Abstract

Host seeking in the yellow fever mosquito, Aedes aegypti, and the African malaria mosquito, Anopheles coluzzii, relies on specific and generic host-derived odorants. Previous analyses indicate that the behavioral response of these species depends differentially on the presence of carbon dioxide (CO2) and other constituents in human breath for activation and attraction. In this study, we use a flight tube assay and electrophysiological analysis to assess the role of acetone, a major component of exhaled human breath, in modulating the behavioral and sensory neuronal response of these mosquito species, in the presence and absence of CO2. When presented alone at ecologically relevant concentrations, acetone increases attraction in Ae. aegypti, but not in An. coluzzii. Moreover, in combination with CO2, human breath-equivalents of acetone ranging between 0.1 and 10 ppm reproduces a behavioral response similar to that observed to human breath in host-seeking Ae. aegypti, but not in An. coluzzii. Acetone does, however, reduce attraction to CO2 in An. coluzzii, when presented at a higher concentration of 10 ppm. We identify the capitate peg A neuron of the maxillary palp of both species as a dual detector of CO2 and acetone. The sensory response to acetone, or binary blends of acetone and CO2, reflects the observed behavioral output in both Ae. aegypti and An. coluzzii. We conclude that host recognition is contextual and dependent on a combination of ecologically relevant odorants at naturally occurring concentrations that are encoded, in this case, by differences in the temporal structure of the neuronal response. This information should be considered when designing synthetic blends for that optimally attract mosquitoes for monitoring and control.

Highlights

  • IntroductionTo identify new vector control measures to prevent the transmission of these diseases, the odor-mediated host-seeking behavior of mosquitoes has been put under scrutiny [2]

  • The behavioral response of Ae. aegypti and An. coluzzii to human breath relies on the presence of CO2 [18, 33, this study] and is differentially modulated by acetone

  • While acetone enhances the behavioral response of Ae. aegypti, in both the presence and absence of CO2, it decreases the behavioral response of An. coluzzii in the presence of CO2

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Summary

Introduction

To identify new vector control measures to prevent the transmission of these diseases, the odor-mediated host-seeking behavior of mosquitoes has been put under scrutiny [2]. This behavior is heavily dependent on specific and generic host-derived volatile cues, which when presented in an accurate blend elicit a sequence of behaviors, including activation, attraction and landing [3,4,5,6]. An increased understanding of odor blend perception in mosquitoes is pertinent for the development of synthetic blends that support monitoring and control of host-seeking mosquitoes

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