Black Soldier Fly Larvae
The use of the Black Soldier Fly Larvae or BSFL (Hermeticia illucens ) for conversion of organic waste streams into valuable animal protein has now become a hot topic.
BSFL are capable of processing livestock manure, human faecal waste, food waste, fermented maize straw without difficulty. BSFL are utilised as an animal feedstuff due to their valuable nutritional profile. Larvae are reported as consisting of +- 40% protein and +- 35% fat, depending on the feeding substrate of the. They also have an amino acid profile closely resembling fish meal making them an ideal alternative to expensive fish meal in omnivorous fish farming. Studies feeding BSFL as part of other feedstuffs to chicken, pigs, catfish and tilapia have demonstrated predominantly positive results.
Lastly, the adult flies are not a nuisance species or a mechanical disease vector, because the adult flies do not feed, living off fat stores, and female flies only ovipost on the edges of larval food sources avoiding contact with harmful pathogens . The presence of BSFL in waste also serves to deter oviposition of other species such as Musca domestica which do act as a vector to spread disease.
Different substrates affect BSFL composting in terms of larval growth (biomass conversion ratio, final larval weight), larval development time and waste reduction. Larval density, feeding rate and feeding frequency have a great impact on the efficiency of the process.
For use as feed, the protein content and the amino acid profile of the larvae/prepupae are important.
Mixing waste fractions that have a high protein content with fractions that are high in easily available carbon give sometimes better results than a pure substrate..
Large-scale protein production facilities treating up to 200 tonnes of waste per day are already in operation. On the other end of the spectrum are decentralised small-scale farmer systems motivated by the thought of self- sufficiency. In the middle of the scale are facilities treating up to 10 tonnes per day. There are benefits and constraints, with both large- and small-scale BSFL treatment facilities. However, by combining the advantages of the centralised large-scale production systems ( production of eggs) with the benefits of decentralised, rearing farmer units, many of the constraints can be overcome.
The guidelines for the application of BSFL for waste treatment indicate that a small-scale enterprise can treat 60 kg of bio-waste with 40.000 larvae on1 m2 over 12 days. One gram of egg can contain about 50,000 larvae, can produce 2-5 kg larvae.