Reconstruction of Gut Bacteria in Infected by Affects the Survival of Host Pest.

(Lepidoptera: Noctuidae) is a migratory agricultural pest that is devastating on a global scale. is a filamentous entomopathogenic fungus that has a strong pathogenic effect on Lepidoptera pests but little is known about the microbial community in the host gut and the dominant populations in fungus-infected insects. AJS91881 was isolated and identified from the infected larvae of . The virulence of AJS91881 to the eggs, larvae, pupae and adults of was measured. Moreover, the gut microbial community diversity of healthy and fungus-infected insects was analyzed. Our results showed that after treatment with AJS91881, the egg hatching rate, larval survival rate and adult lifespan of the insects were significantly reduced, and the pupae rigor rate was significantly increased compared to that of the control group. Additionally, the gut microbial community was reconstructed after infection. At the phylum and genus level, the relative abundance of the Proteobacteria and increased significantly in the treatment group. The KEGG function prediction results showed that fungal infection affected insect gut metabolism, environmental information processing, genetic information processing, organism systems and cellular processes. Fungal infection was closely related to the metabolism of various substances in the insect gut. was the bacterium with the highest relative abundance after infection by ; intestinal bacteria inhibited the infection of insect fungi against the . The presence of gut bacteria also significantly reduced the virulence of the fungi against the insects when compared to the group with the larvae fed antibiotics that were infected with fungal suspension (Germfree, GF) and healthy larvae that were infected with fungal suspension prepared with an antibiotic solution (+antibiotic). In conclusion, the reconstruction of the insect intestinal bacterial community is an indispensable link for understanding the pathogenicity of against . . Most importantly, in the later stage of fungal infection, the increased abundance of in the insect intestine inhibited the virulence of to some extent. The findings aid in understanding changes in the gut microbiota during the early stages of entomopathogenic fungal infection of insects and the involvement of insect gut microbes in host defense mediated by pathogenic fungal infection. This study is also conducive to understanding the interaction between entomopathogenic fungi, hosts and gut microbes, and provides a new idea for the joint use of entomopathogenic fungi and gut bacteria to control pests.