We have carried out a functional analysis of the Ors (Odorant receptors) of the mosquito Anopheles gambiae, which transmits malaria. Female Anopheles detects and locates humans largely through olfactory cues. We have systematically expressed Anopheles odorant receptors in our in vivo expression system, the empty neuron system, and defined their functional response properties. Expression of the first Anopheles odorant receptor, AgOR1, which is expressed in females, conferred response to the odorant 4-methyl phenol, a component of human sweat. We have now identified many compounds that excite or inhibit Anopheles odor receptors. Some of these compounds may be useful in manipulating the mosquito olfactory system. Since there are 500 million clinical cases of malaria each year, even a modest improvement in mosquito control could have a significant impact on an enormous global health problem.
The range of the mosquito Aedes albopictus has expanded dramatically over the past few decades. We have been exploring the mechanisms by which its taste system contributes to feeding, egg laying, and biting decisions.
Tsetse flies, which transmit trypanosomiasis, also detect their hosts in large part through chemosensory cues. We have identified a volatile sex attractant of the tsetse fly. Methyl palmitoleate (MPO) acts as an aphrodisiac, elicits sex-specific behavioral effects, and evokes sexually dimorphic physiological responses. It also elicits species-specific behavioral and physiological effects. Our work invites exploration of whether MPO may be useful in tsetse control. We also found that infection with trypanosomes affects both the chemical profile and sexual behavior of tsetse.
A fruit fly and a tsetse fly. Courtesy of G. Attardo.
References
Baik, LS and Carlson J.R., (2020) The mosquito taste system and disease control, PNAS 117(52):32848-32856.
Soni, N., Chahda, J.S., Carlson, J.R., (2019) Odor coding in the antenna of the tsetse fly Glossina morsitans, PNAS 116(28):14300-14308 (cover article).
Chahda, J.S., Soni, N., Sun, J. Ebrahim, S., Weiss, B., and Carlson, J.R. (2019) The molecular and cellular basis of olfactory response to tsetse fly attractants, PLoS Genetics, 15(3):e1008005.
Carey, A., Wang, G., Su, C.-Y., Zwiebel, L., and J. Carlson (2010). Odor reception in the malaria mosquito Anopheles gambiae Nature 464, 66-71.
Wang, G. Carey, A., Carlson, J. and Zwiebel, L. (2010). The molecular basis of odor coding in the malaria vector mosquito Anopheles gambiae. PNAS 107, 4418-4423.
Hallem, E., Fox, N., Zwiebel, L., and Carlson, J. (2004) Olfaction: Mosquito Receptor for Human-Sweat Odorant, Nature 427, 212-213.