Submitted to: Journal of Medical Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/19/2005
Publication Date: 3/1/2006
Citation: Allan, S.A., Bernier, U.R., Kline, D.L. 2006. Laboratory evaluation of avian odors for mosquito (diptera:culicidae) attraction. Journal of Medical Entomology. 43(2):225-231. Interpretive Summary: Culex mosquitoes are the most important vectors of West Nile virus and St. Louis encephalitis in the United States. Trapping is critical in the surveillance of vector abundance and disease presence and this often guides subsequent control effects. Traps using standard attractants (i.e. carbon dioxide) are generally of limited value for trapping Culex. These mosquitoes feed readily on birds, however, relatively little is known about the chemicals that mosquitoes use to locate birds. In this study, conducted at USDA, ARS, Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida, the responses of three species of Culex to odors associated with birds were examined. All Culex mosquitoes responded strongly to chickens and relatively little to a human arm. Feathers were moderately attractive and attraction was enhanced in the presence of carbon dioxide. None of the previously identified bird odors tested were attractive. Hexane extracts of feathers, however, were attractive to Culex and will form the basis for the subsequent identification, testing and use of bird odors for trapping for Culex mosquitoes.
Technical Abstract: Attraction of Culex quinquefasciatus, Culex tarsalis, Culex nigripalpus and Aedes aegypti to avian and other host odors was investigated in a dual-port olfactometer. While attraction to a human arm was high for Ae. aegypti (> 80%) and low for all Culex spp. (< 25%), all species responded similarly to a chicken (55.3-73.6%). Responses of Ae. aegypti, Cx. quinquefasciatus and Cx. nigripalpus to feathers were low (< 20%) but significantly greater than to the controls. There was no difference in attraction of Cx. tarsalis to feathers or controls. Responses to CO2 (5 ml/min) were low for all species (< 15%) except Cx. tarsalis which had moderate responses (24.5%). When feathers were combined with CO2, attraction appeared to be additive or less for all species except for Cx. tarsalis which had a 3-fold increase in attraction. The CO2/feather treatments were less attractive than a chicken for all species. When olfactometer assays were extended from 3 to 20 min, responses by Ae aegypti significantly increased to a chicken and CO2. Attraction of Cx. quinquefasciatus was significantly greater to chickens, CO2 and feathers and longer assay times were subsequently used for evaluating compounds and extracts. None of the volatile compounds previously identified from feathers or uropygial glands were attractive. Both feather-rubbed cotton balls and hexane extracts of feathers were attractive in the olfactometer and as attractive as feathers, while ether extracts were not attractive. Feathers clearly contribute to the attraction of host-seeking Culex spp. and future studies will focus on identification of the attractant compounds.