Current Status of Insecticide Susceptibility in the Principal Malaria Vector, Anopheles gambiae in Three Northern States of Nigeria

Background: Malaria is a major public health problem in Nigeria with 97% of its population with high morbidity and mortality. Mosquitoes play an important role in the transmission of malaria parasites. This study was conducted to eval­uate the current resistance status of Anopheles gambiae to insecticides. Methods: Larvae of An. gambiae was collected from three zones; A, B and C differentiated on the basis of variation in agricultural ecosystems between August and November, 2018 in the northeast and northwestern parts of Nigeria. They were carefully reared to adult stage and insecticidal susceptibility tests were conducted. Results: The mosquitoes tested showed high levels of resistance to all the insecticides used with the exception of mala­thion. Study zone A, recorded 74% mortality after 24h to deltamethrin compared to 81% from zone B and 82% from zone C, respectively. Mosquitoes from zone B exposed to DDT had the highest level of resistance at 37% compared to 40% and 53% from zones A and C, respec­tively. Resistant to bendiocarb was also observed, with zone A having the lowest mortality of 44% com­pared to 48% from zone C and 55% from Zone B, respectively. According to the results of knockdown tests, mosquitoes from Zone A exposed to deltamethrin recorded the lowest knockdown across the study locations while zone B recorded the lowest knockdown for DDT. Conclusion: The results of the study provide an insight into the current status of An. gambiae to four major insecticides in northern Nigeria as guideline for mosquitocontrol.