| Summary: | Black soldier fly (BSF) larvae are often exposed to organic waste which harbors abundant zoonotic pathogens. We investigated the ability of BSF larvae to inhibit the zoonotic pathogens naturally found in pig manure. The zoonotic pathogens populations were detected by using selective medium during the conversion. Results showed that the viability of the zoonotic pathogens in pig manure was significantly affected. After eight days of conversion, the <i>Coliform</i> populations were undetected, and <i>Staphylococcus aureus</i> and <i>Salmonella</i> spp. decreased significantly on the eighth day. Antimicrobial assays of the purified recombinant defensin-like peptide 4 (DLP4) showed that this peptide exhibits inhibitory activity against <i>S. aureus</i>, <i>Salmonella enterica</i> serovar typhimurium, and <i>Escherichia coli</i> in vitro. Bacteria BSF-CL and BSF-F were isolated from the larvae gut, and both inhibited the growth of <i>S. aureus</i> and <i>E. coli</i>, but <i>Salmonella</i> spp. was sensitive to the BSF-CL strain (but not to the BSF-F strain). The results from our experiments indicate that BSF larvae are capable of functionally inhibiting potential zoonotic pathogens in pig manure through a variety of mechanisms including antimicrobial peptides expression and the gut associate microorganisms. This study provides a theoretical basis for further study on the combined mechanism of BSF larvae immunity and its gut microbes against the zoonotic pathogens in pig manure.
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