A simplified system for the detection of antennal responses to host-borne volatile organic compounds in sand flies

Background: Phlebotomus (Larroussius) perniciosus (Diptera: Psychodidae) is the most common and predominant vector of Leishmania infantum in the Western Mediterranean region. Volatile organic compounds (VOCs) produced by vertebrates are important cues affecting the behaviour of blood-feeding insects. Generally, the identification of putative behaviourally active VOCs involves three distinct phases: extraction, chemical characterization and chemoreceptivity evaluation using electrophysiological techniques. Here, we present a simplified gas chromatography-mass spectrometry-electroantennographic detection (GC-MS-EAD) setup adapted for screening bioactive compounds in sand flies, in which the chemical identification and antennal responses are recorded simultaneously. Methods: The method integrates: (i) a flow-splitter that balances the flow rate of the two outgoing streams, (ii) GC columns with different lengths and diameters in the two sections splitter-MS and splitter-EAD and (iii) an antennal signal amplifier. The GC-MS-EAD analysis was applied to headspace solid-phase microextraction (HS-SPME) extracts from a healthy dog, and antennal responses were recorded in female P. perniciosus sand flies. Results: The canine VOC profile was predominantly composed of aldehydes, with hexanal and nonanal eliciting the strongest antennal responses in P. perniciosus. Conclusions: This simplified GC-MS-EAD system shows promise for broader application in the study of host-vector interactions. Its use across different host-vector pairs may enhance our understanding of these relationships and inform the development of strategies for integrated vector monitoring and control.