Metabolomics of susceptible and insecticide-resistant strains of Spodoptera frugiperda (Lepidoptera: Noctuidae) and metatranscriptomics of their midgut-associated microbiota.

The gut microbiota of insects can influence host physiology and, like the host, can be affected by stressors. In this study, we investigated the effects of insecticide exposure on the metabolome and gut microbial metatranscriptome of insecticide resistant and susceptible Spodoptera frugiperda larvae. Metabolomic analysis revealed distinct metabolic profiles influenced by host phenotype and treatment with three insecticides: flubendiamide, spinosad and teflubenzuron. Amino acids, monosaccharides and fatty acids were prominent among the differentially abundant metabolites. Insecticide exposure altered the interactions between the host and its microbiota in an insecticide-dependent manner. Phenotype emerged as an important factor influencing the metabolic profile of S. frugiperda in response to insecticide exposure. For certain metabolites, this influence is observed constitutively, independent of treatment. This study highlights the role of members of the gut microbiota contributing with metabolites involved in host detoxification. In addition, it demonstrates that insecticide exposure and resistance evolution may alter host immunity and its interaction with the gut microbial community. Our findings help to clarify the complex interplay between insecticide exposure, gut microbiota, and host response, and provide insights into the dynamics of the gut microbiota of S. frugiperda in response to insecticides.