Lake flies in Lake Victoria: their biomass and potential for use in animal feeds
1992
Okedi, J. (Makerere Univ., Kampala (Uganda). Dept. of Zoology)
Insects exhibiting swarming habits in Lake Victoria include mainly the Chironomidae, the Chaoboridae and Povilla adusta (Ephemeroptera). Their early life cycles are spent in the lake as benthos and standard bathymetric procedures were undertaken to estimate the standing crop biomass of the larvae in Murchison Bay. Povilla was principally a boring invertebrate preferring dried logs (113g Povilla nymphs per kg of host plant material). Cyperus papyrus carried 5 g C. denudatus 2.5 g and Phragmites mauritanus 1.0 g to Povilla per kg of host plant material. Povilla also occured in the benthos at 40 g/m. The Chironomidae and Chaoboridae had a mean standing crop biomass of 80 g/m25 and 3 g/m respectively. Their total biomass for the bay was estimated at 16060 metric tonnes for the Chiromomidae, 7920 m.t. for Povilla and 660 m.t. for the Chaoborids. Adult swarming habits of the lakefly were closely correlated with lunar phases and the adults were easily trapped at night using kerosene lamps. Biochemical tests of the nutrient value of lakefly showed high levels of protein content (62), minerals (18), a low fat content (3.9) and low moisture content (9). This makes the lakefly ideal as an additive in animal feeds and growth experiments with poultry and aquaculture fish are currently going on to test the suitability of lakefly as an ingredient in animal feeds
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