Messinger, Olivia J , Sipes, S.D. .
For just a few scents more. The characterization of floral scent in plants visited by the specialist bee, Diadasia.
Specialization in bees is the condition in which a species collects pollen from only a subset of available floral hosts; it is estimated that over half of the world’s 30,000 bees specialize. The means by which bees recognize their host plants are not fully understood, nor are the mechanisms governing their fidelity. This becomes especially intriguing when considering specialist bee clades whose species have radiated onto multiple, distantly related host plant families. How do these evolutionary switches to new host plant families take place? We have been investigating the hypothesis that specialization is a physiological constraint; specialists are unable to recognize scent compounds and/or visual displays presented by plants that are otherwise perfectly suitable floral hosts. Diadasia is a clade of specialists in which different species specialize on distantly related plant families (Asteraceae, Onagraceae, Cactaceae, Malvaceae, and Convolvulaceae). Through our investigations with this genus, we are establishing the relative importance of visual and chemical cues in their host relationships. Our approach is three-pronged, involving 1) identification of scent compounds and uv-vis reflectance patterns of Diadasia host plants, 2) behavioral experiments with manipulated floral displays and scents, and 3) electroantennographic work comparing scent compound presence to antennal excitement for Diadasia. Here, we present a summary of our ongoing work characterizing the floral scent of these plants. Using GC/MS, we analyzed 145 samples in 16 taxa representing pollen hosts of all North American Diadasia species and abundant co-blooming non-host plants. Based on similarity of peak retention time and of mass spectra, we have identified a suite of compounds that are shared across sampled Diadasia-visited taxa. All compounds, however, co-occur in non-host plants. More intriguing, the scent profiles of non-host plants appear to include a large suite of compounds not found in Diadasia host plants.
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1 - Southern Illinois University Carbondale, Plant Biology, Life Science II 420, 1125 Lincoln Drive, Carbondale, IL, 62901-6509, USA
2 - Southern Illinois University Carbondale, Plant Biology and Center for Ecology, 1125 Lincoln Dr., mail code 6509, Carbondale, Il, 62901, USA
floral host choice
Presentation Type: Oral Paper:Papers for Topics
Location: 551B/Convention Center
Date: Wednesday, August 4th, 2010
Time: 8:30 AM