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

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.

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.

The canine VOC profile was predominantly composed of aldehydes, with hexanal and nonanal eliciting the strongest antennal responses in P. perniciosus.

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.