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Multiple activities of insect repellents on odorant receptors in mosquitoes

Authors

  • J. D. BOHBOT,

    1. Invasive Insect Biocontrol and Behavior Laboratory, Plant Sciences Institute, U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, MD, U.S.A.
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  • L. FU,

    1. Section on Molecular Morphogenesis, Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD, U.S.A.
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  • T. C. LE,

    1. Invasive Insect Biocontrol and Behavior Laboratory, Plant Sciences Institute, U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, MD, U.S.A.
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  • K. R. CHAUHAN,

    1. Invasive Insect Biocontrol and Behavior Laboratory, Plant Sciences Institute, U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, MD, U.S.A.
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  • C. L. CANTRELL,

    1. Natural Products Utilization Research Unit, USDA-ARS, University of Mississippi, University, MS, U.S.A.
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  • J. C. DICKENS

    Corresponding author
    1. Invasive Insect Biocontrol and Behavior Laboratory, Plant Sciences Institute, U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, MD, U.S.A.
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Dr Joseph C. Dickens, Invasive Insect Biocontrol and Behavior Laboratory, Plant Sciences Institute, Beltsville Agricultural Research Center, Building 007, Room 030, 10300 Baltimore Avenue, Beltsville, MD 20705, U.S.A. Tel.: +1 301 504 8957; Fax: +1 301 504 6580; E-mail: joseph.dickens@ars.usda.gov

Abstract

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.

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