Watch an invading queen ant trick workers into killing their mother
In a chilling discovery, a usurper sprayed an ant queen with a chemical to make her workers attack her.
Move over, Game of Thrones—ants can turn armies against their leaders and use subterfuge to take over entire kingdoms, too.
A new study published in Current Biology documented the queen of an ant species dethroning the queen of another species using a technique worthy of the famed TV series: She tricks the worker ants into killing their own mother queen and then serving her as their new queen.
This chilling discovery did not originate with a professional scientist, but rather from an ant enthusiast. In 2021, Taku Shimada, who collects ants and conducts experiments on them in his house, observed this behavior and posted about it in an online blog. Three years later, ecologist Keizo Takasuka at Japan’s Kyushu University came across Shimada’s observation and asked him to document it with him in a scientific publication.
“I was so astonished and lost my voice when I read the blog,” says Takasuka.
While other examples of offspring turning against their mothers have been documented in the animal kingdom, this report represents a new pattern of matricide in nature, one in which the original “family” does not gain anything by killing their mother, says Takasuka. In this case, it’s only the parasitic ant, which is neither the children nor the mother, that receives “all benefits from matricide,” he says.
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How the drama unfolded
Queens of some ant species are known to invade and take over colonies by directly killing the host queen, or by turning workers against her in some ways. However, exactly why the workers betray their own queen mother was unknown.
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To find that out, Shimada collected a queen ant of Lasius orientalis, an ant species also known as “bad-smell ant’’ known to parasitize other ant species, from a field with his son and left it overnight in a small container with individuals of another ant species, Lasius flavus.
This simulates what usually happens in the wild when, before entering the nest, the intruder queen would usually acquire the odor of the colony to go unnoticed once inside it. Some species, for example, do it by rubbing their body against that of workers.
‘’For many species, the exact means of acquiring host odour remains largely unknown,’’ says Takasuka. In fact, it’s still unclear how Lasius orientalis does that in the wild.
The next day, Shimada moved the intruder queen close to the entrance of the Lasius flavus colony and closely watched what happened.
The intruder queen entered the colony undisturbed, camouflaged among workers thanks to the odor she acquired overnight. Some workers even began to feed her, and if any dared to attack her, she quickly flicked them away.
After spending hours inside the nest, the invading queen finally located her target: the mother queen of the colony. The usurper slowly approached the unsuspecting insect and then sprayed her with a fluid, which the authors suspect to be formic acid, from the invader’s own abdomen.
The mood quickly changed in the colony. The workers became agitated. That’s because the invader's abdominal fluid changed the host queen’s usual odor. Workers then identified her no more as their mother, but as a stranger and a potential threat. And so, the matricide began.
The workers began attacking their mother, and in the next 20 hours the intruder queen sprayed her a total of 15 times. “The more times she sprayed, the more violent the attack became,” the team writes in the paper.
After four days of rioting, the workers finished their job. They tore their mother’s body in half, recognized the intruder as their new queen and started taking care of her. A new reign had begun.
After about 10 days, the intruder queen started laying eggs, and after three months the first 300 hatched. While the two species initially coexisted in the colony, after about one year, all the workers in the colony, about 3,000, were the invader’s own Lasius Orientalis.
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Citizen science leading to discoveries
The study authors report a similar observation made by another ant enthusiast, Yuji Tanaka, co-author of the paper, who documented a queen from another species named Lasius umbratus seizing the throne of another ant species in a similar way.
In this case, the intruder grabbed a worker with its mandibles and rubbed it over her body to acquire the colony’s odor. She sprayed the host queen only two times.
‘’The study is very interesting, and it shows some really undocumented strategies,’’ says Mattia Menchetti, a myrmecologist at the Natural History Museum in Berlin, who was not involved in the study.
The findings also highlight the importance of citizen science, says Menchetti, and demonstrates how non-scientists’ fascination with the natural world can lead to new discoveries.
Even ant species that are quite widespread, like Lasius Umbratus, remain quite overlooked scientifically, and scientists keep discovering new things about them, Menchetti says. ‘’Ant diversity, a big fraction, is not well known, even in terms of species, and even less in terms of behavior. So we are still missing a lot of pieces of this puzzle.”
While ants may seem like boring household nuisances, they have more secrets to reveal—some even stranger than fiction.
