Parasitic ant tricks workers into killing their queen, then usurps her
The queen of parasitic ants Lasius orientalis (left) infiltrates the nest of Lasius flavus and approaches their queen (right)
Keizo Takasuka/Kyushu University
A type of parasitic ant takes over colonies of a related species by tricking workers into killing their queen and then taking her place.
About 230 species of ants are considered parasites: they lay their eggs in the colonies of other species or steal their larvae and pupae. Some kill host queens before laying their own eggs and convincing workers to serve them instead.
Keizo Takasuka of Kyushu University in Fukuoka, Japan, and colleagues noticed that when a queen of the parasitic species Lasius orientalis was accidentally introduced into the nest of its relative, Lasius flavusTHE flavus the workers then killed their own queen – their mother.
Many parasitic queens are killed by workers once discovered, but some pass through the colony’s defenses, apparently by hiding in the colony’s scent.
To observe how the parasitic queens succeeded, the researchers helped them by masking the intruding females with the scent of worker ants before introducing them to the colony.
“It’s reminiscent of the zombie TV series, The Walking Deadwhere characters smear themselves in walker blood to move through a horde – this involves camouflage which often fails, and those exposed are brutally killed,” explains Takasuka.
Once the parasite enters the colony, it sprays the rival queen with a chemical, believed to be formic acid, from a hole at the end of her abdomen.
Workers interpret this chemical as a danger to the colony and immediately attack their queen as soon as they smell it. However, the process is slow, requiring multiple sprays and numerous attacks from its workers before the queen is finally killed. The parasitic queen can then lay her own eggs, which are cared for by workers.
“If parasitism is successful, it allows the new queen to pass through the vulnerable founding phase much more safely than founding a colony alone,” says Takasuka. “I suspect this strategy may be more widespread than we currently imagine.”
Chris Reid of Macquarie University in Sydney, Australia, says the ants’ complex behaviors are difficult to observe because they occur in the privacy of the underground nest.
“This type of natural history detective work is essential to improving our understanding of these extremely important insects,” says Reid. “Further studies could even lead to new ways to target the queens of invasive ant species, which pose one of the biggest challenges facing ecosystems around the world.”
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