Attraction of phlebotomine sandflies to volatiles from skin odors of individuals residing in an endemic area of tegumentary leishmaniasis

Abstract

Background: Many studies have investigated what could attract insects of medical importance and a crucial role has lately been attributed to human skin odors. Most of these researches have been concerned with mosquitoes, e.g., vectors of dengue and malaria. Little is known about volatile organic compounds (VOCs) from human skin odors and their effects on leishmania vectors.

Objective: The present study aimed to identify the VOCs from human skin that can be attractive to female anthropophilic phlebotomine sandflies.

Results: Forty-two VOCs were identified from skin odors of 33 male volunteers, seven of which were tested in wind tunnel assays employing field-captured phlebotomine sandflies (75.4% identified as Lutzomyia intermedia). Hexane and (E)-oct-3-en-1-ol (octenol) were used as negative and positive controls, respectively. 2-Phenylacetaldehyde (hereafter called phenylacetaldehyde), 6-methylhept-5-en-2-one (also known as sulcatone), nonadecane and icosane were found to activate female phlebotomine sandflies, but only phenylacetaldehyde, 6-methylhepten-5-en-2-one and icosane elicited attraction responses.

Conclusions: These results suggest that phenylacetaldehyde, 6-methylhepten-5-en-2-one and icosane may be suitable candidates for attractiveness experimentation in the field which can be an important tool to develop strategies concerning human beings protection against phlebotomine sandflies bites and consequently against leishmaniasis.

Fig 1

(A) Wind tunnel with a thermohygrometer (a) monitoring temperature and humidity inside the tunnel; (b) Platform to secure the VOC-embedded filter paper; (c) Detail showing the platform with the phlebotomine sandfly release chamber; (B) Wind tunnel under red light illumination with a mini tunnel (black arrow) consisting of white netting.

Fig 2. Distribution of the volatile organic compounds identified from the collected human leg hair samples, according to their organic chemical functions.

Fig 3. Activation response of captured female phlebotomine sandflies expressed as percentage of activated insects in wind tunnel assays.

Hexane was used as a negative control (white bars). * indicates a significant difference in pairwise comparison (p<0.05); ** indicates p<0.01; *** indicates p<0.0001.

Fig 4. Attraction response of captured female phlebotomine sandflies expressed as percentage of attracted insects in wind tunnel assays.

Hexane was used as a negative control (white bars). * indicates a significant difference in pairwise comparison (p<0.05); ** indicates p<0.01; *** indicates p<0.0001.