Black soldier fly (Hermetia illucens) larvae (BSFL) are emerging as a sustainable solution for converting agricultural waste into valuable resources. Here we show, BSFL grown on different agricultural wastes varying in yield and proximate composition, and their use as a fish feed ingredient, a source for anti-pathogens, and the application of BSFL growth residues for plant fertilization.
BSFL reared on vegetable, fruit, and leafy green wastes yielded in variable biomass of 62, 86 and 46 g wet weight per kg waste, respectively and 39, 29 and 47% protein and 43, 65 and 17% lipid content, respectively. Fish feeds with 10–20% vegetable waste-grown BSFL inclusions, supported Nile tilapia growth equivalent to standard diets. BSFL extracts exhibited antimicrobial activity, inhibiting growth of common fish bacterial (Streptococcus iniea, Vibrio sp.) and plant fungal (Botrytis cinerea, Rhizoctonia solani) pathogens. Lauric acid, a major fatty acid in BSFL, was linked to full ex vivo mortality of the parasitic fish worm Gyrodactylus turnbulli. Fish fed with BSFL feeds showed elevated lauric acid levels in liver and muscle tissue.
In plant growth experiments, 20% addition of BSFL growth residues (composed of frass and waste remains) as sole fertilizer, supported lettuce and basil growth comparably to the use of inorganic fertilizers, while broccoli yield was slightly reduced.
These results highlight the use of BSFL as a multifunctional platform for waste reduction and recycling, alternative protein production, disease control, and organic fertilization, offering significant improvement of circularity and sustainability in both, aquaculture and agriculture systems.
