EAGER: Do Air Pollutants Modify the Strength and Quality of Floral Scents?

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Chemical signals consisting of volatile organic compounds emitted by plants play important roles in ecological interactions and atmospheric chemistry. Recently, it was hypothesized that such interactions may be perturbed by air pollution: In polluted air masses, floral scents are destroyed by chemical reactions and therefore travel less far than in clean air, which may alter the pollination patterns of flowering plants. This project involves laboratory and field experiments to explore which scent-mediated interactions are likely to be affected by pollutants. Floral scents and products arising from their reactions with ozone, hydroxyl radical, and nitrate radical are being investigated in the laboratory to learn their chemical and scent attributes. Olfactory responses of pollinators to threshold amounts of individual compounds and mixtures are also being quantified through laboratory studies. In the field, spatio-temporal variations in olfactory signals within and above alfalfa plant canopies will be investigated in situ at the Penn State University Entomology Farm where alfalfa will be grown during the 2010 growing season. Alfalfa flowers will be studied for their volatile emissions. Honey bees and alfalfa leaf cutter bees will be used in the scent-insect interaction studies. The anticipated results will indicate whether the ambient "blend composition" of parent floral scents and reaction products exist in the threshold amounts necessary to stimulate a response by pollinators.This exploratory research will provide crucial information that ecologists, agronomists, and atmospheric scientists can utilize to develop broader studies to assess the impacts of airborne pollution on pollination of flowering plants. Data sets will be used to develop and update numerical models to estimate the effective distances traveled by floral plumes away from sources. With the view to enhance diversity in ecology and atmospheric sciences, at least one minority student will be recruited to participate in all facets of the research.