How Local Mosquito Control Methods Influence the Spread of Vector-borne Diseases: The Impact of Maricopa County Fogging on Levels of Insecticide Resistance in Culex quinquefasciatus Mosquitoes

This study aimed to assess the impact of local insecticide fogging procedures (carried out by Maricopa County Vector Control) on the development of insecticide resistance mechanisms in field populations of Cx. quinquefasciatus mosquitoes. To address this aim, Cx. quinquefasciatus eggs were collected from six field sites ranging from levels of high, medium, and no exposure to insecticides. The collected eggs were then reared, and adult mosquitoes underwent topical application bioassays to determine if deltamethrin resistance levels were associated with the fogging frequency of the field site from which the eggs were collected. The results suggest the presence of pyrethroid resistance amongst all field populations in comparison to an insecticide susceptible strain of Culex mosquito. However, the deltamethrin resistance levels of mosquitoes from each site were not significantly different. These results suggest that, outside of government insecticide fogging, there are other sources acting as selective pressures for resistance mechanisms in local Cx. quinquefasciatus mosquito populations.