Growth performance of black soldier fly larvae cultured at varying stocking densities on brewery waste.

Abstract

Aquaculture sector contributes greatly to the livelihoods of households in Uganda through provision of food and employment. In an attempt to reduce feed costs in aquaculture, many farmers have resorted to culturing of black soldier fly (BSF), Hermetia illucens larvae on locally available substrates with brewery wastes presenting very good results. Hence, this study assessed the growth performance of BSF larvae reared at four varying stocking densities (40, 80, 120 and 160/kg) in brewery wastes. Random samples of 20 larvae were collected and weighed using an electronic weighing scale. The number of larvae were counted in each container to determine the survival rate. The findings indicate that the stocking density of 80 larvae per kilogram substrate produced the heaviest larvae. At 80 individuals per kilogram (kg), the substrate provided sufficient nutrients for the growth of the larvae. In addition, the substrate kept loose enabling the downward feeding of the larvae hence, efficient nutrient utilization. The larvae presented high survival rates across all treatments with the highest being 93% (160 larvae per kg) and lowest, 87% (40 larvae per kg). The high survival rates was due to physiochological adjustments enabling the larvae to survive at low and high densities. The substrate structure and larval distribution varied across the stocking densities from loose to blocky and random distribution to aggregation, respectively due to the moisture content of the substrate. Further studies to determine the nutritional composition of the BSF larvae raised at the investigated stocking densities is recommended.