Architectural immunity: ants alter their nest networks to prevent epidemics

In animal groups, spatial heterogeneities shape social contact networks, thereby influencing the transmission of infectious diseases. Active modifications to the spatial environment could thus be a potent tool to mitigate epidemic risk. We tested whether Lasius niger 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 over time. Pathogen exposure led to an array of architectural changes including faster nest growth, increased spacing between entrances, transmission-inhibitory changes in overall nest network topology, and reduced chamber centrality. Simulations confirmed that these changes reduced disease spread. These results provide evidence for architectural immunity in a social animal and offer insights into how spatial organisation can be leveraged to decrease epidemic susceptibility.