Alteration of Host Stage Distribution by Parasitic Water Mites of the Species Hydrachna virella (Acari: Hydrachnidae)

Abstract

The effect of a parasitic water mite, Hydrachna virella, on the stage distribution (the proportion of the host population represented by a stage) of its aquatic insect host, Buenoa scimitra, was studied using a stage-based matrix model. Despite killing members of several stages, the mite increased the stage-distribution values of those stages. This effect seems to result from a lag in the rate of development of parasitized hosts; parasitized hosts remain in a stage longer. Consequently, a stage with parasitized individuals would represent a larger proportion of the host population than would the same stage with only unparasitized individuals. Parasites that delay host development can bias field estimates of prevalence or proportion of a host population (or stage) parasitized.