Nature Microbiology, Published online: 24 August 2026; doi:10.1038/s41564-026-02448-7 Colibactin, a microbially produced genotoxin linked to colorectal cancer, can inhibit pathogen colonization while favouring bacteria that tolerate its genotoxic activity, uncovering an ecological role for colibactin in shaping microbial communities in the honey bee gut.