The Effects of Diesel Exhaust Pollution on Floral Volatiles and the Consequences for Honey Bee Olfaction
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There is growing evidence of a substantial decline in pollinators within Europe and North America, most likely caused by multiple factors such as diseases, poor nutrition, habitat loss, insecticides, and environmental pollution. Diesel exhaust could be a contributing factor to this decline, since we found that diesel exhaust rapidly degrades floral volatiles, which honey bees require for flower recognition. In this study, we exposed eight of the most common floral volatiles to diesel exhaust in order to investigate whether it can affect volatile mediated plant-pollinator interaction. Exposure to diesel exhaust altered the blend of common flower volatiles significantly: myrcene was considerably reduced, β-ocimene became undetectable, and β-caryophyllene was transformed into its cis-isomer isocaryophyllene. Proboscis extension response (PER) assays showed that the alterations of the blend reduced the ability of honey bees to recognize it. The chemically reactive nitrogen oxides fraction of diesel exhaust gas was identified as capable of causing degradation of floral volatiles.
KeywordsFloral scent compounds Diesel exhaust Nitrogen oxides Scent degradation Scent recognition Proboscis extension response
We acknowledge Wittko Francke for valuable comments on the manuscript, Christine M. Reitmayer for help with beekeeping. We also thank the Erbilgin lab at the University of Alberta for providing us with a trans-verbenol mass spectrum. Funding for this research has been provided through the Leverhulme Trust Research Project Grant RPG-089.
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