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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. [ABSTRACT FROM AUTHOR]

Background: Malaria is a major public health problem and life threatening parasitic vector-borne disease. For the first time, we established and report the molecular mechanism responsible for Anopheles gambiaes.l. resistance to pyrethroids and DDT from Yamaltu Deba, Southern Guinea Savanna, Northern-Nigeria. Methods: The susceptibility profile of An. gambiaes.l. to four insecticides (DDT 4%, bendiocarb 0.1%, malathion 5% and deltamethrin 0.05%) using 2–3 days old females from larvae collected from study area between August and November, 2018 was first established. Genomic DNA was then extracted from 318 mosquitoes using Livak DNA extraction protocol for specie identification and kdr genotyping. The mosquitoes were identified to species level and then 96 genotyped for L1014F and L1014S kdr target site mutations. Results: The mosquitoes were all resistant to DDT, bendiocarb and deltamethrin but fully susceptible to malathion. An. coluzzii was found to be the dominant sibling species (97.8%) followed by An. arabiensis(1.9%) and An. gambiae s.s(0.3%). The frequency of the L1014F kdr mutation was relatively higher (83.3%) than the L1014S (39%) in the three species studied. The L1014F showed a genotypic frequency of 75% resistance (RR), 17% heterozygous (RS) and 8% susceptible (SS) with an allelic frequency of 87% RR and 13% SSwhile the L1014S showed a genotypic frequency of RR (16%), RS (38%) and SS (46%) with an allelic frequency of 40% RR and 60% SS, respectively. Conclusion: This study reveals that both kdr mutations present simultaneously in Northern-Nigeria, however contribution of L1014F which is common in West Africa was more than twice of L1014S mutation found in East Africa. [ABSTRACT FROM AUTHOR]