The chemical code for attracting Culex mosquitoes

Authors: SPANOUDIS, CHRISTOS - Aristotle University Of Thessaloniki; WONDOWSEN, BETELEHEM - Addis Ababa University; ISBERG, ELIN - Swedish University Of Agricultural Sciences; ANDREADIS, STEFANOS - Swedish University Of Agricultural Sciences; Kline, Daniel - Dan; BIRGERSSON, GORAN - Swedish University Of Agricultural Sciences; IGNELL, RICKARD - Swedish University Of Agricultural Sciences

Submitted to: Frontiers in Ecology and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/12/2022
Publication Date: 8/11/2022
Citation: Spanoudis, C.G., Wondowsen, B., Isberg, E., Andreadis, S.S., Kline, D.L., Birgersson, G., Ignell, R. 2022. The chemical code for attracting Culex mosquitoes. Frontiers in Ecology and Evolution. https://doi.org/10.3389/fevo.2022.930665.
DOI: https://doi.org/10.3389/fevo.2022.930665

Interpretive Summary: This research was conducted as part of a larger effort to understand how female mosquitoes locate and distinguish between potential hosts in order to obtain a blood meal required to produce eggs. An ARS scientist was invited to participate in this international, multi-institutional, collaborative project spearheaded by scientists from the Disease Vector Group, Unit for Chemical Ecology, Swedish University of Agricultural Sciences. This project specifically mosquitoes in the genus Culex, which transmit West Nile virus. Using a combination of tools bioactive, volatile organic compounds were isolated from ch icken emanates and formulated into a blend. Through a combination of laboratory and field experiments this blend was shown to be effective in attracting female Culex mosquitoes. These collaborative efforts lay an important foundation for future control interventions targeting these disease vector mosquitoes.

Technical Abstract: Mosquitoes use chemical codes to locate and discriminate among vertebrate hosts to obtain a blood meal. Recent advances have allowed for the identification of the chemical codes used by mosquitoes to locate and discriminate humans from other vertebrate hosts. Humans are incidental ‘dead-end’ hosts for the West Nile virus, which is maintained in an enzootic cycle, primarily through its transmission between infected birds by Culex mosquitoes. Host-seeking Culex mosquitoes are attracted to the odour of chicken, which are used in sentinel traps to monitor West Nile virus transmission. Using combined gas chromatography and electroantennography and mass spectrometry we identify a blend of volatile organic compounds present in chicken emanates, including mostly salient bioactive compounds previously identified in human emanates. When released in their natural ratios, and at ecologically relevant rates, this blend elicits behavioural responses of Culex pipiens molestus and Culex quinquefasciatus similar to that to the natural chicken odour. Tested under field conditions, this blend differentially attract Culex mosquitoes, and other species of mosquitoes that include birds within their host range. This study provides evidence for conserved chemical codes for resource location by mosquitoes, and highlights the intricate role of CO2 for host-seeking mosquitoes. The identification of conserved chemical codes, which drive innate preference behaviours that are fundamental for survival and reproduction, provides important substrates for future control interventions targeting disease vector mosquitoes.