Organic matter processing by chironomid larvae (Diptera : Chironomidae)

In laboratory experiments, we used fluorescent dye markers to investigate p rocessing of organic matter by larvae of Psectrocladius limbatellus (Holm.) (Diptera: Chironomidae). 59% of the organic matter used was incorporated i nto tubes, 39% was present in faecal pellets (both after 24 h), and 2% was found in the larval gut at the end of experiments. Ingested matter passed t hrough the gut rapidly, resulting in the gut being emptied more than 20 tim es each day. Further 24-h experiments using dye-marked faecal pellets showe d that 6% of pellets produced were reingested and 12% were incorporated int o tubes. There was no preference for conditioned faecal pellets as food ove r those that had recently been egested and tubes also provided a food reser ve on which larvae feed. Chironomid larvae recycle organic matter resulting in its mineralization and their 'engineering' has a dramatic effect on the substratum.