Host-mediated environmental microbiome recruitment by black soldier fly (Hermetia illucens) enhances waste biotransformation

Abstract

The black soldier fly larvae (BSFL) have demonstrated the ability to convert organic waste into high-quality proteins, lipids, and chitin on an industrial scale. This study aimed to examine the influence of exogenous microbes on the growth and development of BSFL by comparing Germ-free and normal BSFL that were reared on different substrates. Furthermore, the research evaluated the effects of microbes associated with the eggs. The results demonstrated that BSFL actively recruited specific functional microbes from their environment to facilitate growth and developmental processes. These recruited exogenous microbial consortia, originating from artificial substrates, kitchen waste, chicken manure, and egg-carrying microbiota, significantly enhanced Germ-free BSFL performance through improved larval viability, increased material conversion efficiency, elevated average body weight, and reduced pupal stage duration compared to Germ-free groups. The isolation and functional validation of intestinal microbiota identified Enterococcus, Bacillus, and Lactobacillus as core taxa for consortium formulation. This synthetic microbial community exhibited robust growth-promoting effects on BSFL, with maximal efficacy observed in chicken manure bioconversion systems, achieving 72.1 %, 193.6 % and 439.59 % enhancements in larval survival, biomass accumulation and feed conversion rate, respectively, alongside a 62.4 % reduction in prepupal development time compared to non-inoculated controls. Mechanistic analysis revealed a host-driven microbial recruitment strategy wherein BSFL selectively enriched functional symbionts to optimize environmental adaptation. These mutualistic interactions enhanced larval niche specialization and waste metabolic capacity, demonstrating scalable potential for circular waste valorization and sustainable bioremediation protocols.