Characterization of Gut Bacteria in Blepharipa tibialis (Diptera: Tachinidae) Larvae Parasitizing Different Developmental Stages of Antheraea pernyi

Blepharipa tibialis (Diptera: Tachinidae) is a typical parasitoid fly. It spends most of its lifespan inside its host (Antheraea pernyi larvae) and relies heavily on host nutrition for survival. Whether the gut bacteria characteristics of B. tibialis larvae are associated with host development during the parasitoid process remains unclear. In this study, we used high-throughput sequencing to conduct the first systematic investigation of the gut bacteria of a parasitoid fly, comprehensively revealing the composition, structure, diversity, specificity, and potential functions in B. tibialis larvae parasitizing different host developmental stages. Results show that B. tibialis larval gut bacterial species were highly abundant, with a total of 24 phyla, 41 classes, 84 orders, 127 families, and 194 genera annotated. Although the number of bacterial species in B. tibialis larvae parasitizing different host stages (3rd, 4th, and 5th instar) differed significantly, the community structures were similar, suggesting that host physiological changes and dynamic alterations in the internal microenvironment may drive changes in the larval gut bacteria. Different host developmental stages may alter the gut bacterial composition of B. tibialis larvae, but bacterial functional stability is largely maintained. PICRUSt2 functional prediction indicated that the gut bacterial community may play an important role during the parasitoid process of B. tibialis larvae. This study provides an important basis for research on gut bacteria in tachinid flies (Diptera), supplements gut microbiota data for this group, and offers references for exploring the interaction mechanisms of gut microbiota in parasitoid systems, as well as for developing green control strategies against A. pernyi pests.