Ants alter their nest networks to prevent epidemics, study finds

Ants make a series of clever architectural adjustments to their nests to prevent the spread of disease, University of Bristol research has uncovered. 

The study, published today (Thursday, 16 October) in the journal Science, found the nests built by colonies exposed to disease had far more widely spread entrances and were more separated, with fewer direct connexions between chambers.

Study lead author Luke Leckie, a PhD researcher in Biological Sciences at the University of Bristol, said: “We already know that ants change their digging behaviour in response to other soil factors, such as temperature and soil composition. This is the first time a non-human animal has been shown to modify the structure of its environment to reduce the transmission of disease.”

Ants possess a range of behavioural responses to disease that help form a social immunity, from removing disease-causing fungal spores with parts of their mouth and spraying exposed colony members with disinfecting poison, to germ-carrying ants self-isolating to protect the wider colony.

In the wild, ants dig complex, three-dimensional nests with tunnels and chambers to fulfil different functions such as storing food or protecting their young. Researchers used micro-CT, an advanced 3D scanning technique, to uncover how germ-exposed ants excavate their nests compared to a healthy colony.

The researchers studied two groups of 180 worker ants, which were introduced to two soil-filled containers and began digging their nests. After 24 hours, 20 additional ants were added to each nest, with one group exposed to fungal spores. The ants were then left to dig for a further six days, and micro-CT scans were taken periodically.

Once the researchers had constructed 3D models of the nests, they ran simulations of the spread of disease. The simulations showed the modified nests reduced the risk of individuals being exposed to the disease at high, potentially lethal doses.

Through these architectural adjustments, the disease-exposed ants protect vulnerable compartments that hold food stores and their young.

Luke said: “One of our most surprising findings was that when we included ants’ self-isolating in the simulations, the effect of the self-isolation on reducing disease transmission was even stronger in germ-exposed nests than control nests.”

The study could inspire future human approaches to managing social spaces to account for the increased threat of epidemics.

Like ant nests, human cities are a complex network of spatial structures. Balancing the trade-off between flow of good things such as resources, information, and people, whilst limiting the transmission of disease is becoming increasingly important as the threat of epidemics grows worldwide.