Olfaction is an essential primary sensory modality for insects that effects a wide range of inter- and intraspecific interactions such as food location, predation, oviposition, finding mates, and learning. In particular, Anopheles gambiae, the principal African malaria vector mosquito relies heavily on olfactory information in order to locate a human host. This strong preference for human blood meals is a characteristic olfactory-based behavioral feature of An. gambiae known as anthropophily. In this regard, disturbing the interaction between human odorants and olfactory system of this mosquito represents a possible approach to control olfactory driven behaviors such as blood feeding by female mosquitoes. Recent studies have identified a large family of putative odorant receptors in An. gambiae (AgORs) and may provide a better understanding of molecular and neural mechanisms underlying olfactory processing in the periphery as well as central nervous system, thus providing rational strategies to olfactory-based malaria control programs. The objectives of the research proposed here is to broadly characterize olfactory responses in the proboscis type 2 (T2) sensilla where AgOR7, a highly conserved non-conventional odorant receptor, is widely expressed. In the course of these studies, I propose to establish the complete olfactory repertoire of the proboscis of An. gambiae using single sensillum recording techniques, molecularly define the AgORs underlying these responses using single sensillum RT-PCR. Previous studies on central projection patterns of identified proboscis neurons to the antennal lobes demonstrated that olfactory processing in the proboscis could be discrete from other olfactory organs, providing new insight into neural mechanisms underlying olfactory signal integration. Taken together, I also propose to characterize expression patterns of AgORs in the proboscis as well as more specifically in an individual T2 sensilla by using in situ hybridization techniques. Characterization of olfactory spectra as well as an increased understanding of olfactory processing mechanisms in this accessory olfactory organ of the malaria vector mosquito will likely provide critical information as to how mosquitoes utilize the proboscis for detecting salient odorant information from a human host. As such, the studies proposed here provide new insight into basic knowledge of insect chemosensory processes as the specifics of mosquito olfactory processes. Ultimately, these may result in new ideas for future mosquito control strategies that target these novel olfactory responses.
