Aquatic Insects – Ecology, Feeding, and Life History

Abstract

Although only ∼4% of the 1 million described species of insects are considered aquatic, their occurrence in essentially all freshwater habitats, and their position as the dominant class of macroinvertebrates in many of these, provides evidence of a broad evolutionary diversification. The structure of aquatic insect communities is closely tied to physical habitat attributes and further influenced by biological factors such as dispersal, competition, and predation. Essentially, no aquatic insects are completely aquatic. With very few exceptions, terrestrial habitats are required for one or more life-cycle stages. The duration of their life cycles has a wide range, even among closely related taxa. The life cycle of midges of the Chironomidae (Diptera), as an example, may be as short as 1 week or as long as several years depending upon species and habitat. As primary consumers, aquatic insects feed on biofilms, periphyton, detritus, and less commonly, the tissues of living macrophytes. As secondary consumers, they are primarily predators of other invertebrates. Because of their generalized diets, aquatic insects are often classified on the basis of feeding mechanisms to better understand their function within their communities. The major functional-feeding groups, which emphasize feeding mechanisms rather than food type, include shredders, scrapers, collector-gatherers, collector-filterers, engulfing-predators, and piercers.