The bee population has been mysteriously declining and diesel fumes may be part of the problem.

A new study found that air pollutants from diesel exhaust could be inhibiting bees' ability to sniff out flowers, which are essential for their survival, a University of Southampton press release reported.

Honeybees use floral odors to find where the pollen is. The diesel fumes change the flowers' scent profile. The changes could affect the bees' "foraging efficiency" and could also make an impact on "pollination and thus global food security."

"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," Tracy Newman, a neuroscientist at the University, said.

The research team took eight chemicals that are present in rapeseed flower oil and mixed them with both clean air and diesel- polluted air. Six of the chemicals reduced in concentration when mixed with the polluted air and two of them disappeared completely after only one minute.

This finding means the chemical composition of the floral scent completely changed once it was introduced to air containing diesel fumes.  When the chemicals were mixed with clean air they were completely unaffected.

 "Honeybee pollination can significantly increase the yield of crops and they are vital to the world's economy - £430 million a year to the UK alone. 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. 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," Guy Poppy, an ecologist at the University, said.