Lake flies in Lake Victoria: Their biomass and potential for use in animal feeds

Abstract

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 (113 g Povilla nymphs per kg of host plant material). Cyperuspapyrus carried 5 g C. denudatus 2.5 g and Phragmites mauritanus 1.0 g of Povilla per kg of host plant material. Povilla also occurred in the benthos at 40 g/m 2 . The Chironomidae and Chaoboridae had a mean standing crop biomass of 80 g/m 2 and 3 g/m 2 respectively. Their total biomass for the bay was estimated at 16060 metric tonnes for the Chironomidae, 7920 m. t. for Povilla and 660 m. t. for the Chaoborids. Adult swarming habits of the lakefiy were closely correlated with lunar phases and the adu Its were easily trapped at night using kerosene lamps. Biochemical tests of the nutrient value of lakefiy showed high levels of protein content (62%), minerals (18%), a low fat content (3.9%) and low moisture content (9%). This makes the lakefiy ideal as an additive in animal feeds and growth experiments with poultry and aquaculture fish are currently going on to test the suitability of lakefiy as an ingredient in animal feeds. Resume-Les insectesessaiment dans le Lac Victoria comprennent surtout les Chironomidae, les Chaoboridae et Povilla adusta (Ephemeroptera). La premiere partie de leur cycle est passee dans le Lac comme benthos et des proced ures standard de Bathymetrie e talent utilisees pour estimer la biomass des larves dans MurchisonBay. Povilla etait principalement un invertebre qui p re fere des pieces de bois sec he (113 gr Povilla nymphes par kilo de materiel vegetal). Cyperus papyrus avait 5 gr., C. dennatus 2.5 gr., et Phragmites mauritanus 1.0 gr. de Povilla par kilo de materiel vegetal. Povilla etait aussi present dans le benthos avec une densite de 40 gr. par metre carre. Les Chironomidae avait une densite moyenne de 80 gr. par metre carre, les Chaoboridae 3 gr. par metre carree. La biomasse totale de Murchison Bay est estimee a 16060 tonnes pour les Chironomidae, 7920 tonnes pour Povilla et 660 tonnes pour les Chironomidae, 7920 tonnes pour Povilla et 660 tonnes pour les Chaoborides. Le comportement d'essaimage des mouches du lac etait en forte correlation avec le cycle de la lune, et les adultes etait faciles a capturer pendant la nuit avec des lampes a kerosene. Des test biochemiques de la valeur nutritive des mouches du lac demontraient une haute contenance enproteine(62%),mineraux(18%), unefaiblecontenancedegras(3.9%)etd'eau(9%).Ced rend la mouchedu lac une addition ideale pour la nutrition d'animaux,et des experiences avec des poules et aquaculture de poisson sont en cours, pour etudier la faisabilite d'utiliser cette mouche comme ingredient dans les nutritiments pour animaux. 137 138 J. OKEDI

Comparison of growth, diet and food consumption of sea‐run and lake‐dwelling Arctic charr

“…had lipid contents of 70 and 50% (of dry weight), respectively, in July and August in northern Norway (Falk-Petersen et al, 1990). This is two to seven times the lipid content found in most invertebrate prey in fresh water (Hanson et al, 1985;Okedi, 1992;Goedkoop et al, 1998). Thus, eating the same amount of food in the sea as in fresh water, a sea-run fish will gain more energy and weight due to the higher lipid levels in the marine diet.…”

African edible insects for food and feed: inventory, diversity, commonalities and contribution to food security

“…A variety of insect species is the natural feed source for fish and poultry and can be exploited for this purpose (DeFoliart, 1989;Farina et al, 1991;Okedi, 1992). The amino acids derived from most insects' protein are superior to those from plant supplements in poultry feed formulations (Bukkens, 2005;Ravindran and Blair, 1993).…”

Cross-modality priming of visual and olfactory selective attention by a spider that feeds indirectly on vertebrate blood

“…For E. culicivora, satisfying a highly precise predatory preference may be particularly challenging. Mosquitoes, although plentiful in its habitat, are vastly outnumbered by other mosquito-sized dipterans, with non-biting midges, known locally as 'lake flies', from the families Chaoboridae and Chironomidae (Okedi, 1992) being especially common. Although E. culicivora eats lake flies as well as mosquitoes, the majority of its prey in nature is blood-carrying mosquitoes (Wesolowska and Jackson, 2003).…”