Susceptibility of female Anopheles mosquito to pyrethroid (Alphacympermethrin 0.5%) and Carbamate (Propoxur 0.1%) in Keffi Local Government Area of Nasarawa State, north-central Nigeria
The detection of insecticides resistance status in a natural population of Anopheles vectors is a vital tool for malaria control intervention strategy against Anopheles gambiae sensu lato, which is the main malaria vector in Nigeria. This study was conducted to determine the susceptibility status of the female Anopheles mosquitoes to Propoxor (0.1%) (Carbamate) and Alphacympermetrin (0.5%) (Pyrethroid) insecticides in Keffi LGA of Nasarawa State, Nigeria, between March and June, 2015. The larvae were collected from natural water bodies and other potential breeding sites from five different sites in Keffi LGA namely; Angwan Lambu, High Court, Angwan Kwara, Antau Bridge and Pyanku they were raised in the insectary located at Nasarawa State University, Keffi. WHO bioassay were performed using 2-3 days old, glucose-fed but non-blood fed female Anopheles mosquitoes. The knock down effect of Propoxur in the five locations in Keffi LGA was more pronounced with mortalities ranging from 84%-98% (p<0.05) and Alphacympermethrin recording a higher knock down in Angwan Kwara with 95% and with mortalities ranging from 78%-85% (p<0.05). The result of the bioassay showed reduced efficacy of Alphacypermethrin with resistance in some locations. However, Propoxur recorded higher mortality (100%, 100%, 95%, 100%, and 100%) respectively in the five sampled areas. Using chi-square statistical analysis; there was a significant difference between knockdown times with respect to Propoxur (p<0.05). Insecticide based intervention strategy remain the principal vector control measure in malaria endemic countries prompting the recommendation of Propoxur in the future vector control programs because high mortalities of the vectors were noticed in the assay run by the Carbamate class of insectide (Propoxur).
Keywords: Anopheles mosquitoes, Pyrethroid and Carbamate insecticides, resistance, Nasarawa State