Abstract—Several populations of Culex pipiens sensu latu mosquitoes, a vector of mosquito-born flaviviruses such as west nile virus, have developed resistance to pyrethroids in the United States. To design and then institute resistance monitoring, mitigation, and management strategies, knowledge of the mechanisms of resistance will be required. Preliminary investigations conducted on Culex pipiens s.l. populations in California and Southern Africa strongly suggest that this resistance is mediated by enzymatic detoxification and/or target-site sensitivity. The aims are to determine permethrin resistance levels in first generation progeny of colonies collected Culex spp. from various regions of California and evaluate the levels of detoxification enzyme [esterase and glutathione S-transferase (GST)] and improve diagnostic Knockdown resistance (kdr) in F1 progeny of Culex spp. mosquitoes with confirmed permethrin resistance. In this study, mosquitoes in the Culex pipiens complex were collected at various sites throughout California and tested for esterase, GST, and kdr activities. The esterase, GST, and kdr activities were compared to the corresponding activities found in a pyrethroid-sensitive laboratory strain Culex quinquefasciatus(CQ1). A correlation was found between elevated esterases activities and kdr assay indicating that further investigation should be done to figure out the potential role of enzyme detoxification and kdr assay in conceding resistance to pyrethroids class.

Index Terms—Culex pipiens, pyrethroids, knockdown resistance (kdr), pesticides resistance.

M. A. I. Ahmed is with Plant Protection Department, Faculty of Agriculture, Assiut University, Assiut, Egypt (e-mail: maiaf2000@yahoo.com).
A. Cornel is with the Department of Entomology, University of California, Davis, Mosquito Control Research Laboratory, 9240 S Riverbend Avenue, Parlier, CA 93648. USA (e-mail: CORNEL@uckac.edu).
B. Hammock is with Entomology, UCD& Cancer Center UCD Medical Center, Director of NIEHS-UCD Superfund Basic Research Program, and PI NIH Biotechnology Training Program, University of California, Davis, CA 95616 USA (e-mail: bdhammock@ucdavis.edu).

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Cite: M. A. I. Ahmed, A. Cornel, and B. Hammock, "Monitoring of Insecticide Resistance of Culex pipiens (Diptera: Culicidae) Colonies-Collected from California," International Journal of Environmental Science and Development vol. 3, no. 4, pp. 346-349, 2012.