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Pollution may be dwindling our flowers, a new study suggests.

Scientists found that honeybees are unable to recognize floral smells when exposed to common air pollutants found in diesel exhaust fumes.

Researchers at the University of Southampton found that chemicals in diesel exhaust fumes changes the profile of flora odor, which may affect honeybees' foraging efficiency. Researchers said that this could ultimately affect pollination and thus global food security.

Researchers mixed eight chemicals found in the odor of oil rapeseed flowers with clean air and with air containing diesel exhaust.

While the odor that was mixed with clean air was unaffected, six of the eight chemicals reduced in volume when mixed with the diesel exhaust air and two of them disappeared completely within a minute. Researchers say that findings suggest that exposure to diesel exhaust may completely change the profile of the floral odor chemical mix.

Additional analysis revealed that NOx gases (nitric oxide and nitrogen dioxide), which is found in diesel exhaust produced the same outcomes. Researchers say this may mean that NOx is a key facilitator in how and why the odor's profile was altered.

Afterwards, when honeybees were exposed to the changed chemical mix, the insects were unable to recognize it.

"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," study author Dr Tracey Newman said in a news release.

"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 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," added co-researcher Professor Guy Poppy of the University of Southampton.

The findings are published in the journal Scientific Reports.