Amino acid requirements of mealworm and black soldier fly larvae

The amino acid requirements of each animal depends on the species and on its phase of growth. The diet should therefore vary according to the animals’ needs. The essential amino acid requirements of most farm animals have been extensively studied and diets have been formulated that fully meet their needs. Knowing the amino acid requirements of the most commonly reared insects for feed and food purposes could further optimise this innovative breeding sector. Based on this question, the amino acid requirements of the 2 most common species of farmed insects, mealworms (MW, Tenebrio molitor) and black soldier fly larvae (BSFL, Hermetia illucens) were studied in this project. According to needs of pigs and evidence found in the literature, it was decided to focus on insect requirements of lysine, methionine, threonine, phenylalanine and tryptophan. Based on these assumptions, semi-artificial diets with a base of 25% wheat bran for MWs and chicken feed and water (30/70) for BSFLs supplemented with sugar and 14 synthetic amino acids (the 10 essential amino acids for mammals + glutamic acid, glycine, alanine and aspartic acid) were formulated. All the diets were isoenergetic and isonitrogenic. Of the five amino acids studied, one was given in different doses for each experiment. Glutamic acid, which is not essential, was used as a substitute for the amino acid examined. Finally, growth (measured by weight gained) and survival rate were measured. For lysine no additional growth was noted from a content of 0.35 g/100 g. For methionine the value was from 0.13 g/100 g. For what concerns the threonine a significant difference was noted as the amount increased and the minimum dose appeared to be 0.42 g/100 g. With tryptophan the level of inclusion did not lead to differences and at 0.06 g/100 g the maximum growth had already been reached. In conclusion, a report with the optimal formulation standards and guidelines will be drafted with a focus on the use of the results of this research in the formulation of optimal diets with attention to environmental sustainability.