Preliminary evidence of Rhodnius prolixus (Hemiptera: Triatominae) attraction to human skin odour extracts.

Host-seeking behaviour displayed by the haematophagous triatomine Rhodnius prolixus Stål, 1859 is influenced by different cues involving heat, moisture and odours. Concentrations of volatile odours present in human sweat and breath that activate, attract or non-attract triatomines were tested behaviourally with a double choice olfactometer in adults of R. prolixus. Attraction of a mixture of substances carried by a controlled air-stream was established and compared with volatiles from human extracts obtained by rubbing face, hands or feet. Volatiles from face and feet extracts showed a higher attraction to triatomines than hand extracts. Only volatiles from face extracts attracted significantly more insects than the other extracts when they were compared with the mixture. Face extract attractiveness was reduced at least for 1h after treatment with an anti-bacterial gel. Our experiments not only confirm that the mixture of compounds was attractive, but also suggest that probably microflora compounds present mainly in face extracts improve its attractiveness. Triatomines preference to bite on human face has epidemiological implications on vectorial Chagas disease transmission by increasing Trypanosoma cruzi contact with mucosal tissue.