Architectural immunity: Ants alter their nest networks to prevent epidemics

In animal groups, spatial structure shapes social interaction patterns, thereby influencing the transmission of infectious diseases. Active modifications to the spatial environment could therefore be a potent tool to mitigate epidemic risk. We tested whether <i>Lasius niger</i> ants modify their nest architecture in response to pathogens by introducing control- or pathogen-treated individuals into nest-digging groups and monitoring three-dimensional nest morphogenesis. Pathogen exposure led to architectural changes, including faster nest growth, increased interentrance distance, transmission-inhibitory changes in nest network topology, and reduced chamber centrality. Simulations confirmed that these changes reduced transmission and highlighted a synergy between architectural and behavioral responses to disease. These results provide evidence for architectural immunity in a social animal and offer insights into how spatial organization can be leveraged to decrease epidemic susceptibility.