KAIROMONES IN HUMAN SWEAT ACTIVE ON FEMALE AND MALEANOPHELINE MOSQUITOES.
J. Ziesmann and K. Haberkorn
Max-Planck-Institut für Verhaltensphysiologie, Seewiesen, Postfach1564, 92305 Starnberg, Germany.

Anopheline mosquitoes are dangerous vectors of malaria, especially thefemales of Anopheles gambiae that have a preference for humans ashosts and a long life span. Vertebrate metabolites like CO₂, lactic acid, 1-octen-3-ol and p-cresol as well as a number of short-chainfatty acids have been identified in human sweat extracts and are electrophysiologicallyactive (Cork A, Park K.C. (1996) Med. Vet. Entomol. 10: 269-276). In ourfirst attempt to identify the key stimuli among the multitude of humanproduced chemicals that mediate this host preference in the females wecompare the electrophysiological responses of the female and male mosquitoesto know chemicals as well as the responses to extracts (pentane, diethyletheror methanol) of human sweat. The extracts were gas chromatographicallyanalysed and coupled GC-EAGs were obtained. The electrophysiological activitiesof the extract suggest that the most active chemicals have intermediatepolarity. Males as well as females show electrophysiological responsesto sweat extracts, p-cresol and 1-octen-3-ol. Comparison of dose-responsecurves shows, that males need 10 to 100 fold higher concentrations as femalesfor comparable EAG responses. Single unit recordings to identify the olfactoryspecificity of the antennal sensilla have been started. We hope to correlatethese specificities with the occurrence of kairomone-specific odorant-bindingproteins in the sensilla.