After ingestion, the gut microbiota can metabolize xenobiotics, and xenobiotic exposures can lead to changes in the microbiota. Wang et al. exposed the model wasp species Nasonia vitripennis to subtoxic levels of atrazine, a widely used pesticide, and observed changes in the structure and function of the gut microbiome that confer multigenerational host resistance to the pesticide. The authors performed multi-omics analyses on laboratory populations of N. vitripennis and observed changes in dominant members of the microbiota that were also inherited by subsequent, unexposed generations. Two members of the gut microbiota — Pseudomonas protegens and Serratia marcescens — became enriched after atrazine exposure, were found to metabolize atrazine and were sufficient to confer resistance in wasps. As Nasonia species maternally inherit their microbiota, this study suggests an inability to return to an ancestral-like microbiome pre-atrazine exposure.