Microsporidian infection of Culex peus

Larvae of Culex peus were collected from a small, grassy, muddy pond. Two of these larvae showed external symptoms related to microsporidian infection, such as swollen appearance and porcelain-like color. This spore is similar to Amblyospora californica from Cx. tarsalis in morphology and in development, and like Am. californica, is not infective to uninfected larvae. This suggested that it was a species belonging to the genus Amblyospora. It is, however, apparently a different species since its size is significantly smaller than that of Am. californica, although these two species sometimes occur in the same breeding sites. Larvae were never infected when they were fed with spores from lethally infected larvae or from water of the breeding site. This indicates that the microsporidian could not complete its developmental cycle in the mosquito host. Whether or not they need an alternate host, such as copepod which have been found to serve as an intermediate hosts for several other species of Amblyospora, remains to be worked out.