From: Lisa Marie Potter, MONGABAY.COM, More from this Affiliate
Published December 11, 2014 10:57 AM

Pollution May Cause Problems for Pollinators

While unpleasant car exhaust makes us wrinkle our noses, such human-made fumes may pose serious problems to insects searching for nectar. Researchers recently revealed that background odors make finding flowers difficult for pollinators.

The study, published in Science, measured how hawk moths (Manduca sexta) pick out the sacred datura flower scent (Datura wrightii) amidst all the other smells that waft through the environment. Datura’s brilliant 15-centimeter trumpets leap from dark, heart-shaped leaves, sending smelly signals into the arid sky of the southwestern deserts where they grow.

“When you look at these flowers, they’re wonderful—almost like sensory billboards or advertisements,” said neurobiologist and lead author Jeffrey Riffell from the University of Washington in an interview with

The moths navigate over a sea of brush, following the datura aromas among flower patches separated by kilometers. The task is difficult. The blossoming bugles grow in dense stands of creosote (Larrea tridentata), flowers with the Mexican nickname hediondilla, or “the little stinker.” The stinker’s smell can overwhelm the moth, masking the datura scent.

The researchers spent the sweltering summer in Arizona’s desert in a mobile laboratory within a shipping container, sampling the environment’s volatile recipe. The team is the first to use a mass spectrometer to measure plant aromatics; the instrument usually measures atmospheric chemistry.

“These chemicals are messages. They are signals moving back and forth,” environmental chemist and co-author Leif Abrell from the University of Arizona told “We took the portable mass spectrometer out into the natural environment in the desert, where the moth would normally experience its life—finding flowers, finding mates, looking for food, looking for places to lay its eggs.”

Once the scientists decoded the smells, they recreated the complex wafting of datura’s scent in a wind tunnel in the lab, where artificial “breezes” made the pungent plumes curl and diffuse as they do in the desert. The moths flew freely amidst the flower scent for three minutes while the scientists noted each flutter, hover, and final sip of nectar. Then they recorded how increasing the datura scent’s frequency and adding background scents affected the moths’ ability to find the flower. Scientists used creosote, the background odor present in the desert environment, and exhaust fumes—similar in chemical composition to the natural odors from creosote and datura. 

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Hawk moth image via Shutterstock.

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