Amblyospora

Abstract: Amblyospora species and other aquatic Microsporidia were isolated from mosquitoes, black flies, and copepods and the small subunit ribosomal RNA gene was sequenced. Comparative phylogenetic analysis showed a correspondence between the mosquito host genera and their Amblyspora parasite species. There is a clade of Amblyospora species that infect the Culex host group and a clade of Amblyospora that infect the Aedes/Ochlerotatus group of mosquitoes. Parathelohania species, which infect Anopheles mosquitoes, may be the sister group to the Amblyospora in the same way that the Anopheles mosquitoes are thought to be the sister group to the Culex and Aedes mosquitoes. In addition, by sequence analysis of small subunit rDNA from spores, we identified the alternate copepod host for four species of Amblyospora. Amblyospora species are specific for their primary (mosquito) host and each of these mosquito species serves as host for only one Amblyospora species. On the other hand, a single species of copepod can serve as an intermediate host to several Amblyospora species and some Amblyospora species may be found in more than one copepod host. Intrapredatorus barri, a species within a monotypic genus with Amblyospora-like characteristics, falls well within the Amblyospora clade. The genera Edhazardia and Culicospora, which do not have functional meiospores and do not require an intermediate host, but which do have a lanceolate spore type which is ultrastructurally very similar to the Amblyospora spore type found in the copepod, cluster among the Amblyospora species. In the future, the genus Amblyospora may be redefined to include species without obligate intermediate hosts. Hazardia, Berwaldia, Larssonia, Trichotuzetia, and Gurleya are members of a sister group to the Amblyospora clades infecting mosquitoes, and may be representatives of a large group of aquatic parasites.

Abstract: Meiospores of a microsporidian parasite Amblyospora sp. (Protozoa: Microspora) from larval Aedes cantator mosquitoes were directly infectious to an alternate copepod host, Acanthocyclops vernalis (Arthropoda: Crustacea). Infections ranged from 6.7% to 60.0% in laboratory tests when meiospores and copepods were maintained together for 10-30 days in filtered water from the breeding site or in a balanced salt solution. Pathogen development takes place within host adipose tissue and is fatal to the copepod. The entire developmental sequence of this microsporidian in the copepod is unikaryotic and there is no ultrastructural evidence of a sexual cycle or a restoration of the diploid condition in the alternate host. Single uninucleated spores similar to those previously described for the genus Pyrotheca are formed. Results demonstrate that haploid meiospores of Amblyospora from mosquitoes have the function of transmitting the pathogen to another host and that members of this genus are polymorphic and have at least three distinct developmental cycles, each producing a different spore.