title: L-lactic acid: a human-signifying host cue for the anthropophilic mosquito Anopheles gambiae.
abstract: Using a dual-choice olfactometer, the role of L-lactic acid was investigated in relation to host-seeking and selection by female Anopheles gambiae Giles sensu stricto (Diptera: Culicidae) mosquitoes in a Y-tube bioassay. L-lactic acid alone was not attractive, but it significantly augmented the attractiveness of CO2, skin odour and skin-rubbing extracts from humans and other vertebrates. Comparing the left and right index fingers of the same person, one could be made more attractive than the other by adding L-lactic acid to the air stream over that finger. The difference in L-lactic acid concentration between the two air streams offered to the mosquitoes fell within the natural range of variation emanating from a human hand, suggesting that L-lactic acid modulates intraspecific host selection by An. gambiae. Analysis of skin rubbings from various vertebrates (carnivores, chickens, primates, rodents, ungulates) indicated that humans have uniquely high levels of L-lactic acid on their skin. Tests with extracts of skin rubbings from cows and humans, with and without added L-lactic acid, suggest that naturally lower levels of L-lactic acid contribute to the lesser attractiveness of non-humans to An. gambiae s.s.
authors.affiliation: Department of Entomology, University of California, Riverside, USA.
authors.forename: T
authors.initials: T
authors.lastname: Dekker
authors.forename: B
authors.initials: B
authors.lastname: Steib
authors.forename: R T
authors.initials: RT
authors.lastname: Cardé
authors.forename: M
authors.initials: M
authors.lastname: Geier
mesh_terms: D000818:Animals; D000852:Anopheles / Q000502:physiology*; D002245:Carbon Dioxide / Q000737:chemistry / Q000378:metabolism; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000737:chemistry* / Q000378:metabolism; D009812:Odorants; D014714:Vertebrates / Q000378:metabolism* / Q000469:parasitology
chemical_list: D002245:Carbon Dioxide; D019344:Lactic Acid