Microhabitat selection by the fishfly larva, Parachauliodes japonicus, in relation to its mode of respiration

Abstract

SUMMARY. 1. Larvae of Parachauliodes japonicus (Megaloptera: Corydalidae) were tracked in streams using miniature radio‐transmitters.2. Larvae usually stayed under stones in shallow water for several days, but occasionally moved about on the stream bed at night.3. Larvae possess a pair of respiratory tubes on abdominal segment VIII, which can be used as a snorkel to obtain oxygen from the atmosphere. Because respiratory rates decreased as dissolved oxygen decreased, larvae turned to air‐breathing under lowered oxygen conditions. When in shallow water, they can alter respiratory mode from aquatic respiration to air breathing instantly by raising their caudal respiratory tubes to the surface of the water.4. Microhabitat selection and respiratory behaviour are compared with those obtained previously for Protohermes grandis larvae, which belong to the same family and often inhabit the same stream as P. japonicus, but which have gill tufts on abdominal segments I‐VII instead of respiratory tubes. The respiratory constraint on microhabitat preference by aquatic insects is discussed.