Aedes aegypti Mosquitoes Detect Acidic Volatiles Found in Human Odor Using the IR8a Pathway

Curr Biol. 2019 Apr 22;29(8):1253-1262.e7. doi: 10.1016/j.cub.2019.02.045. Epub 2019 Mar 28.


Mosquitoes use olfaction as a primary means of detecting their hosts. Previously, the functional ablation of a family of Aedes aegypti olfactory receptors, the odorant receptors (ORs), was not sufficient to reduce host seeking in the presence of carbon dioxide (CO2). This suggests the olfactory receptors that remain, such as the ionotropic receptors (IRs), could play a significant role in host detection. To test this, we disrupted the Ir8a co-receptor in Ae. aegypti using CRISPR/Cas9. We found that Ir8a mutant female mosquitoes are not attracted to lactic acid, a behaviorally active component of human sweat, and they lack odor-evoked responses to acidic volatiles. The loss of Ir8a reduces mosquito attraction to humans and their odor. We show that the CO2-detection pathway is necessary but not sufficient for IR8a to detect human odor. Our study reveals that the IR8a pathway is crucial for an anthropophilic vector mosquito to effectively seek hosts. VIDEO ABSTRACT.

Keywords: Aedes aegypti, carbon dioxide; IR8a; Orco; host seeking; human sweat; ionotropic receptors; lactic acid; mosquito; olfaction.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aedes / physiology*
  • Animals
  • Chemotaxis*
  • Female
  • Humans
  • Insect Proteins / genetics*
  • Insect Proteins / metabolism
  • Male
  • Odorants*
  • Receptors, Ionotropic Glutamate / genetics*
  • Receptors, Ionotropic Glutamate / metabolism
  • Volatile Organic Compounds / metabolism*


  • Insect Proteins
  • Receptors, Ionotropic Glutamate
  • Volatile Organic Compounds