Molecular and metabolic resistance mechanisms in insecticides resistant Culex quinquefasciatus population from Lagos, Nigeria

Abstract

Background: The control and management of mosquito-borne diseases heavily rely on the use of insecticide-based measures, but the emergence and spread of insecticide resistance have been a challenge and led to a significant setback in recent gains against the control of mosquito-borne diseases. Here, we as-sessed the susceptibility of Cx. quinquefasciatus to different classes of neurotoxic insecticides and deter-mined the possible resistance mechanisms. Methodology: Culex mosquitoes were collected from Kosofe, Alimosho, Ibeju-Lekki, and Badagry Lo-cal Government Areas (LGAs) of Lagos State. Adult females were exposed to permethrin, Bendiocarb, and piperonyl butoxide (PBO) synergized assays using WHO protocols. Resistance mechanisms were assessed using molecular and biochemical techniques. Results: Resistance to permethrin in Cx. quinquefasciatus was recorded in all the study locations, with 24-hour mortality ranging from 5% to 89%. Resistance to bendiocarb was also recorded in Alimosho (7%) and Kosofe (19%) LGAs, while possible resistance (96%) in Ibeju-Lekki LGA. PBO synergists significantly reduced the KDT50 and KDT95 of the synergized bioassays compared to the non-synergized bioassay. Heterozygote-resistant Ace1R gene was detected in Cx. quinquefasciatus popula-tion from Kosofe and Alimosho, kdr L1014S and L1014F were not detected in this study. Conclusion: The activities of Cytochrome P450 monooxygenase and glutathione S-transferase detoxify-ing enzymes negatively correlate with 24-hour percentage mortality of Cx. quinquefasciatus. Resistance reported in Cx. quinquefasciatus to multiple classes of insecticides may result in difficulty controlling lymphatic filariasis in these areas.