eLife assessment
This article describes a novel mechanism allowing the insect Drosophila to combat pathogenic enteric pathogens while preserving the beneficial indigenous microbiota. The authors provide compelling evidence that oral infection of Drosophila larvae by pathogenic bacteria activate a valve that traps the intruders in the anterior midgut, allowing them to be killed by antimicrobial peptides. This important work substantially advances our understanding of pathogen clearance in the insect gut.