Predator-Prey Relationships Among Aquatic Insects

Abstract

It is not surprising that the majority of studies concerning aquatic insect predator­ prey relationships involve the aquatic stages of mosquitoes as the prey (26, 40), and in some instances as the predator (14, 15, 68). Most mosquito larvae are easy to rear and maintain, and make excellent prey for a wide variety of aquatic organisms. In addition, the biting nuisance and disease vector significance of many species of adult mosquitoes has encouraged considerable attention being given to their natural enemies. Other than mosquito larvae, simuliid larvae ·and chironomid larvae are the most frequently studied invertebrate prey in the freshwater habitat. Neither of these groups, however, are as convenient to rear or as easy to observe for predation as are mosquito larvae. Most chironomid larvae dwell in tubes or in mud, while most blackfly larvae occur attached to rocks in fast-flowing streams (39). Predator-prey relationship studies involving other aquatic insects are few (18, 75). Laboratory studies of aquatic insect predation are fairly common, but field evalu­ ations have been relatively rare. These have been restricted mostly to rock pools (35, 60) and other small or container-like bodies of water (38). This is not surprising when one considers the difficulties involved in viewing insects through a reflective surface that is often moving and distorted, or obscured with plants, debris, or scum. Moreover, the water itself is often too murky from either algae or sediment for direct observation, and where it is clear many predators and prey are too small and too well camouflaged to be visible. Stationary underwater observation structures (3) permit a truer understanding of prey selection and predator behavior than can be obtained in aquaria, but quantitative assessment of predator effects are more difficult to obtain. Mosquito and chironomid midge larvae for instance, are quick to appear in newly filled depressions and temporary ponds. These prey are followed almost simultaneously by a large array of predators that feed also upon one another, and upon a constant rain of terrestrial insects that fall upon the water surface (19, 73).