Laboratory An. gambiae s.l. mosquito colonies show sustained high transmission of Microsporidia sp. MB and a small decrease in egg viability

Introduction: control strategy would involve dissemination through live mosquito releases, or release of spores infective to mosquito larvae. To implement either strategy, establishment of stable mosquito colonies carrying MB at a high frequency is likely to be essential. Methods: host was examined using a novel duplex qPCR assay. We also examined the impact of MB on egg production through individualization for egg laying and counting of eggs. Finally, we examined laid eggs for presence of MB spores. Results: hybrid colony were established with high prevalence and density of MB and were maintained for more than two years with minimal intervention. MB prevalence and density was highest in eggs and adult females and lowest in L4 larvae; in adults density was highest in the gonads. Additionally, MB density increased in ovary samples following blood feeding which was likely due to the activation of sporogony. Discussion: colonies and understanding the impact of spores on egg production are significant steps forward in developing MB as a malaria control tool.