AILSA CHANG, HOST:
Ants are many things. Like, they're very strong for their size, and they're intensely social. And, as Ari Daniel reports, they might be sources of architectural inspiration, too, for designing spaces that reduce the spread of disease.
ARI DANIEL, BYLINE: The ant in question is Lasius niger, the black garden ant.
NATHALIE STROEYMEYT: It lives everywhere in Europe, and you can just collect queens during the mating flight in July, which makes it very easy to work with.
DANIEL: This is Nathalie Stroeymeyt, a behavioral ecologist at the University of Bristol who studies how these ants deal with a deadly fungus.
STROEYMEYT: In order to successfully transfer, it needs to kill its host.
DANIEL: Transforming that host ant into something called a sporulating cadaver.
STROEYMEYT: It's basically completely covered in spores, and it's highly infectious.
DANIEL: Which puts any ants nearby in grave danger. Stroeymeyt has studied how these ants respond socially to the lethal fungus by gluing tiny squares of paper with QR-like codes to their thoraxes to track the individual ants' movements over time. First, she saw that infected workers quickly self-isolate.
STROEYMEYT: They spend more time out of the colony to prevent contamination of their nest mates.
DANIEL: In addition, some of the healthy ants, the nurses that care for the queen, eggs and larvae, increase their distance from the foragers.
STROEYMEYT: Which are the ones who go outside and are more at risk of contracting a disease - this was a form of proactive social distancing, if you wish.
DANIEL: Combined, this work revealed the ants alter their social behavior to protect themselves from an epidemic and safeguard high-value members of the colony.
STROEYMEYT: And that happens even when the nest is as simple as it can be with a single chamber. But in reality, they occupy these nests made of hundreds of chambers connected by thousands of tunnels.
DANIEL: Stroeymeyt wondered whether the ants also shift how they build and excavate their nests when threatened by a pathogen. She teamed up with Luke Leckie, now a systems biologist at Indiana University, to investigate. He gave small colonies a day to start building their nests before introducing ants infected with the fungus.
LUKE LECKIE: We were taking CT scans of the nests. They let us see the three-dimensional structure of the nest as it's developing over time.
DANIEL: Within six days, there were clear differences between the nests exposed to the pathogen compared to those that were not - differences that, according to computer simulations, appeared to help slow down disease transmission.
LECKIE: They were kind of more compartmentalized, and they were less interconnected.
DANIEL: Nest entrances were also spaced farther apart. Travel routes were longer, making the nests less efficient. But these structural changes enhanced the previously documented social response of the ants to isolate. Here's Nathalie Stroeymeyt again.
STROEYMEYT: It's the first demonstration of social species outside of humans who actively modifies the spatial structure of the environment in face of a threat. That, I find, is absolutely fascinating.
DANIEL: The results are published in the journal Science. Sarah Kocher is an evolutionary biologist at Princeton University who wasn't involved in the study. She says the findings deepen our understanding of something called social immunity found among many types of ants and bees.
SARAH KOCHER: Instead of relying on their individual immune systems, they work together as a group to try to minimize disease spread.
DANIEL: In addition, Kocher believes these ants have something to teach us.
KOCHER: Some of the principles could easily be applied to the way that we're designing public spaces that could help us prevent disease spread as well.
DANIEL: Principles like protecting more vulnerable members of the community and isolating sections of an enclosure. Think of it as architectural immunity delivered not by antibodies, but by ant bodies. For NPR News, I'm Ari Daniel.
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