Productivity, conversion ability, and biochemical composition of black soldier fly (Hermetia illucens) larvae fed with sweet potato, spent coffee or dough

Black soldier fly (Hermetia illucens) larvae (BSFL) is a sustainable protein and lipid source in the diets of terrestrial and aquatic animals. This is largely due to their ability to thrive on various waste products, but the food type greatly influences their productivity and nutritional value. In this study, BSFL (initial mean weight = 0.11 g) were fed sweet potato, spent coffee or dough for two weeks and the survival, growth, feed efficiency, and biochemical composition were assessed. The best bioconversion/material reduction was from dough. The dough also produced significantly larger/heavier BSF, but a significantly lower percentage of pre-pupae. Crude protein was significantly higher in BSFL fed spent coffee than either dough or sweet potato. Among the essential amino acids, leucine and valine in BSFL were significantly higher in the spent coffee or sweet potato compared to those fed dough. BSFL fed sweet potato had the highest percentage of lauric acid (C12), while both sweet potato and spent coffee elevated eicosapentaenoic acid (20:5n-3), which is beneficial to terrestrial and aquatic animals. Although each substrate was high in carbohydrates, these produced BSFL with a high-quality protein content comparable or even superior than some plant-based proteins. Overall, sweet potato produced BSFL with the best nutritional profile while supporting their growth.