Faculty members from the University of Washington and University of Arizona published results from a recent study in the June 27 issue of the journal Science. The study found that air pollution can severely hinder the ability of the Tobacco Hornworm moth to locate its primary food source, the Sacred Datura flower.

The Tobacco Hornworm moth is notable for its ability to sniff out a Sacred Datura flower from hundreds of yards away. The moth will fly up to 80 miles in a single night in order to seek out food sources. However, the moth's ability to locate flowers could be in danger due to air pollution. With certain chemicals added in the background, the moth completely lost the ability to smell the Sacred Datura, to the point that it could have flown directly passed it without noticing. The researchers discovered that toluene and p-xylene, two chemicals commonly found in the air of urban environments, caused problems for the moth.

"Both volatiles influenced the AL representation of the Datura odor, and significantly decreased the moth's ability to locate the Datura flower," says [pdf] the report.

The Tobacco Hornworm was also adversely affected by some odors from other plants, but only ones that were chemically similar to that of the Sacred Datura. To discover this, the researchers put moths in a small wind tunnel and released different mixes of odors. When certain pollutants were included alongside the Sacred Datura scent, the moth could not recognize the flower. Scientists also inserted an electrode into the moth's olfactory node to directly record the activity triggered by the scents. The Datura scent alone produced an obvious and intense response, whereas when other chemicals were added in the background the neural response was only slightly above the resting state.

Although the Tobacco Hornworm moth is not a critical pollinator in urban environments, the study opens up the possibility that other pollinators could also be adversely affected by air pollution. If more important pollinators such as bees lose the ability to sense nearby flowers, the effect on the environment could be severe. The researchers intend to conduct further experiments on other insects to determine whether or not the reaction of the Tobacco Hornworm moth is unique, or whether it is merely a more sensitive indicator of a larger problem.

"These results have implications locally, where the plant community might have strong, indirect effects on the distances at which pollinators can recognize certain flowers, and potentially at larger scales due to the transport of volatiles from urban environments," says the report.