Blastocladian parasites of invertebrates

Abstract

Some species of zoosporic fungi in the Phylum Blastocladiomycota are obligate parasites of invertebrate animals. Various stages in the life history of the host can be infected, including eggs, larvae and adults. Some parasites, such as some species of Coelomomyces, alternate between two hosts; while others, such as some species of Catenaria, require only one host for reproduction. Infection generally begins after zoospores attach to the outer surface of the host body or to the gut wall. Host specificity and parasite virulence vary broadly among species. Some parasites such as Coelomomyces and Catenaria can naturally regulate dipteran insect or nematode populations. New roles for Blastocladian parasites in food web dynamics have recently been discovered. For example, the parasite Polycaryum can reduce the quantity and quality of Daphnia hosts as a food resource for planktivorous fish. We propose that zoosporic fungal parasites contribute significantly to the biodiversity and the complexity of the food webs in freshwater and soil ecosystems. Further research is needed to highlight the importance of zoosporic fungal parasites in aquatic ecosystems.