Diesel and gas exhaust prevents bees from smelling flowers

Bees face many threats, and now scientists have found that both diesel and gas exhaust from our cars is disrupting the insects' ability to smell flowers.

The researchers, led by Tracey Newman and Guy Poppy, note that this study does not link such odor alterations to the colony collapse phenomenon or other mass bee deaths. But they do say that preventing plants from communicating with their best pollinators is an added problem the bees don't need.

The scientists taught laboratory honey bees to recognize a blend of eight floral chemicals synthesized from rapeseed. They added diesel exhaust to that aroma in various concentrations, including levels consistent with environmental health standards in Europe and the U.S.

“Within one minute of exposure the abundances of four of the chemicals were significantly lowered, with two components rendered undetectable,” wrote the researchers.

“Honeybees were trained to recognize the full synthetic odor mix; altering the blend, by removing the two chemicals rendered undetectable, significantly reduced the ability of the trained honeybees to recognize the altered odor.”

But it's not just diesel. Researchers also tested the effect of nitrogen dioxide, a component in the exhaust from gasoline vehicles. When the scientists exposed the bees to nitrogen dioxide emissions permitted by European and US regulators for humans, their ability to detect four of the eight odor components.

Bees are the primary pollinators of global crops worth an estimated $248 billion, and researchers warn that further research is needed on the mechanisms involved in honeybee declines.