Microsporidian Entomopathogens

Microsporidia, pathogenic protists related to the Fungi, are considered to be primary pathogens of many aquatic and terrestrial insect species and have important roles in insect population dynamics, managed insect disease, and biological control of insect pests. Hosts are infected when spores are ingested and/or by transmission via the eggs. When ingested, spores germinate in a unique fashion: a polar tube that is coiled within the spore rapidly everts and punctures the host midgut cells, injecting the spore contents into the cell cytoplasm. Mitochondria and Golgi bodies are lacking in these obligate intracellular pathogens, and energy is evidently extracted from host cells via direct uptake of ATP. Effects on the host are typically chronic; therefore, the use of Microsporidia, pathogenic protists related to the Fungi, are considered to be primary pathogens of many aquatic and terrestrial insect species and have important roles in insect population dynamics, managed insect disease, and biological control of insect pests. Hosts are infected when spores are ingested and/or by transmission via the eggs. When ingested, spores germinate in a unique fashion: a polar tube that is coiled within the spore rapidly everts and punctures the host midgut cells, injecting the spore contents into the cell cytoplasm. Mitochondria and Golgi bodies are lacking in these obligate intracellular pathogens, and energy is evidently extracted from host cells via direct uptake of ATP. Effects on the host are typically chronic; therefore, the use of microsporidia in biological control programs focuses on inoculative introductions, augmentative release, and conservation biology. This chapter reviews the biology, ecology, pathology, and classification of microsporidia with examples of several long-term research efforts to manipulate these pathogens for the suppression of insect pests.