redOrbit.com - Your Universe Online

Scientists are currently in search of an explanation for the decline of honeybee populations around the world and a new study published in the journal Scientific Reports has found that diesel exhaust may be playing a role.

In the study, researchers from the University of Southampton found that diesel exhaust fumes change the chemical profile of floral aroma molecules, a change that could affect honeybees’ ability to locate, identify and recognize a potential food source.

"Bees need to decipher the chemical messages they're getting (from flowers) to be able to home in on the flowers they know will give the best yield (of nectar)," study author and Southampton neuroscientist Tracey Newman told Victoria Gill of BBC News.

For their study, scientists mixed eight chemicals associated with the scent of oil rapeseed flowers with fresh air and with diesel exhaust-filled air. Volumes of six of the eight chemicals reduced when they were mixed with the exhaust-filled air and two disappeared completely within a minute, meaning their chemical profile had been completely altered. The chemicals that were mixed with the fresh air were unaffected.

To break down which component of the exhaust affected the floral molecules, researchers performed the same experiment with the ‘NOx gases’ nitric oxide and nitrogen dioxide. Both gases are found in diesel exhaust and produced the same outcome, indicating that NOx gases are the catalysts for changes to the odor molecules.

Researchers also exposed the changed chemical mix to honeybees, which could not identify it.

"Honeybees have a sensitive sense of smell and an exceptional ability to learn and memorize new odors,” Newman noted. “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,” he added. “This could have serious detrimental effects on the number of honeybee colonies and pollination activity."

Guy Poppy, an ecologist at the University, noted the impact that these chemical alterations could have on agriculture.

"Honeybee pollination can significantly increase the yield of crops and they are vital to the world's economy – ($700 million) a year to the UK alone,” Poppy said. “However to forage effectively they need to be able to learn and recognize the plants.”

“The results indicate that NOx gases -- particularly nitrogen dioxide -- may be capable of disrupting the odor recognition process that honeybees rely on for locating floral food resources,” Poppy 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."

Both researchers agreed that their findings indicate policymakers should work to improve air quality.

"We got into this, because we were aware of the impacts of airborne pollutants on human health, so it didn't seem so wild that there may be impacts that extended beyond human health," Newman said.