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Multiple activities of insect repellents on odorant receptors in mosquitoes

Bohbot, J. D., Fu, L., Le, T. C., Chauhan, K. R., Cantrell, C. L., Dickens, J. C.
Medical and veterinary entomology 2011 v.25 pp. 436-0
Aedes aegypti, Xenopus, chemical inhibitors, insect attractants, insect repellents, odor compounds, oocytes, pyrethroid insecticides, receptors
Several lines of evidence suggest that insect repellent molecules reduce mosquito–host contacts by interacting with odorants and odorant receptors (ORs), thereby ultimately affecting olfactory-driven behaviours. We describe the molecular effects of 10 insect repellents and a pyrethroid insecticide with known repellent activity on two highly specific Aedes aegypti (Diptera: Culicidae) ORs, AaOR2 + AaOR7 and AaOR8 + AaOR7, exquisitely sensitive to key mosquito attractants indole and (R)-(−)-1-octen-3-ol, expressed in oocytes of Xenopus (Anura: Pipidae). Our study demonstrates that insect repellents can both inhibit odorant-evoked currents mediated by ORs and independently elicit currents in the absence of odorants. All of the repellents had effects on one or both ORs; most of these compounds were selective inhibitors and showed a high degree of specificity in their capacity to activate the two ORs. These results show that a range of insect repellents belonging to structurally diverse chemical classes modulate the function of mosquito ORs through multiple molecular mechanisms.