During the COVID-19 pandemic, governments and health authorities worldwide implemented 'social distancing' rules, such as maintaining a distance of over 1.5 meters and banning various gatherings, to curb the spread of infection. Surprisingly, it has been discovered that ants also exhibit 'spatial immunity' by making their nests larger or altering their layout to reduce the spread of infectious diseases.
A research team led by Luke Leckie at the University of Bristol's School of Biological Sciences in the UK has confirmed that ant colonies alter their nest structure when exposed to pathogens, publishing their findings in the journal 'Science' on the 16th (local time).
Building layouts and transportation networks shape human interaction patterns. This is why spatial structures influence the transmission of infectious diseases through contact. Historically, cities were expanded or functionally zoned during pandemics like the Black Death or cholera. However, active modification of space by non-human animals in response to infectious disease had not been confirmed until now.
The research team designed an experiment to see how the black garden ant (*Lasius niger*), which builds complex nests and lives in societies much like humans, responds to infectious diseases. The team introduced 20 worker ants infected with the fungus *Metarhizium brunneum* to a digging site where 180 worker ants were building a nest. This is a common pathogenic fungus transmitted through contact.
Over the next six days, they analyzed how the nest structure changed using 3D computed tomography (CT), revealing structural differences compared to a control group that received 20 healthy worker ants.
The pathogen-exposed group expanded its nest more rapidly and increased the distance between entrances compared to the control group. The distance between chambers grew, while connectivity decreased. This arrangement is inefficient for movement but effective at preventing disease transmission. Simulations of infection spread based on each nest structure showed that the architectural changes did indeed reduce pathogen transmission.
The researchers stated, "This implies that ants modify their nest structure to defend against disease," adding, "It shows how social animals utilize their surrounding environment to respond to external stressors."
<Reference>
- doi.org/10.1126/science.ads5930
