The gut microbiota of Hermetia illucens drives chlortetracycline residue degradation through metabolic rewiring

This study investigated host–microbiota metabolic interactions in black soldier fly larvae ( Hermetia illucens , BSFL) during chlortetracycline (CTC) attenuation under control and CTC-residue feeding regimes. Integrated 16S rRNA gene sequencing and untargeted metabolomics were used to characterize gut microbial restructuring and larval metabolic responses to antibiotic exposure. CTC treatment significantly reduced bacterial richness, as indicated by lower Ace and Chao1 indices, while Shannon and Simpson indices remained unchanged, suggesting that richness declined whereas community evenness was largely maintained. Beta-diversity analysis showed clear separation between control and CTC-treated groups, confirming treatment-driven restructuring of gut microbial composition. Taxonomically, the gut microbiota remained dominated by Bacteroidota, Firmicutes, and Proteobacteria, while CTC exposure enriched Enterococcus , Providencia , Ignatzschineria , and Klebsiella during the key attenuation window. Functional prediction indicated increased contributions from amino acid metabolism, membrane transport, replication and repair, signal transduction, and fermentative processes under CTC stress. Metabolomic profiling further revealed marked separation between treatments and significant enrichment of pathways related to amino acid metabolism, glycerophospholipid metabolism, and ABC transporters, indicating coordinated metabolic reprogramming in response to antibiotic exposure. Correlation analysis linked Enterococcus , Klebsiella , and Moheibacter positively with several amino acid- and membrane-associated metabolites, whereas Dysgonomonas showed mainly negative associations. Together, these findings support a coupled host–microbiota response underlying CTC attenuation in BSFL and provide mechanistic insight into the potential application of BSFL-based systems for the bioremediation of antibiotic-contaminated organic wastes. These results also identify candidate microbial consortia and metabolic indicators for future process monitoring and optimization in insect-based waste treatment systems under tropical production conditions. • Chlortetracycline significantly reduces the diversity of gut microbiota in Hermetia illucens. • Enterococcus , Klebsiella , and Ignatzschineria may potentially degrade chlortetracycline in the Hermetia illucens gut microbiota. • Hermetia illucens increased the abundance of potential probiotics for antibiotic degradation. • Enterococcus and Klebsiella can promote metabolic pathways by improving nutritional balance during antibiotic degradation.