Molecular Evidence of high prevalence of Wolbachia Species in Wild-Caught Aedes albopictus and Aedes aegypti mosquitoes on Bioko Island, Equatorial Guinea

Background: Distribution of Aedes albopictus and Aedes aegypti are currently unknown on Bioko Island Equatorial Guinea. Methods: Aedes spp. were collected between February 2020 and August 2021 on Bioko Island as a by-product of malaria vector entomological surveillance. The mosquitoes were transferred to Switzerland . Utilizing qPCR (quantitative polymerase chain reaction) on extracted nucleic acids, the mosquitoes were distinguished between A. albopictus and A. aegypti . Subsequently, the host species of their last blood meal was identified. Metagenomic analyses of potential pathogens were performed using Oxford Nanopore sequencing. A qPCR assay to detect Wolbachia was developed and used to screen Aedes spp. Results: A. albopictus represents the dominant Aedes species on Bioko Island. Aedes spp. mosquitoes predominately fed on humans, few A. albopictus positive pools additionally contained blood meals from dog or chicken. Eight out of nine tested Aedes spp. pools contained DNA sequences that matched to Wolbachia spp. assessed by metagenomics. The remaining 72 pools were tested by qPCR for presence of Wolbachia spp. DNA. In total, 87% of all samples tested were positive for Wolbachia spp. A. albopictus seemed to be significantly more affected by Wolbachia spp. than A. aegypti . Conclusions: A. albopictus has become the dominant Aedes species on Bioko Island and can be found in all four districts. Wolbachia spp. endosymbionts seem to be more prevalent in A. albopictus compared to A. aegypti . The impact of Wolbachia spp. presence on potential transmission of Flaviviruses in these different local mosquito populations warrants further investigation.