Microsporidia have long been proposed as biological agents for controlling disease vectors and the parasites they transmit. However, their study in vector biology has been constrained due to challenges in manipulating microsporidia within hosts. In this study, we investigated the effect of Dexrazoxane, a candidate drug against microsporidiosis, on the establishment and development ofVavraia culicisinfection in its natural host, the mosquitoAnopheles gambiae, the main malaria vector. Our findings show that Dexrazoxane significantly reduces spore load, particularly in mosquitoes reared individually, without affecting the overall infection success of the parasite. This result aligns with studies inCaenorhabditis elegans, where Dexrazoxane inhibited new spore production without hindering initial spore integration into the host gut cells. Dexrazoxane's DNA topoisomerase II inhibitor mechanism likely explains its impact on mosquito development, as larvae exposed to the drug failed to emerge as adults. These findings highlight Dexrazoxane's potential as a viable tool for controlling microsporidia in adult mosquitoes and hope to enhance the study of mosquito-microsporidia interactions. Further research is required to explore its broader application in vector-borne disease control, including malaria.