Evaluation of Insecticides Resistance in Culex Mosquitoes to DDT, Deltamethrin, Permethrin and PBO (Synergy) in Gombe Metropolis, Nigeria

Abstract

Aims: To evaluate the resistance of Culex mosquitoes in Zagaina, Gombe State, to commonly used insecticides, providing insights for managing insecticide resistance in disease vector control. Study Design: Cross-sectional susceptibility bioassay study. Place and Duration of Study: This study was conducted Gombe State University Malaria Vector Sentinal Laboratory over three months (October-December). Methodology: Approximately 600 Culex mosquito larvae and pupae were collected from blocked and improperly maintained drainages in Zagaina community using standard dipping techniques. The collected mosquitoes were reared to adulthood in an insectary at Gombe State University. Female Culex mosquitoes were separated and subjected to a time-course exposure bioassay using CDC bioassay tubes, following WHO guidelines for evaluating insecticide resistance in vectors. WHO-impregnated papers were used to test susceptibility to four insecticides: DDT, Permethrin, Deltamethrin, and Piperonyl Butoxide (PBO). The knockdown rate was assessed followed by Mortality rate of 24 hours post-exposure, with no correction needed as control mortality was zero. Results: High resistance was observed across all tested insecticides, with mortality rates of 15% for DDT, 7% for Permethrin, 65% for Deltamethrin, and 69% for PBO. These results indicate that Culex mosquitoes in Zagaina community exhibit significant resistance to DDT and Permethrin, moderate resistance to Deltamethrin, and lower resistance to PBO. Conclusion: The  insecticide resistance observed in Culex mosquitoes indicate an urgent need to investigate the genetic or metabolic mechanisms of resistance. Monitoring resistance patterns over time is essential for developing effective vector control strategies to combat mosquito-borne diseases.