SCOTT SIMON, HOST:
The scientist E.O. Wilson once wrote that ants are the most warlike of all animals. He said clashes between ant colonies could make great military clashes seem almost small by comparison. Sometimes, instead of mass combat, ant colonies get conquered by stealth and deceit. NPR's Nell Greenfieldboyce reports on how an ant colony can be tricked into betraying its queen.
NELL GREENFIELDBOYCE, BYLINE: For an ant colony, the queen is a big deal. She lays all the eggs. The workers protect her and raise the young. After a colony has been around a while and gotten bigger, some of the offspring will be females that are capable of reproduction. These females fly away and try to establish new colonies. Erik Frank is an ant expert at the University of Wurzburg in Germany. He says the founding of a new colony is a precarious, fragile time. The would-be queen faces a lot of danger as she's out there on her own, laying the eggs that will produce her first workers.
ERIK FRANK: Even one small mistake or one bad-luck event that kills off your workforce can mean the end of the colony.
GREENFIELDBOYCE: So the females of some ant species avoid this risk by doing something tricky. They simply find an established colony - one that belongs to another queen. They kill off that queen and take her place so they can enjoy the protection and care of all of her workers.
KEIZO TAKASUKA: It is very efficient.
GREENFIELDBOYCE: Keizo Takasuka is a researcher at Kyushu University. He and some colleagues in Japan recently saw some female ants using a particularly devious method of defeating a reigning queen, which they describe in the journal Current Biology. First, he says, the female ant had to acquire some camouflage.
TAKASUKA: So she could invade into the colony.
GREENFIELDBOYCE: Since ants mainly tell friend from foe using chemical signals, the researchers let the female ant have contact with some worker ants from a colony so she could get exposed to their scent. After obtaining that, she was able to creep undetected through the colony, right up to the queen. Then the female ant shot jets of fluid from her abdomen, dousing the queen in some kind of chemical before retreating to a short distance away. Takasuka says they haven't identified the chemical yet, but...
TAKASUKA: It's my guess it is formic acid.
GREENFIELDBOYCE: That's used by some ants to signal danger. Whatever it was, putting this chemical onto the colony's queen had a dramatic effect. Swarms of workers who had been lovingly obedient, ready to protect her with their very lives, abruptly turned on her. They violently attacked her until she was dead. Erik Frank, the ant researcher in Germany, wasn't part of the research team, but he watched a video of the intruder's chemical spray and the colony's subsequent betrayal.
FRANK: Obviously there's absolutely zero benefit for the host colony to kill their own queen.
GREENFIELDBOYCE: The only benefits went to the invader - the female ant that was now able to assume the throne.
FRANK: I'm not surprised that the behavior occurs, but it was very cool to see.
GREENFIELDBOYCE: He says usually this kind of royal ant drama happens underground in the dark, which is why ants rely so much on chemical signals and why they're vulnerable to this kind of trickery.
Nell Greenfieldboyce, NPR News.
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