You live in a crowded underground city with everyone you know. A relative comes home and you may find that they have been exposed to something that could make you all sick. If this option is not checked, one disease can wipe out your entire civilization. So you do what needs to be done.
You lick it. A lot of.
At least that’s what it says do when you’re a termite Rebeca Rosengaus, Associate Professor and Behavioral Ecologist at Northeastern.
Rebeca Rosengaus, associate professor at the Institute of Marine and Environmental Sciences, studies how social insects prevent diseases from wiping out their colonies. Photo by Matthew Modoono / Northeastern University
Rosengaus has spent the past 30 years studying how social insects like ants and termites prevent diseases from wiping out their colonies. It’s the kind of scientific obsession that comes with watching an experiment go to pieces and determined to find out why.
As a graduate student at Boston University, Rosengaus created thousands of termite kings and queens with the perfect environment to grow new colonies. She tried to study the effects of inbreeding on outbringing.
“Everyone wants to get rid of termites. I actually bred termites, ”says Rosengaus. “I provided them with good humidity, good temperature, good wood and good filter paper – everything was perfect.”
But apparently not perfect enough. Sixty percent of their starter pairs died before they could form a colony – most of them succumbed to a fungal infection, Rosengaus found.
“I’ve lost all animals left and right that I wanted to set up for my inbreeding / outbringing experiments,” says Rosengaus. “I have my Ph.D. with thousands of colonies, and the 40 percent survivors are the ones I did my research on. But I still had this nagging question: why do they die so often after you’ve separated the reproductive caste from their birth nest? “
The warm, humid, subterranean environments where ants and termites thrive are also perfect for microbial growth. Social insects, which can live in groups of thousands and even millions of individuals in a single nest, have evolved group behaviors to protect each other and the entire colony from disease, says Rosengaus. These behaviors just aren’t effective outside of a large social network.
When an ant or termite returns to the nest with some sort of harmful microbe clinging to its exoskeleton, their nestmates will groom it furiously. Some termites have antifungal compounds in their saliva to kill the pathogen, and ingested microbes are either neutralized in the stomach or, in ants, trapped in a sieve-like structure in the throat, where they can be compressed into a pellet and later vomited.
The warm, humid, subterranean environments where ants and termites thrive are also perfect for microbial growth. Photos by Matthew Modoono / Northeastern University
This somewhat disturbing picture is only the first step in a complex and highly effective pathogen defense system. From here on it just gets weird.
When a termite returns with a fungal load too high to effectively lick, behavior changes. All infected termites begin to tremble and twitch as if they are in some kind of ritualized plague dance to tell everyone else to retreat.
“The nest mates who perceive the vibrations actually flee; They go far away from the source of the vibration, ”says Rosengaus. “So this is another way of telling another member of the colony that there are a lot of diseases here. Just go away.”
The healthy individuals can also start pooping near a diseased termite. How could that possibly help, you ask? It turns out that compounds in termite poop can kill pathogens.
“The research we did showed that the fecal material actually had antifungal properties,” says Rosengaus. “They poop all over the area when there are a lot of infectious particles, and by pooping on it, they cover it and deactivate it with the feces.”
Termites are voracious eaters. This birch trunk used to be solid, but after a few months with a termite colony it is just a circle of empty bark. Photo by Matthew Modoono / Northeastern University
And when that doesn’t work, there is always cannibalism.
“If you are too deep in the disease instead of allowing you to make everyone in the colony sick, they will only consume you,” says Rosengaus.
It makes physical distancing and wearing masks seem downright comfortable in comparison.
When a pathogen overcomes this behavioral protection, social insects also have an immune system that can fight off infection or encapsulate and neutralize invading microbes. And if, in some cases, they trigger an immune response, they can share it.
Imagine if you could get a vaccine that protects you from measles, for example, and then pass on your immunity to your partner through a French kiss. That’s essentially what carpenter ants do.
Social insects such as termites can live in groups of thousands and even millions of individuals in a single nest. They have developed several strategies to protect their colony from disease. Photos by Matthew Modoono / Northeastern University
Rosengaus and her colleagues found that infected carpenter ants produce an immune protein that helps them fight off disease. And the immune protein can be passed on to uninfected ants through “mouth-to-mouth burping,” which prepares your immune system to fight off pathogens to which you have not yet been exposed.
“They share their immune protection,” says Rosengaus. “And then it makes the entire colony less susceptible to the disease.”
Social insects have evolved these diverse strategies to resist disease for millions and millions of years in order to survive life in environments with potentially deadly pathogens. Maybe it’s time we learned from them, says Rosengaus.
“Imagine if you could only vaccinate one person in the household, and that person then creates an immune response that is transferable to family members,” says Rosengaus. “That could definitely improve vaccination compliance.”
Will it be about spitting food in someone else’s mouth?
“Well, there are worse ways to get socially vaccinated,” says Rosengaus. “You could potentially eat corpses to expose yourself to small amounts of a pathogen and try to develop an immune response that way.”
For media inquiriesPlease contact Shannon Nargi at s.nargi@northeastern.edu or 617-373-5718
