Young ants of the species Cardiocondyla thoracica are born with a price on their head, as adult males instantly mark them for execution by gangs of murderous worker ants. Though ants of other related species have previously been observed taking out hits on rival adult males, this is the first time that researchers have seen this type of behavior directed towards infants.
This incredible discovery was made by researchers from the University of Regensburg and the Senckenberg Museum in Germany, who collected 10 colonies from Australia for observation in a laboratory. The fact that each colony only had one adult male led them to question how these alpha ants manage to rise to prominence and outcompete all other males of their generation for the right to their queen’s chamber.
To investigate, the researchers first placed males into colonies that were not their own, thus bringing them into contact with another adult male. Writing in the journal Entomological Science, the study authors note that, surprisingly, these rival males paid little attention to each other, and did not engage in combat. Yet, mysteriously, the mangled remains of dead infant ants kept appearing, suggesting that these youngsters were somehow being slaughtered.
When paying closer attention to the ants, the team discovered that as soon as any young male emerged from its pupa, the adult male of that colony would grab it in its mandibles and smear it with a “hindgut secretion”, consisting of intestinal fluids and poop. This then caused worker ants to brutally attack these besmeared youngsters, tearing them to pieces.
While recruiting contract killers to take out entire generations of ants as soon as they are born may seem like a pretty good way to fast track your way to extinction, this type of behavior does actually have a rather twisted logic to it. Unlike males from other ant species that breed with queens from nearby colonies, Cardiocondyla thoracica males reproduce only with their own queens. As such, they compete directly with every other male in their colony, so wiping out your adversaries before they have a chance to grow up and dethrone you is actually a pretty smart way to maintain your dominance.
Unfortunately for the adult males, however, this evil technique is not always successful, as the researchers did observe one case in which a young male was not attacked by worker ants, despite having been smeared and therefore marked for termination. As a result of this, the youngster was later able to mark the adult male with its own secretion, causing the workers to turn on their former master and dismember the ant whose malicious bidding they once served.
Image: An adult male besmears a freshly emerging male with its hindgut secretion, marking it for execution by worker ants. Heinze et al, Entomological Science
[H/T: New Scientist]
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