Larvae of Black Soldier Fly upcycle pig manure into highly valuable fat and proteins on the farm

This study aimed to optimize the rearing process of black soldier fly larvae on solid pig manure on the farm. The optimal rearing conditions were first studied in climate rooms. Larvae were grown at 21-24-27°C and feeding frequency and feed dose were varied. Then, pilot scale bioconversion units were constructed and evaluated on the farm. Active ventilation was applied. Emissions were monitored and mass balances were made. Rearing BSF larvae on pig manure on farm was possible without additional heating and yielded larvae of 27-33% DM, 45-50% protein and 20-24% fat (lab & pilot scale). Ventilation appeared to be crucial to enable automatic harvesting of the full-grown larvae. Increased levels of NH3, CO2 and CH4 were measured compared to indoor air. Bioconversion rates of DM amounted to 13% (max. 15%) at lab scale and to 9-12% at pilot scale. Further optimization of insect rearing on farm is necessary and special attention is required for emission control and economic feasibility.