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Commonly used insect repellents hide human odors from Anopheles mosquitoes
Journal article   Open access   Peer reviewed

Commonly used insect repellents hide human odors from Anopheles mosquitoes

Ali Afify, Joshua F. Betz, Olena Riabinina, Chloé Lahondère and Christopher J. Potter
Current biology, v 29(21), pp 3669-3680.e5
04 Nov 2019
PMID: 31630950
url
https://doi.org/10.1016/j.cub.2019.09.007View
Published, Version of Record (VoR) Open

Abstract

The mode of action for most mosquito repellents is unknown. This is primarily due to the difficulty in monitoring how the mosquito olfactory system responds to repellent odors. Here, we used the Q-system of binary expression to enable activity-dependent Ca 2+ imaging in olfactory neurons of the African malaria mosquito Anopheles coluzzii . This system allows neuronal responses to common insect repellents to be directly visualized in living mosquitoes from all olfactory organs including the antenna. The synthetic repellents DEET and IR3535 did not activate Anopheles Odorant Receptor Co-Receptor (Orco) expressing olfactory receptor neurons (ORNs) at any concentration, while picaridin weakly activated ORNs only at high concentrations. In contrast, natural repellents ( i.e. lemongrass oil and eugenol) strongly activated small numbers of ORNs in the Anopheles mosquito antennae at low concentrations. We determined that DEET, IR3535, and picaridin decrease the response of Orco expressing ORNs when these repellents are physically mixed with activating human-derived odorants. We present evidence that synthetic repellents may primarily exert their olfactory mode of action by decreasing the amount of volatile odorants reaching ORNs. These results suggest that synthetic repellents disruptively change the chemical profile of host scent signatures on the skin surface rendering humans invisible to Anopheles mosquitoes. The olfactory mode of action for mosquito repellents is unclear. Afify et al genetically engineered Anopheles mosquitoes to reveal odor-induced activities in olfactory neurons. Natural repellents activated olfactory neurons, while synthetic repellents did not. Synthetic repellents instead likely reduce attraction to humans by decreasing the amount of odorants reaching the mosquito.

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Collaboration types
Domestic collaboration
International collaboration
Web of Science research areas
Biochemistry & Molecular Biology
Biology
Cell Biology
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