In response to the COVID-19 pandemic, humans implemented various public health measures, including social distancing and lockdowns, to curb the spread of the virus. Interestingly, it turns out that humans are not the only species to adjust their social interactions during times of health crises. A recent study published in the journal Science reveals that black garden ants, known scientifically as Lasius niger, modify their nest structures to mitigate the spread of disease.
The study”s lead author, Luke Leckie from the University of Bristol, noted that while ants are known for altering their digging patterns based on environmental factors like soil temperature and composition, this is the first documented instance of a non-human species changing its habitat to lower disease transmission risk.
Eusocial insects, such as ants, often experience high rates of pathogen spread due to their close-knit social structures. Ant nests are characterized by intricate designs featuring specialized chambers for food storage, brood care, and waste management. Researchers hypothesized that these complex underground networks could serve to isolate potential infectious agents.
To explore this idea, Leckie and his research team utilized advanced micro-CT scanning technology to monitor two groups of 180 black garden ants as they excavated nests within soil-filled containers. After a 24-hour period, the team introduced 20 additional ants to each container, with one group being exposed to fungal spores of Metarhizium brunneum. Over the subsequent six days, the researchers conducted periodic scans to create a comprehensive 3D model of each nest”s layout.
Analysis of the 3D models revealed that the ants exposed to the fungal spores made significant changes to their nest configurations. The entrances to their nests were, on average, positioned about 6 mm farther apart from one another, which decreased the likelihood of crowding at the surface. Additionally, these exposed colonies constructed chambers with longer and more convoluted pathways, placing them in less central areas of the nests. The ants also created multiple tunnels, presumably as alternative routes to reduce direct contact among individuals.
The study observed increased surface activity among the workers exposed to the pathogen, which likely indicates behaviors akin to self-isolation and social distancing. Spatial network analysis and simulations of disease spread based on the 3D models indicated that the redesigned nests effectively lowered the risk of infection exposure for individual ants. Leckie remarked, “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.”
This groundbreaking research highlights how even small social insects employ strategies reminiscent of human public health measures in the face of disease threats, showcasing the intricate behaviors evolved in eusocial species.
