Ants changed the architecture of their nests when exposed to a pathogen

Amazing stuff!

"... Several animals are known to alter their behavior to avoid infections, including humans, guppies and mice. But these are the first nonhuman animals shown to actively alter their surroundings in response to infections, researchers report September 2 in a paper posted at bioRxiv.org. ...

To see whether ants act in a similar way, ... team ... let 20 groups of 180 black garden ants excavate nests in soil-filled jars. The day after digging started, the researchers added 20 more worker ants to each jar, with half of the jars receiving groups infected with a fungal pathogen.

Over the next six days, the researchers used video to monitor the ants’ behavior and micro-CT scans to study the evolution of their nests.

Ant colonies exposed to the pathogen dug nests faster and initially made more tunnels than healthy colonies, and after six days, had made several structural modifications, including spacing entrances 0.62 centimeters farther apart on average. The exposed colonies also placed chambers — which house colony resources such as queens, their brood and food — in less central locations. And ants infected with the fungus spent more time at the surface than their coworkers, which the study suggests is probably a form of self-isolation. ...

The team then used spatial network analysis and disease transmission simulations to see if the changes would have any noticeable impact on the way disease would spread in the nests. Taking the designs crafted by the exposed and unexposed colonies, the team simulated what would happen if a pathogen was introduced. Ant colonies in the disease-resistant redesigns would have a significantly lower fungal load — and fewer lethal doses — than those in nests built without any previous exposure to disease, the team found. ..."

From the abstract:

"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 controlor 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."

Ants changed the architecture of their nests when exposed to a pathogen "Tweaks to entrances, tunnels and chambers may help prevent diseases from spreading"

Architectural Immunity: ants alter their nest networks to fight epidemics (open access, pre-print)

Fig. 1 Experimental protocol and nest network extraction.