title: Behavioral response of the malaria mosquito, Anopheles gambiae, to human sweat inoculated with axilla bacteria and to volatiles composing human axillary odor.
abstract: The responses of Anopheles gambiae Giles sensu stricto (Diptera: Culicidae) to odors from male and female axillary sweat incubated with human axilla bacteria were recorded in a dual-choice olfactometer. Staphylococcus epidermidis was selected for its low odor-producing pattern, Corynebacterium jeikeium for its strong Nα-acylglutamine aminoacylase activity liberating carboxylic acids including (R)/(S)-3-hydroxy-3-methylhexanoic acid (HMHA) and Staphylococcus haemolyticus for its capacity to liberate sulfur-containing compounds including (R/S)-3-methyl-3-sulfanylhexan-1-ol (MSH). Anopheles gambiae behavioral responses were evaluated under (i) its responsiveness to take off and undertake sustained upwind flight and (ii) its discriminating capacity between the two olfactometer arms bearing a test odor in either one or both arms. Experiments were conducted in the presence of carbon dioxide pulses as a behavioral sensitizer. Anopheles gambiae clearly discriminated for the olfactometer arm conveying odor generated by incubating any of the three bacteria species with either male or female sweat. Whereas An. gambiae did not discriminate between male and female sterile sweat samples in the olfactometer, the mosquito consistently showed a preference for male sweat over female sweat incubated with the same bacterium, independent of the species used as inoculum. Sweat incubated with C. jeikeium rendered mosquitoes particularly responsive and this substrate elicited the strongest preference for male over female sweat. Tested on their own, neither HMHA nor MSH elicited a clear discriminating response but did affect mosquito responsiveness. These findings serve as a basis for further research on the odor-mediated anthropophilic host-seeking behavior of An. gambiae.
authors: Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland and.
authors: Jérôme
authors: J
authors: Frei
authors: Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland and.
authors: Thomas
authors: T
authors: Kröber
authors: Corporate Research and Development Division, Firmenich S.A., PO Box 239, 1211 Geneva 8, Switzerland.
authors: Myriam
authors: M
authors: Troccaz
authors: Corporate Research and Development Division, Firmenich S.A., PO Box 239, 1211 Geneva 8, Switzerland.
authors: Christian
authors: C
authors: Starkenmann
authors: Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland and patrick.guerin@unine.ch.
authors: Patrick M
authors: PM
authors: Guerin
mesh_terms: D000818:Animals; D000852:Anopheles / Q000502:physiology*; D001365:Axilla / Q000382:microbiology*; D001419:Bacteria / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D009812:Odorants / Q000032:analysis*; D010675:Pheromones / Q000502:physiology*; D013542:Sweat / Q000737:chemistry*
chemical_list: D010675:Pheromones; C010411:insect attractants
keywords: 
  Anopheles gambiae
  ; (R)/(S)-3-hydroxy-3-methylhexanoic acid; (R/S)-3-methyl-3-sulfanylhexan-1-ol; axilla bacteria; human sweat; malaria mosquito