Chitosan obtained from black soldier fly larval cuticles expands the value chain and is effective as a biocontrol agent to combat plant pathogens.

The industrial use of certain insects, such as the black soldier fly (BSF, Hermetia illucens), has become a burgeoning way of converting residual biomass into a valuable source of biomolecules for the feed and food industry. Here, the integration of a valuable step as an upcycling technology using biological waste from the 5th instar BSF larvae processing as a source of bioactive chitosan was explored. The goal is to pave the way for sustainable chitosan production from insect-based resources in addition to proteins, lipids, and fertilizers. The macronutrient profile of the larval waste was evaluated for chitosan extraction. After homogenization and mechanical separation of the larval pulp, enzyme-assisted extraction of chitosan from the chitin-rich matrix was performed using different combinations of commercially available proteases and lipases, followed by chemical deacetylation. The antifungal efficacy of the recovered chitosan varied depending on the extracted product and tested fungal plant pathogens. Furthermore, the plant priming effect of chitosan on Beta vulgaris promoted plant vigor and disease resistance. Seed coating resulted in improved germination and primary root growth. Thus, the extraction of chitosan from BSF larval cuticles offers an optimistic outlook for expanding the technological competence of the insect upcycling industries.