Gut Microbiota Dysbiosis Influences Metabolic Homeostasis in Spodoptera frugiperda

Insect gut microbiota plays important roles in acquiring nutrition, preventing pathogens infection, modulating immune responses, and communicating with environment. Gut microbiota can be affected by external factors such as foods and antibiotics. Spodoptera frugiperda (Lepidoptera: Noctuidae) is an important destructive pest of grain crops worldwide. The function of gut microbiota in S. frugiperda remains to be investigated. In this study, we fed S. frugiperda larvae with artificial diet with antibiotic mixture (penicillin, gentamicin, rifampicin, and streptomycin) to perturb gut microbiota, and then examined the effect of gut microbiota dysbiosis on S. frugiperda gene expression by RNA sequencing. Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria were the most dominant phyla in S. frugiperda. We found that the composition and diversity of gut bacterial community were changed in S. frugiperda after antibiotics treatment. Firmicutes was decreased, and abundance of Enterococcus and Weissella genera was dramatically reduced. Transcriptome analysis showed that 1,394 differentially expressed transcripts (DETs) were found between the control and antibiotics-treated group. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) results showed that antibiotics-induced dysbiosis affected many biological processes, such as energy production, metabolism, and the autophagy-lysosome signal pathway. Our results indicated that dysbiosis of gut microbiota by antibiotics exposure affects energy and metabolic homeostasis in S. frugiperda, which help better understand the role of gut microbiota in insects.