Study on the Structure and Function of Intestinal Microorganisms in Silkworm Maggot Exorista sorbillans

ABSTRACT Insects have important symbiotic relationships with their intestinal microbiota. The intestinal microbiota is involved in or influences various processes in insects such as development, metabolism, immunity, and reproduction. Currently, research on the intestinal microbiota of parasitic insects is still in its early stages. The tachinid parasitoid Exorista sorbillans is a dipteran parasitic insect, with the silkworm (Bombyx mori) being its main host. Silkworms parasitized by E. sorbillans can suffer from severe silkworm maggot disease, which also poses a serious threat to sericulture. In this study, the intestinal microbiota of larval E. sorbillans at three instar stages was analyzed using 16S rRNA amplicon sequencing to explore the community composition of the intestinal microbiota. Additionally, using conventional culture methods, six cultivable strains were isolated and identified from the larval E. sorbillans on an antibiotic‐free LB medium, and four cultivable strains were isolated and identified from the hemolymph of parasitized silkworms. This study investigated the E. sorbillans from the perspective of intestinal microbiota, elucidating the composition and structural characteristics of the intestinal microbiota of the tachinid parasitoid, and preliminarily discussing the functional roles of several major microorganisms, which helps to further clarify the potential mechanisms of interaction between the parasitoid and the silkworm. • The composition and diversity of gut microbiota in E. sorbillans larvae exhibit instar‐dependent variations. • Microbial horizontal transfer may play an important role in the interaction between parasitoids and parasitized hosts. Summary The gut microbiota of Exorista sorbillans is mainly composed of Proteobacteria and Firmicutes. The composition and diversity of gut microbiota in E. sorbillans larvae exhibit instar‐dependent variations. Microbial horizontal transfer may play an important role in the interaction between parasitoids and parasitized hosts.