Immunity of the black soldier fly (Hermetia illucens): recent progress and technological applications

The black soldier fly (BSF, Hermetia illucens) is a keystone for sustainable waste bioconversion and alternative protein production, and its tolerance to microbially rich substrates reflects a robust innate immune system. Most of the recent advances in our understanding of BSF innate immunity have been published between 2020 and 2025; this review synthesizes those recent findings across molecular, cellular, and ecological scales. BSF larvae deploy rapid cellular defenses, such as phagocytosis and encapsulation, supported by a broad and dynamic humoral arsenal-including dozens of antimicrobial peptides (AMPs), lysozyme, and melanization factors-that are often strongly induced following microbial challenge. Conserved signaling modules (Toll/Imd-like cascades and dual oxidase-mediated pathway) shape both systemic resistance and gut microbial composition, while the resident microbiota contributes to pathogen suppression. Noteworthy, nutrition and environment can markedly shape BSF immunity: for example, nutrient-poor diets alter AMP expression and hemocyte numbers, while microbe- or fungus-rich substrates induce distinct AMP production and cellular responses. In general, BSF can reduce zoonotic pathogen load in the rearing substrate, BSF-derived AMPs act against antibiotic-resistant bacteria, and BSF-based feedstuffs enhance immune markers in livestock-biosecurity and development of value-added BSF-based bioproducts. Modern tools (high-quality genomes, transcriptomics, proteomics, RNAi, and CRISPR) now permit precise functional dissection of immune mechanisms in this insect, but key gaps remain, including antiviral and antiparasite defenses, the roles of JAK/STAT signaling, and mechanisms of immune ontogeny. Building on this synthesis, we identify critical knowledge gaps and propose prioritized research and applied actions to improve biosecurity and advance BSF bioproduct development.