Dietary studies of Aquatic insects from two Victorian rivers

Abstract

A preliminary assessment of the feeding habits of 127 taxa of pre-imaginal Coleoptera, Diptera, Ephemeroptera, Plecoptera and Trichoptera from the La Trobe and Tanjil Rivers was made from analyses of digestive tract contents and observations of captive specimens. Ultrafine (<50 µn) detritus was the dominant material in gut contents of all five orders, and fine (< 1 mm, > 50 µlm) detritus (mostly leaf and wood fragments), benthic algae (especially diatoms) and remains of invertebrate prey were also important. Bacteria, fungi and planktonic algae were present in minor quantities. Many species were shown to be capable of shredding dead leaves and wood. Dietary diversity was particularly high in the families Elmidae, Chironomidae, Leptophlebiidae, Gripopterygidae and Leptoceridae.