Comparison of the dietary habits of six species of Dinotoperla (Plecoptera : Gripopterygidae) in Victoria

Abstract

The dietary habits of six species of Dinotoperla were determined by field and laboratory observations, nymphal gut analysis, and examination of mouthparts. All the species (D. bassae, D. brevipennis, D. christinae, D. eucumbene, D. fontana and D. thwaitesi) could be classified as herbivore-detritivores, and in each there was a shift from a diet primarily of fine particulate matter to a more polyphagous habit with increasing nymphal size. The diets of the six species were similar, consisting of diatoms, filamentous green algae (except in D. eucumbene), fupgal hyphae, fine particulate matter and vascular plant tissue. However, differences were observed in the nutritional quality of their diets in terms of protein and calorific content. The two smallest species studied, D. brevipennis and D. eucumbene, consumed mostly fine particulate matter-the least nutritionally valuable of available food items (apart from wood, which was not eaten by Dinotoperla nymphs). D. eucumbene was also the slowest growing of the six species. The fastest-growing species, D. bassae, was also the largest, and the nymphs of this species consumed the highest-quality diet, eating large amounts of filamentous green algae and diatoms.