Neglected Predators: Water Mites (Acari:Parasitengona:Hydrachnellae) in Freshwater Communities

Abstract

Despite the abundance and ubiquity of water mites, their importance as predators in freshwater communities is seldom investigated. This neglect is likely due both to the perceived difficulty in identifying aquatic mites, and to the lack of easily available information on the feeding habits of these animals. We review the literature on water mite feeding, translating (from German) the only previous compendium of predator-prey relationships, and adding recent reports and unpublished observations. Diets of 38 genera in 21 families are described. Reports of herbivory, detritivory, and saprophagy are dismissed and several trends are noted. Mites that eat insect eggs as adults tend to parasitize the same insect taxa during their parasitic larval stage. Lentic mites can be grouped into egg-specialists, those that concentrate on crustaceans, those that concentrate on insect larvae, and generalists. Lotic mites appear to feed primarily on chironomid larvae. A discussion of the predatory behaviour of water mites follows the compendium.