Performance of the Black Soldier Fly (Diptera: Stratiomyidae) on Vegetable Residue-Based Diets Formulated Based on Protein and Carbohydrate Contents

The black soldier fly [Hermetia illucens L. (Diptera: Stratiomyidae)] can be sustainably reared on organic waste streams and thereby provide a novel animal protein source for animal feed. Black soldier fly's performance and body composition depend to a large extent on the nutrient composition of the waste stream. Black soldier fly larvae were fed on four diets consisting of vegetable by-products from the food industry. All four diets contained dried distiller's grains with solubles plus one or two other main ingredients; for diet 1 the additional ingredient was grape pulp; diet 2: potato peels; diet 3: bean seeds; and diet 4: cabbage leaves plus old bread. The diets were formulated based on an optimal summed protein and carbohydrate (P+C) concentration resulting from previous experiments and a 1:2 protein: carbohydrate (P:C) ratio. We quantified both larval and adult performance. Diet 4 was the best performing vegetable waste-based diet. In a follow-up experiment, we re-formulated diet 4 to have P: C ratios of 1:2 or 1:3 and 40 or 47% dry matter of P+C. In the first experiment, although there were differences in larval performance among the diets, all diets supported a higher larval performance than reported previously, with diet 4 having 47% P+C being the best performing diet. We infer that not only total macronutrient content but also nutritional quality of proteins and carbohydrates affected performance. In the second experiment, the two vegetable residue-based larval diets resulted in similar larval and adult performance. High dietary protein resulted in increases in larval crude fat content.