Current Projects

Role of olfactory cues and modulation of olfactory-driven behavior in triatomine insects

I continue working on research projects of sensory physiology in one the main vector of Chagas disease (the nocturnal blood-sucking bug Rhodnius prolixus) started at the University of Arizona. While insects rely on a variety of sensory cues to obtain information about food, mates, predators, and oviposition sites, it is known that both internal and external factors modulate sensory responses. In particular, I am studying the modulatory effects of the hunger status and time of the day on olfactory function in triatomines using behavioral and electrophysiological recording techniques.

In another project, in collaboration with John Hildebrand and Teresa Gregory (University of Arizona), we are seeking to parse-out odorant and odorant mixtures that could ultimately be used in traps to monitor the presence of triatomines in human houses. We developed a new “pit” trap design that successfully recruits insects when baited with an attractive odor lure. Using chemical ecology techniques, we are trying to find out which odorants within the yeast fermentation products are crucial to lure insects into these traps. Because sensory cues that guide host-seeking behavior in blood-sucking insects are highly parsimonious, these studies can contribute to find solutions for controlling insect vectors of other human diseases such as malaria, yellow fever and dengue.

 

Evolution and function of taste in the Drosophila genus

The genus Drosophila has over 2,000 species inhabiting a wide range of ecological habitats, from tropical rainforests to deserts. As for most insects, the chemical senses -olfaction and taste- mediate a variety of behavioral decisions such food, host, and mate-finding. While some species use a wide range of substrates for feeding and oviposition, other species use a single or closely related number of hosts. In particular, studies in several Drosophila species have shown that chemosensory genes involved in host specialization are under non-neutral selection. For instance, in specialist species such as D. sechellia and D. erecta, which respectively feed almost exclusively on the Morinda citrifolia (Noni) fruit and screw pine fruits (Pandanus candelabrum), host specialization is associated with an accelerated loss of chemosensory receptor proteins, particularly of bitter gustatory receptors. A possible explanation for this is that specialists, by virtue of using just one or few related hosts, need fewer chemosensory receptors because they are exposed to fewer harmful compounds. Alternatively, the lost bitter gustatory receptors maybe those involved in the detection of specific compounds that deterred a generalist ancestor (McBride and Arguello 2007, Genetics 177: 1395-1416). Furthermore, in these two species, corresponding olfactory specializations that mediate host finding have been described at the behavioral level and at the peripheral and central nervous system level (Dekker et al. 2006, Current Biol. 16: 101-109; Linz et al. 2013, Proc. Royal Soc. London B 280: 20130626). Other interesting chemosensory specializations related to lifestyle have also been described in other Drosophilidae species (Goldman-Huertas et al. 2015, Proc. Natl. Acad. Sci USA 112: 3026-3031; Revadi et al. 2015, Physiol. Entomol. 40: 54–64).

In Dr. Scott lab, I am investigating the behavioral and neural mechanisms underlying taste specializations (including the functional consequences of the loss of bitter gustatory receptors) in specialist species (such as D. sechellia) and the related sibling species. From a comparative standpoint, I am interesting in testing whether there is a common neural organization and pattern mediating taste function across species.