Valuable Properties of Chitosan-Enriched Extracts from Black Soldier Fly Pupal Exuviae as Plant Biostimulants

Chitin, a prevalent polysaccharide in fungal cell walls, insect exoskeletons, and crustacean shells, is traditionally extracted from crustacean shells. However, aligning with circular economy principles, there is growing interest in utilizing bioconverter insects like the black soldier fly (Hermetia illucens). We explored the potential of H. illucens pupal grown on discarded agro-industrial waste to obtain enriched chitosan sources for plant biostimulants and protectors. Chitin was extracted from the pupal exuviae, and the properties of bleached (ChB) and nonbleached (ChU) chitosan fractions were compared. Both fractions exhibited structural similarities to commercial chitosan, with ChU showing a superior antioxidant capacity. In hydroponic lettuce cultivation, ChU significantly increased the biomass and chlorophyll content, while ChB had no notable effect. Both ChU and ChB activated auxin signaling in a transgenic tomato model and exhibited fungicidal activity against Fusarium solani f. sp. eumartii. These findings indicate that H. illucens pupal exuviae, cultivated on discarded agro-industrial waste, offer a valuable alternative for use as a plant biostimulant. This type of research forms the foundational basis for recognizing the potential of waste as a resource to innovate and create various products aligned with the circular economy strategy.