A pocket watch is being swung right in front of your eyes. Your eyes track it, and a soothing voice asks you to “sleep”. A snap later, you lose your senses and become a puppet of the hypnotist. Movies portray it as a surreal experience; in reality, it’s far worse. And beneath our feet, an ant queen will meet her demise in the mandibles of worker ants, under the influence of a parasitic mind-controlling chemical attack from another.
The assassination can go toe-to-toe with Shakespearean drama. The queen of the colony dies in the hands of her “brainwashed” daughter ants, under the chemical influence of the invader queen, who sees her assassination scheme come to fruition. It’s a coup in which the nest is seized, as the colony’s ants mistake their queen for an imposter. The nest’s queen will eventually fall, and the invader queen will take over the crown.
Queens are often killed in a colony, usually when there are multiple queens produced in a single colony, or when a single queen reaches the end of her fertility. However, an invasion by a queen from a different colony, using the victim’s colony’s ants as her own soldiers, has not been well documented. In fact, there have been no other reports of this kind of infiltration in any other species that have a queen.
Dr. Keizo Takasuka, an assistant professor in the Department of Biology at the University of Kyushu in Japan, the senior author of the study, recorded this form of warfare in Lasius species, particularly L. orientalis and L. umbratus.
“Prior studies had reported that, after a new L. umbratus queen invaded a host colony of L. niger, host workers killed their own queen,” Takasuka said. “But the mechanism remained entirely unknown until our study.”
Ants use chemical signals to communicate and to distinguish nestmates from enemies. Parasitic ant queen catches up to a worker ant and rubs it on its body to mask its own scent and take on the worker’s chemical signature. They do this around the foraging trails of ants, and then slip into their nest right under their nose.
Co-authors of the study, Taku Shimada and Yuji Tanaka, both citizen scientists, raised an ant colony and released parasitic queens into it. Shimada worked with the L. orientalis queen in the L. flavus colony, while Tanaka recorded L. umbratus queen invading a L. japonicus colony. In both instances, the scientists housed the parasitic queen with host workers to ensure that the parasitic queen could acquire the nestmate odor before infiltrating and avoid detection upon entry. Then the queens were released into the colony.
The method of attack was similar in both cases. After picking up the worker’s scent, the queens entered the colonies’ feeding area. The workers didn’t find anything unusual with the imposter, with some even feeding them mouth-to-mouth.
The invading queen was not interested in food; she wanted to ensure that the host queen had “The Last Supper”. The parasitic queen locates the parasitic queen and sprays it with formic acid, which agitates the workers. These workers then turn on their queen in no time and attack her. Attacks become more and more brutal, as more formic acid is sprayed on them. In just four days, the host queen, their mother, gets mutilated.
With the death of the host queen, the invader starts producing hundreds of eggs, which the old queen’s daughters attend to. Eventually, the invader’s daughters will grow in number and overthrow the colony, leaving no ants of the former species alive.
Dr. Jessica Purcell, a professor in the department of entomology at the University of California, Riverside, sees this research as a refreshing take with minute observation. She is especially stunned at the fact that the attacking queen uses chemical compounds to seize power, using none of her own forces.
Social insects like ants gather and store resources for the colony to share, which makes them targets for social parasites. These parasites look for stacked nests to exploit them. Some kidnap host queens, while others eliminate existing queens.
Violence in families is a recurring theme in fairy tales and myths, such as Rapunzel being imprisoned, Snow White being hunted, and the poison plot, among others. Usually, it’s the parents who do so out of envy, but matricide is almost nonexistent. The invasion of the parasitic ant queen is thus an epitome of a grim tale that outdoes fiction. Truth is, indeed, stranger than fiction.
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