Brewery’s waste streams as a valuable substrate for Black Soldier Fly Hermetia illucens (Diptera: Stratiomyidae)

The growing population and, consequently, the demand for food, has led to an increase in the agro-food activities, causing irreversible exploitation of natural resources. The use of insects for the management and recycling of by-products of the agro-food industry and for the production of proteins is growing. The Diptera Hermetia illucens is of particular interest as larvae are able to grow rapidly on numerous organic matters and are rich in proteins and fats. The identification of a low-cost and low-impact substrate suitable for the mass rearing of H. illucens is consequently of great interest. In this study, we evaluated the suitability of brewery wastes, spent grain and trub (used separately or mixed), as rearing substrate for the larvae. We evaluated the effect of these diets on preimmaginal performance (survival, developmental time, and weight reached) and adult traits (sex-ratio, dimension, and female fertility). As a result, the different substrates significantly impacted different biological traits. Best results, both for larvae and adults, were reported when the brewery wastes were provided together, leading to similar results obtained in a control diet and comparable to other previous studies. We conclude that brewery by-products can be valuable substrate for larval growth and in this way can be efficiently recycled and valorised.