No one likes to breathe in exhaust fumes from a diesel engine, and come to find out neither do bees. A recent study published in Scientific Reports has revealed that honeybees’ ability to find flowers diminishes when the bees are exposed to the chemicals that diesel fuel puts into the air, namely NOx. The scientists of the study recognize this as a sign for people to step up the air quality control.

“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,” said University of Southampton neuroscientist Dr. Tracey Newman, who was involved in the work.

The research team wanted to determine the chemical effects of pollution on pollinators, and to do that they designed a research project that had two facets. First they created their own floral aroma using oilseed rape. The team used a diesel-powered generator to create a mixture of air and exhaust that closely mimicked the air on a busy road. They mixed this recreation air with the floral scent mix.

“We saw that there was loss of two of the components [of the floral odor mixture],” Newman said. The two “lost” compounds had reacted chemically with the mono-nitrogen oxide, commonly known as NOx or diesel exhaust.

Now that the team had determined the chemical pollution affected the chemistry of floral scents, they started the second step to the research, which was determining how bees reacted to this change. To do that, they created a little bit of a Pavlov’s test with the bees, teaching them to associate the chemical floral aroma mix they created with sugary liquid. Bees stick their tongues out when drinking the liquid—just like when drinking nectar. So after a few trials, the bees would stick their tongue out once they first smelled the floral mix.

“Having trained a bunch of bees, we then tested to see if they would respond in the same way to the mixture that was depleted by exposure to NOx,” said Newman. When the NOx degraded the chemicals of the floral mixture, the bees did not respond to the smell and would not stick out their tongues.

This study was one of the first to look at the effects of pollution on bees beyond pesticides.  “Bees are subject to a much wider variety of pollutants and contaminants,” said Prof James Nieh, who studies honeybee health and behaviour at the University of California San Diego, “The influence and potential synergy of these pollutants with pesticides should be studied.”