Bees really can't catch a break at the moment. New research, published in Scientific Reports, from the University of Southampton, England, shows that diesel exhaust significantly affects the scent of flowers in the air, which could hinder honeybees from recognizing those floral odors. As important pollinators, ultimately this could spell bad news for food production and security.
The team, led by Dr Tracey Newman and Professor Guy Poppy, created a synthetic blend of the eight chemical scents found in oil rapeseed flowers and then they mixed it with clean air and air containing diesel exhaust. The chemicals in the blend were combined in the same proportion that they are naturally emitted by the flowers.
When the scents were mixed with the diesel fumes, within one minute of exposure, two out of the eight chemicals could no longer be picked up by detectors, and the abundance of two others was significantly reduced. But when the scents were mixed with clean air, such changes were not observed.
The experiment was then repeated by using only NOx, an extremely toxic mixture of nitric acid and nitrogen oxide emitted by diesel cars. The team found a reduction in the abundance of the same four chemicals, suggesting that exposure to NOx is the main cause of the changes in the chemical composition of the scent blend.
To find out whether this could potentially affect foraging ability, the team started off by training honeybees to recognize the full blend of scent. Afterward, the honeybees were presented with different blends of scent prepared to mimic the effects of diesel fumes. The ability of insects to recognize the modified scents was significantly impaired: less than 30% of bees could still identify the blends as a flower scent.
“Honeybee pollination can significantly increase the yield of crops and they are vital to the world’s economy – £430 million [$660 million] a year to the UK alone,” Professor Poppy, one of the lead authors, said in a statement. “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.”
Top Image Credit: Honey Bee on Indian Blanket, by TexasEagle, via Flickr. CC BY-NC 2.0