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Abdullahi, M. A.

Publications and source records attributed to Abdullahi, M. A..

2 recordsLinked to original sources
bioRxiv2026

Increasing Pyrethroids and DDT Resistance and kdr Mutation in Anopheles gambiae s.l. from Sokoto, North-West Nigeria

BackgroundAnopheles gambiae sensu lato (s.l.) is the primary vector of malaria in sub-Saharan Africa. Although insecticide-based vector control has been central to prevention, the widespread emergence of insecticide resistance poses a serious biological threat to control efforts. Effective resistance monitoring is essential for sustaining vector control but remains highly limited in malaria-endemic hotspots. Here, we assessed pyrethroid and DDT resistance intensity and the frequency of the L1014F knockdown resistance (kdr) mutation in Anopheles gambiae s.l. populations from Sokoto, north-western Nigeria. MethodologyResistance status and intensity to five insecticides were determined in adult Anopheles reared from larvae collected in 2021 and 2022 using the World Health Organization (WHO) tube test and Centers for Disease Control and Prevention (CDC) bottle bioassay, respectively. A subset of resistant mosquitoes was analyzed using PCR-based diagnostic assays to identify species within the Anopheles gambiae complex and to genotype for the West African kdr mutation (L1014F). ResultsHigh knockdown times (KDT) were observed, with KDT50 ranging from 38 to 91 minutes and KDT95 from 104 to 678 minutes, indicating increased resistance levels across all insecticides. In 2021, resistance was detected to DDT, lambda-cyhalothrin, and permethrin, while susceptibility to alpha-cypermethrin (98%) and suspected resistance to deltamethrin (91%) were recorded. In 2022, a general increase in resistance to all insecticides was observed, with mortality rates ranging from 41% to 81%. High resistance intensity was observed against DDT, while permethrin and alpha-cypermethrin exhibited low resistance intensity in both years, failing to reach 10x the diagnostic dose. Deltamethrin and lambda-cyhalothrin showed low to moderate resistance intensity. The 1014F kdr mutant genotype was widely distributed (68.1%) across species and years. Allele frequencies were higher in An. gambiae s.s. (0.83) than in An. arabiensis (0.71), with significant deviations from Hardy-Weinberg equilibrium (p < 0.05), except for An. gambiae s.s. in 2021 (p = 0.7). ConclusionThese findings reveal a concerning increase in key insecticide resistance among Anopheles populations in Sokoto, underpinned by strong genetic mechanisms. This underscores the urgent need for integrated vector management strategies to sustain effective vector control efforts in the region.

zoology↗
bioRxiv2026

Mosquito Specie Composition and Pyrethroid Resistance Status in Daura, Maiadua and Sandamu LGAs, Katsina State

BackgroundMalaria and other mosquito-borne diseases remain major public health in Nigeria. Insecticide-based interventions are vital for disease control but their effectiveness is threatened by the limited knowledge of local mosquito species and their resistance to insecticides. AimThe aim of this research is to determine the specie composition and pyrethroid resistance status of mosquitoes in Daura, Maiadua and Sandamu local governments, Katsina state. Materials and MethodMosquito larvae were collected from different locations in the study area between July to October and reared to adults in general Biology lab, federal polytechnic Daura. The adult mosquitoes were identified and subjected for bioassay. Five different WHO insecticide-impregnated papers namely Alphacypermetrin, Deltametrin, Lambdacyhalothrin and Permethrin were used for this study. The impregnated papers were tested against the emerged adult mosquitoes using WHO standard operating procedure. Culex and Aedes were morphologically identified to specie level while Anopheles were molecularly identified. The kdr mutation was also assessed in the Anopheles mosquitoes. ResultsAll the three genera; Anopheles, Culex and Aedes were present in the study area with Anopheles being the dominant. Culex quinquifasciatus and Aedes aegypti were the dominant species of Culex and Aedes respectively, while Anopheles gambiae s.l. was the dominant Anopheles species. Bioassays revealed widespread resistance to all the tested insecticides across all genera and locations, with particularly high resistance to deltamethrin, (mortality rates 17-48%). molecular analysis showed a high frequency of the 1014 mutation in the Anopheles mosquito. Conclusion and RecommendationsAnopheles gambiae s. l., Culex quinquifasciatus and Aedes aegypti are the dominant mosquito species in the study area. Deltametrin was less effective than the other classes of pyrethroids. These findings are important for guiding malaria control programs in Nigeria particularly in selecting effective insecticides for vector management.

zoology↗