Molecular Characterization of Wolbachia Endosymbiont Strains in Anopheles Mosquitoes from Transmission-Intense Malaria Sites in Ogun State

Wolbachia, an intracellular endosymbiotic bacterium naturally present in a large fraction of insect species, has gained global attention as a potential malaria transmission-blocking tool, given its demonstrated ability to inhibit Plasmodium falciparum development in Anopheles mosquitoes. Characterizing indigenous Wolbachia strains in Nigerian Anopheles populations is a prerequisite for local vector control strategy development. This study molecularly characterized Wolbachia endosymbiont strains in Anopheles mosquitoes collected from malaria-intense transmission sites in Ogun State, Southwest Nigeria. Adult Anopheles mosquitoes were collected by pyrethrum spray catch and CDC light traps across five collection sites. DNA was extracted from individual mosquitoes, and Wolbachia presence was screened by PCR targeting the 16S rRNA and wsp gene. Wolbachia supergroup classification was determined by multilocus sequence typing (MLST). Wolbachia was detected in 14.2% of all Anopheles specimens tested, with significantly higher prevalence in An. coluzzii (19.3%) compared to An. gambiae s.s. (9.7%). Sequence analysis confirmed all detected strains belonged to supergroup B, distinct from the A-group strains used in Aedes-based biocontrol programs. MLST profiling revealed two distinct sequence types specific to Nigerian Anopheles populations. These molecular findings define the natural Wolbachia endosymbiont landscape in Ogun State Anopheles populations and provide strain-level information critical for localized Wolbachia-based vector control strategy development. Keywords: Wolbachia, Anopheles, malaria vector control, wsp gene, Ogun State.