Professor and Department Chair
W355 Seeley G. Mudd Hall
Phone: (607) 254-4353
Web Page: Raguso Lab
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.
Recent Experimental Studies:
Arguello, J.R., C. Sellanes, Y-R. Lou, R.A. Raguso. 2013. Can yeast (S. cerevisiae) metabolic volatiles provide polymorphic signaling? PLoS ONE 8(8): e70219.
Friberg, M., C. Schwind, R.A. Raguso, J.N. Thompson. 2013. Extreme divergence in floral scent among woodland star species (Lithophragma spp.) pollinated by floral parasites. Annals of Botany 111: 539-550.
Parachnowitsch, A.L., R.A. Raguso, A. Kessler. 2012. Phenotypic selection to increase floral scent emission, but not flower size or colour in bee-pollinated Penstemon digitalis. New Phytologist 195: 667-675.
von Arx, M., J. Goyret, G. Davidowitz, R.A. Raguso. 2012. Floral humidity as a reliable sensory cue for profitability assessment by nectar-foraging hawkmoths. Proceedings of the National Academy of Sciences, USA 109: 9471-9476.
Galen, C., R. Kaczorowski, S.L. Todd, J. Geib, R.A. Raguso. 2011. Dosage-dependent impacts of a floral volatile on pollinators, larcenists and the potential for floral evolution in the alpine skypilot, Polemonium viscosum. The American Naturalist 177: 258-272.
Recent Perspectives and Reviews:
Raguso, R.A. 2013. Commentary: small molecules mediate bacterial farming by social amoebae. Proceedings of the National Academy of Sciences, USA 110: 14512-14513.
Raguso, R.A. 2012. New Synthesis: Exploring the chemical links in ecological food webs. Journal of Chemical Ecology 38: 441.
Raguso, R.A. 2011. For love of Eisner. Journal of Chemical Ecology 37: 546-547.
Introduction to Behavior (BioNB 2210), Chemical Ecology (BioNB 3690), Plant Behavior (BioNB 4460) and Animal Communication (BioNB 4260)