Mechanisms of Infection ; Microsporidian Life Cycles ; Pathology ; Host Population ; Susceptibility to Microsporidiosis ; Immune Response ; Behavioral Response ; Pathogen Population ; Virulence of Microsporidian Pathogens ; Host Specificity ; Physiological vs. Ecological Host Specificity ; Host Range ; Alternate Hosts ; Microsporidia Crossing the Invertebrate–Vertebrate Barrier ; Persistence in the Environment ; Transmission ; Horizontal Transmission ; Transmission from Living Hosts ; Transmission after Host Death ; Transmission by Parasitoid Vectors ; Effects of Host Development and Host–Microsporidia Interactions on Transmission ; Vertical Transmission ; Epizootiology ; Microsporidian Prevalence in Invertebrate Populations and Impact on Host Populations ; Microsporidia in Cultured Insects ; Microsporidia as Potential Biological Control Agents