Distribution of Members of the Anopheles Gamibiae s.l. In Oyo State, South West Nigeria

Abstract

Background: Members of the Anopheles gambiae s.l. remain the most efficient vectors of malaria parasite in Africa. However, for timely and effective vector control activities, the distribution of these important vectors in local communities is crucial. We therefore determine the distribution of the members of Anopheles gambiae s.l. in Oyo State, Nigeria Methods: Larval stages of Anopheles mosquitoes were collected from identified mosquito breeding sites in six localities (Oluyole, Eruwa, Oyo, Ojoo, Bodija, and Ogbomoso) in Oyo State and reared to adults. Three to five days old adult emergence were identified morphologically using standard methods. A total of 100 mosquitoes were selected from each of localities for molecular analysis. DNA were extracted and Polymerase Chain Reaction (PCR-ID) followed by restriction endonucleases digestion was used for molecular identification. Results: A total of 58 larval breeding sites were sampled out of which 12 (20.7%) had Anophelines only, 21 (36.2%) contained Culicines only and the remaining 25 (43.1%) had both Anophelines and Culicines. The mosquitoes were mostly found in footprints, followed by tire tracks, pools, puddle and ponds. The habitat type distribution for Anopheline and Culicines were not different (χ2=5.25, DF=5, P>0.01). A total of 1,725 Anophelines emerged from the collection out of which, 823 were females. All the female samples were morphologically identified as members of the Anopheles gambiae s.l.. A total of 600 (72.9%) of the female Anopheline population was subjected to PCR. PCR-ID showed that the mosquito populations contained higher numbers of Anopheles arabiensis (58%) than Anopheles gambiae s.s. (42%). Enzyme digest indicate that samples from Oluyole, Iwo road and Bodija were man-ly the M form (now called An. coluzzii), while both M (An. colizzii) and S (An. gambiae) form occur in sympatry in Oyo town and Eruwa. Conclusion: This study presents information on the distribution of Anopheles arabiensis, Anopheles coluzzii and Anopheles gambiae in Oyo State. This has implication on the vector control activities in the State as members of these Anopheles mosquitoes exhibit varying feeding behaviours, transmission pattern and resistance profiles. Such information is useful in planning vector control activities for the State