Assessing Substrate Utilization and Bioconversion Efficiency of Black Soldier Fly (Hermetia illucens) Larvae: Effect of Diet Composition on Growth and Development Temperature.

Simple Summary: The increasing world population generates a huge volume of food waste. The use of black soldier fly larvae in the bioconversion of food waste is a new approach and an interesting example of a sustainable, circular economy approach. In this study, different food waste and residues (ranging from a vegetable to a carnivorous diet) were used as rearing substrates for black soldier fly larvae. The effects of different substrates on larvae development, bioconversion efficiency, and variations in surface temperatures were investigated. The results highlighted how an omnivorous diet provides performances comparable to the high-quality substrate diet (commercial chicken feed) and, therefore, can represent an effective strategy for rearing larvae while reducing food waste. Black soldier fly larvae (BSFL) can utilize food by-products or residues for growth, benefiting farm animal's diets' production sustainability. The experiment aimed to assess the effect of different substrate compositions on larval growth, chemical composition, and substrate temperature. BSFL were allocated to one of the four diets (control, vegetable, carnivorous, and omnivorous) for the entire experiment (8 days). The temperature was measured twice daily using a thermal-imaging camera, and the accumulated degree hours (ADH) was calculated. The results showed that the larvae fed the vegetable diet exhibited a significantly reduced growth performance, with a biomass reduction of 26.3% compared to the control diet; furthermore, vegetable-fed larvae showed a lower dry matter content (−30% compared to the average of other diets) due to lower fat content (−65% compared to average of other diets). The nutritional composition of larvae fed an omnivorous diet was similar to larvae fed a high-quality substrate diet (control diet-chicken feed), indicating that the omnivorous diet could be an ideal solution for rearing BSFL larvae; however, the current European legislation prohibits the use of animal meal. The study also revealed that substrate temperatures did not have a discernible influence on larval growth, further emphasizing the importance of diet in BSFL rearing strategies. [ABSTRACT FROM AUTHOR]