Location: Mosquito and Fly Research Unit
Title: Laboratory evaluation of human-associated odors on attraction of Culex spp. (Diptera:Culicidae) Authors
Submitted to: Journal of Vector Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 15, 2010
Publication Date: October 1, 2010
Citation: Allan, S.A., Bernier, U.R., Kline, D.L. 2010. Laboratory evaluation of human-associated odors on attraction of Culex spp. (Diptera:Culicidae). Journal of Vector Ecology. 35:318-324. Interpretive Summary: With the recent introduction and subsequent spread of West Nile across the United States, accurate trapping methods for Culex mosquitoes are critical. These are necessary for detection of virus and determination of risk and for making informed mosquito control decisions. An important component of trapping is the attractant used and many attractants developed are based on odors from humans. In particular, lactic acid which is present abundantly on human skin has been incorporated into commercial lures. In this study, conducted at USDAs Center for Medical, Agricultural and Veterinary Entomology (CMAVE) in Gainesville (Florida), the responses of three species of Culex known to be vectors of West Nile virus were tested against different formulations of lactic acid. Lactic acid was a moderate attractant for one species of Culex and was repellent for two other species of Culex. These results are important for determination of the appropriate attractants for use with different Culex species and will improve our efficacy of mosquito trapping for disease and population surveillance.
Technical Abstract: The role of L-lactic acid (lactic acid) and several other human-associated compounds were evaluated for attraction of Culex nigripalpus Theobald, Culex quinquefasciatus Say, Culex tarsalis Coquillett and Aedes aegypti (L.) in the laboratory using a dual-port olfactometer. Previous studies indicated that lactic acid may mediate attraction of anthropophilic species to humans and conversely deter zoophilic species. When lactic acid was combined with chicken odor, attraction was similar for Ae. aegypti and Cx. nigripalpus, increased for Cx. quinquefasciatus and reduced for Cx. tarsalis. When lactic acid was combined with hand odor, attraction of Ae. aegypti and Cx. tarsalis did not change and attraction of Cx. nigripalpus and Cx. quinquefasciatus decreased. The addition of lactic acid to CO2 enhanced attraction of Ae. aegypti and Cx. quinquefasciatus but reduced attraction of Cx. nigripalpus and Cx. tarsalis compared to attraction to CO2 alone. Use of commercially formulated slow-release lactic acid baits in conjunction with CO2 resulted in a similar trend except for no difference in response by Cx. nigripalpus. A blend of lactic acid, acetone, and dimethyl disulfide was attractive to Ae. aegypti (63.4%) but elicited low responses by all Culex spp. (1.3-26.8%). Addition of the blend enhanced attraction to CO2 of Ae. aegypti and Cx. quinquefasciatus but decreased attraction of Cx. nigripalpus and Cx. tarsalis. The mixture of compounds plus CO2 was similar in attraction to a hand for Ae. aegypti and Cx. quinquefasciatus. In an evaluation of individual compounds associated with humans, only Ae. aegypti was attracted to acetone and lactic acid, only Cx. quinquefasciatus was attracted to ammonia, all species were attracted to dichloromethane and only Ae. aegypti and Cx. quinquefasciatus responded to dimethyl disulfide.