Breeding water parameters are important determinants of Microsporidia MB prevalence in the aquatic stages of Anopheles mosquitoes

The fungus, Microsporidia MB disrupts Plasmodium development in Anopheles mosquitoes. It has been associated with An. gambiae and An. coluzzii (Ghana), and An. arabiensis (Kenya) from rice fields. As a tool for vector/disease control, its ecological distribution and factors that determine their occurrence must be defined. We investigated the prevalence of Microsporidia MB in Anopheles mosquitoes across selected sites in Ghana, and the breeding water physicochemical parameters that are associated with the occurrence of the fungus by fitting regression models. DNA was extracted from the abdomens of 4255 adult Anopheles mosquitoes that emerged from larvae and pupae collected from selected sites in northern and southern Ghana between August and October of 2021 and 2022. Detection of Microsporidia MB was achieved using qPCR, while species were molecularly identified using SINE, RFLP methods, and the ANOSPP algorithm. Overall Microsporidia MB prevalence was 2.2%. Male mosquitoes exhibited higher prevalence of infections and had increased predicted probability of infection 85% higher than females. Sawla, in Ghana's Savannah zone had the highest MB prevalence (56.52%) despite lacking rice fields. Biochemical oxygen demand in mosquito breeding water was estimated to be positively associated with and, significantly predicts MB prevalence in mosquitoes with an accuracy of 94%. According to our data, all Anopheles species were at equal probability of MB infection. These results provide preliminary information on micro-ecological factors that could support the sustainability of MB infection in mosquitoes during their aquatic life stages. It will be important, therefore, to explore the impact of strategies for larval source management on these factors to ensure that the symbiont's persistence during the host's aquatic stages may not be adversely affected should it be used as an integrated approach for mosquito/disease control.