Microsporidia in Insects

This chapter highlights the biological and life cycle features of entomogenous microsporidia and provides some basic information on their taxonomic distribution. The development of all insect-parasitic microsporidia is restricted to the cytoplasm of the host cell. The development of all insect-parasitic microsporidia is restricted to the cytoplasm of the host cell. Specialized relationships between microsporidia and the host at the cellular level have been termed xenomas. Weiser distinguished two main types of xenomas in insects, syncytial and neoplastic. The chapter presents the major and minor pathways of transmission for insect microsporidia. Alternatively, the criteria used to establish the genera of microsporidia from aquatic insects may not truly reflect phylogenetic diversity but adaptations to specific habitats and host systems. A section lists a few genera for which insects are not the type hosts. This is because many species have been reported to occur in insects (such as Thelohania, Pleistophora) or because there are possible links to insect microsporidia (such as Trichotuzetia). Finally, the chapter provides diagnostic information which is primarily restricted to the features of sporulation and the spore, with the addition of distinguishing life cycle characteristics when available. The type host and species are given followed by comments on distribution and other matters deemed of importance.