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Associate Professor W355 Seeley G. Mudd Hall Phone: (607) 254-4353 Web Page: Raguso Lab |
Research Interests
My students and I use mechanistic and comparative approaches to study chemical communication between flowering plants, their animal pollinators and natural enemies. Our experimental questions address signal production as well as signal reception, with an emphasis on the chemical dimensions of floral phenotypes (scent, nectar chemistry) and animals’ innate and learned behavioral responses to such stimuli, typically mediated by olfaction and taste. However, chemical cues rarely function alone, and a major gap to our understanding of signal evolution is how animals integrate information from multiple sensory channels. Thus, a primary focus of our research is to understand how the information content of natural odors is modified by the context in which they are produced and perceived.
Plant-pollinator relationships are famously diverse; we study the role(s) of chemical stimuli in systems ranging from highly specialized, obligate mutualisms (yuccas and yucca moths) to highly generalized plants (thistles, proteas) which anchor food webs of their own. One theme in my lab is to utilize model systems and their wild relatives (e.g. Manduca hawkmoths) to provide some of the “missing” behavioral and ecological context for otherwise well studied organisms. For example, the tobacco hornworm moth (Manduca sexta) has long been a preferred laboratory animal for neurophysiological and developmental research. Our experiments have documented scale- and context- specific use of olfactory, visual and tactile cues by these moths, at different stages of nectar foraging behavior. We have found them to be remarkably flexible in their relative dependence upon visual vs. olfactory inputs, and their ability to adjust innate preferences through operant conditioning. Our most recent work explores facultative use of floral CO2, which is perceived and utilized by these moths as a redundant floral odor. We are intrigued by what we might learn from other insects that differ in habit (diurnal vs. nocturnal) or trophic strategy (rotting fruit/sap vs. floral nectar).
Another theme of my research is to functionally dissect complex floral scent blends into “signal” and “noise” components by studying lineages of related plants in a phylogenetic context. This approach has revealed that phylogenetic constraints also shape scent composition, and that scent components frequently are correlated, either with biosynthetically related metabolites or with other floral features (pigment, trichomes) involved in plant defense. Our long-term studies of geographic variation in the floral scent chemistry of Oenothera caespitosa, a night-blooming wildflower in western North America, combine these themes with hawkmoth and bee behavior, in search of a more balanced understanding of the selective forces that shape signal evolution.
Representative Publications
Goyret, J., P.M. Markwell, R.A. Raguso. 2008. Scale- and context-dependent effects of floral CO2 on nectar foraging by Manduca sexta. PNAS: IN PRESS.
Raguso, R.A., T. Ojeda-Avila, S. Desai, M.K. Jurkiewicz, H.A. Woods. 2007. The influence of larval diet on adult feeding behaviour in the tobacco hornworm moth, Manduca sexta. Journal of Insect Physiology 53: 923-932.
Goyret, J., P.M. Markwell, R.A. Raguso. 2007. The effect of olfactory and visual stimuli decoupling on the foraging behavior of Manduca sexta. Journal of Experimental Biology 210: 1398-1405.
Goodrich, K.R., M.L. Zjhra, C.A. Ley, R.A. Raguso. 2006. When flowers smell fermented: the chemistry and ontogeny of yeasty floral scent in pawpaw (Asimina triloba: Annonaceae). International Journal of Plant Science 167: 33-46.
Svensson, G.P., M.O. Hickman, S. Bartram, W. Boland, O. Pellmyr, R.A. Raguso. 2005. Chemistry and geographic variation of floral scent in Yucca filamentosa (Agavaceae). American Journal of Botany 92: 1624-1631.
Ashman, T.L., M. Bradburn, D.H. Cole, B.H. Blaney, R.A. Raguso. 2005. The scent of a male: the role of floral volatiles in pollination of a gender dimorphic plant. Ecology 86: 2099-2105.
Raguso, R.A., M.A. Willis. 2005. Synergy between visual and olfactory cues in nectar feeding by wild hawkmoths. Animal Behaviour 65: 407-418.
Raguso, R.A. 2004. Flowers as sensory billboards: progress towards an integrated understanding of floral advertisement. Current Opinion in Plant Biology 7: 434-440.
Raguso. R.A. 2004. Why are some floral nectars scented? Ecology 85: 1486-1494.
Courses Taught
Introduction to Behavior (BioNB 221), Chemical Ecology (BioNB 369)