Effects of different tissue substrates on the development and gut microbiota of <i>Sarcophaga peregrina</i> (Diptera: Sarcophagidae)

Developmental data from necrophagous flies are widely used to estimate the minimum postmortem interval (PMImin), but their reliability may be affected by larval feeding substrate and associated gut microbiota. Under controlled laboratory conditions, we investigated the effects of three porcine tissues (liver, lung, and muscle) on the development and gut microbial communities of Sarcophaga peregrina (Robineau-Desvoidy) (Diptera: Sarcophagidae). Developmental duration, larval body length, and pupal length were recorded, and gut samples from six developmental stages were analyzed by 16S rRNA gene sequencing. Feeding substrate affected development mainly during the feeding stages, with the second instar showing the greatest sensitivity. Larvae reared on liver developed significantly faster than those reared on muscle, whereas maximum larval length did not differ among groups; pupae from the liver group were significantly larger. Gut microbiota analysis showed that developmental stage was the primary driver of community succession, while feeding substrate further shaped microbial divergence during feeding. The dominant bacterial phyla across samples were Pseudomonadota, Bacillota, and Bacteroidota. The liver-fed group was enriched in Bacillota-associated taxa, including Vagococcus, Lactococcus, and Peptostreptococcus, whereas the lung- and muscle-fed groups showed greater enrichment of Wohlfahrtiimonas, Ignatzschineria, and Providencia. LEfSe, functional prediction, and random forest classification further supported clear substrate-associated differences. These findings show that tissue substrate influences both development and gut microbial succession in S. peregrina and may affect PMImin interpretation.