Pyrethroid resistance in the Sudan Savannah Region in Nigeria: a study of the resistance profile and resistance mechanism of Anopheles populations from Hadejia Town in Jigawa State

Abstract

Insecticide-based control measures are key strategies against malaria vectors, and pyrethroid is the only recommended class of insecticide for public health use. The work aimed at determining the pyrethroid resistance in Anopheline mosquitoes and the frequency of the knockdown resistance (kdr) gene determinant. Larval samples were collected from two sites in Hadejia Town, Jigawa State in April 2020 and November/December 2020, and reared to adulthood in Bayero University Kano Biochemistry's insectary. Samples were identified by morphological and molecular techniques. Three to five-day-old adult mosquitoes were exposed to standard concentrations of 0.75% permethrin and 0.05% deltamethrin according to WHO criteria. Kdr mutations were investigated using PCR. Results of morphological identification showed an abundance (100%) of the Anopheles gambiae complex. However, molecular identification showed varying percentages of An. gambiae s.s (15% and 35%), An. coluzzii (80% and 45%), and An. arabiensis (5% and 20%) each for agricultural and industrial sites, respectively. The result also revealed relatively higher KT₅₀ and KT₅₀ in the agricultural site and was relatively higher with permethrin based on the KT₅₀. Higher insecticide resistance of Anopheles mosquitoes observed in the agricultural site suggests that the practice may affect resistance development. The frequency of negative (homozygous) L1014F kdr mutation genotype was 70% in the resistant (alive) mosquito population and 50% in the susceptible (dead) mosquito population. The frequency of kdr mutation for agricultural and industrial sites was 35% and 15%, respectively. This finding suggests that the kdr gene determinant may not be the only mechanism involved in the resistance of the Anopheline mosquito to pyrethroid.