Application site and mosquito age influences malathion- and permethrin-induced mortality in Culex quinquefasciatus

Authors: Aldridge, Robert; KAUFMAN, PHILLIP - University Of Florida; BLOOMQUIST, JEFFREY - University Of Florida; GEZAN, SALVADOR - University Of Florida; Linthicum, Kenneth - Ken

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2017
Publication Date: 9/6/2017
Citation: Aldridge, R.L., Kaufman, P.E., Bloomquist, J.R., Gezan, S.A., Linthicum, K. 2017. Application site and mosquito age influences malathion- and permethrin-induced mortality in Culex quinquefasciatus. Journal of Medical Entomology. https://doi.org/10.1093/jme/tjx160.

Interpretive Summary: We evaluated the mortality caused by 2 commonly used insecticides on female mosquitoes of different ages. At exposure rates equal to those typically found in mosquito aerosol sprays used in professional mosquito control applications mortality was highest in the youngest (<1 day old) and oldest (14 days old) mosquitoes. Mosquitoes ages 3 and 7 days old survived the best. Older mosquitoes are most likely to transmit human diseases because the diseases have time to grow in the mosquito and invade the salivary glands of the mosquito, a requirement for disease transmission to occur during feeding. Mosquito control operations targeted on stopping disease transmission should be effective in killing the older mosquitoes which pose the greatest threat to disease transmission.

Technical Abstract: Concentrations of malathion and permethrin typical in droplets generated from ultra-low volume and low volume applications were evaluated for efficacy against multiple-aged Culex quinquefasciatus Say, using a topical bioassay. Although during mosquito control operations insecticide droplets will impinge on many exoskeletal body regions and a range of ages of mosquitoes in a population, traditional mosquito topical bioassays in the laboratory focus pesticide application to the mesothoracic pleural or dorsal regions across an average mosquito age (e.g., 3-7 days). Our results document non-uniform insecticide sensitivity across body regions at ages not previously assessed in mosquitoes (teneral and 14-d-old). We expect our findings to influence the topical bioassay process, illustrating the difference in mosquito body regions and ages that ultimately may explain insecticide effectiveness wherever droplets impinge upon the mosquito body during field control applications.