Watermite parasitism of corixidae: infection parameters, larval mite growth, competitive interaction and host response

Abstract

Parasitism of four corixid species in Lough Corrib, western Ireland, by larval water-mites of the genera Hydrachna and Eylais was investigated. Differences in abundances of mite species were noted in respect of host species and different sampling localities. Infection parameters were not affected by host size, although host sex seemed to influence Hydrachna parasitism. Partial temporal separation of mites was observed in respect of larval attachment to hosts and emergence of nymphs. The largest nymphs were generally recorded from the largest hosts and from single infections. Intraspecific and interspecific competition was evident among parasites for host nutritive resources and growing space, especially on smaller hosts. The feeding intensity of parasitised Cymatia bonsdorfi was significantly greater than that of unparasitised bugs. Increased feeding by parasitised C. bonsdorfi may have been an attempt to compensate for the effects of nutritional drain by H. conjecta.