Animal behaviour: Diesel exhaust pollution can throw bees off the scent

Exposure to common air pollutants found in diesel exhaust pollution can affect the ability of honeybees to recognize learnt floral odours, research in Scientific Reports this week suggests. Honeybees use floral odours to help locate, identify and recognize the flowers from which they forage. The authors speculate that these changes may potentially affect honeybees’ foraging efficiency and, ultimately, could affect the pollination services that these insects supply.

The honeybee (Apis mellifera) has a sensitive sense of smell and an exceptional ability to learn and memorize new odours. NOx gases (nitric oxide and nitrogen dioxide) represent some of the most reactive gases produced as a result of the combustion of diesel and other fossil fuels, but the emissions limits for nitrogen dioxide are regularly exceeded, especially in urban areas.

Tracey Newman and colleagues studied whether diesel exhaust pollution alters the components of a synthetic floral odour blend. They examined the potential role of highly reactive gases at environmentally relevant concentrations in such changes, and the potential effects the changes elicited could have on honeybee recognition of floral blends.

The results indicate that NOx gases - particularly nitrogen dioxide - may be capable of disrupting the odour recognition process that honeybees rely on for locating floral food resources. 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.