Ants change the structure of their nests when exposed to pathogens.

For example, limiting social contact through social distancing is considered an effective barrier to preventing the spread of disease.Serial Number: March 13, 2020) Humans also alter what researchers call spatial networks, using buildings or parts of cities as quarantine zones or expanding urban space.

To see if ants behaved in a similar way, Nathalie Stroeymeyt and her team at the University of Bristol in the UK had 20 groups of 180 black garden ants dig nests in jars filled with dirt. The day after digging began, the researchers added 20 more worker ants to each jar, and half of the jars were given a group infected with a fungal pathogen.

The researchers then monitored the ants’ behavior via video over the next six days and studied the evolution of the nests using micro-CT scans.

Ant colonies exposed to the pathogen dug their nests faster than healthy colonies, initially built more tunnels, and made several structural modifications, including placing the entrances on average 0.62 cm farther apart after six days. The exposed colonies also placed the chambers that housed colony resources, such as queens, brood, and food, less centrally. And the fungus-infected ants spent more time on the surface than their peers, which the study suggests may be a form of self-isolation.

The team then used spatial network analysis and disease transmission simulations to see if the changes had any noticeable effect on how the disease spread in the nests. Using designs created from exposed and unexposed colonies, the team simulated what would happen if the pathogen was introduced. The redesigned colonies, which were resistant to the disease, had significantly lower fungal burdens and lower mortality than colonies created from nests without prior exposure to the disease.

The findings are intriguing, if not surprising, says Sebastian Stockmeier, a behavioral disease ecologist at the University of Tennessee, Knoxville. He says social insects such as ants, bees, and termites have evolved a variety of colony-level defenses to effectively manage disease, and large outbreaks are rare.

Group living is generally thought to increase disease risk, and this threat is particularly pronounced in social insects, which have low genetic diversity and frequent social interactions, factors that help diseases spread. Because of this, when faced with disease, “their strategies are generally focused on protecting the group as a whole rather than focusing on individuals,” Stockmaier says.