Local Variability in Permethrin Susceptibility of Anopheles Mosquitoes in Batagarawa, Katsina State, Nigeria

Abstract

Malaria has been one of the major public health challenge in Nigeria, with vector control heavily reliant on pyrethroid-based interventions such as long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). Widespread insecticide resistance in Anopheles mosquitoes threatens these gains, yet locality-specific resistance patterns remain poorly understood. This study assessed locality-based variations in the susceptibility of Anopheles mosquitoes to permethrin in Batagarawa Local Government Area (LGA), Katsina State, Northwestern Nigeria. We hypothesized that no significant difference exists between localities in mosquito resistance or susceptibility to permethrin. Anopheles larvae were collected from five localities, reared under controlled insectary conditions, and tested using WHO standard tube bioassays with 0.75% permethrin. Knockdown times (KDT₅₀, KDT₉₅) and 24-hour mortality were recorded and analyzed. Breeding habitats showed broadly similar physicochemical characteristics, with minor differences in pH and temperature. Knockdown dynamics varied significantly across sites (p < 0.05), but 24-hour mortality ranged from 7% to 39%, far below the WHO threshold for susceptibility (≥98%). All populations exhibited confirmed resistance, with no operationally meaningful differences between localities. The findings confirm widespread permethrin resistance in Anopheles populations across Batagarawa LGA, undermining the effectiveness of pyrethroid-based vector control tools. It is therefore recommended that there is need for transitioning to next-generation LLINs, diversifying IRS insecticides, expanding resistance surveillance with molecular diagnostics, and integrating ecological management strategies to sustain malaria control efforts in Northern Nigeria.