Some parasitic ants usurp colonies of related species by prompting worker ants to eliminate and replace the resident queen.

Approximately 230 species of ants are classified as parasitic, depositing eggs within the nests of other species or pilfering larvae and pupae. Certain species eliminate the host queen before laying their eggs and manipulate the worker ants to care for these eggs instead.

Professors Keizo Takasuka and his colleagues at Kyushu University in Fukuoka, Japan, observed this behavior when the queen of the parasitic species Lasius orientalis inadvertently invaded a relative’s nest, Lasius flavus. The workers proceeded to kill their own queen.

While many parasitic queens face elimination by worker ants upon discovery, some manage to camouflage themselves with the colony’s scent and evade detection.

To gauge the effectiveness of the parasitic queens, the researchers aided the intruders by disguising them with the scent of worker ants before placing them into the colony.

“It reminds me of the TV series The Walking Dead, where characters pass through hordes of zombies with walker blood smeared on them, operating under a disguise that often fails, leading to brutal deaths for those exposed,” Takasuga remarks.

Once the parasite breaches a colony, it emits a chemical, likely formic acid, through a gland at the end of its abdomen to target a rival queen.

Worker ants perceive this chemical as a threat and attack the rival queen upon detecting it. However, the process is gradual, necessitating multiple sprays and numerous assaults before the queen is ultimately killed. The parasitic queen can then lay her eggs, which are nurtured by the worker ants.

“If the parasitic strategy succeeds, the new queen can navigate the delicate establishment phase much more securely than if she were to start a colony independently,” Takasuga comments. “This approach might be more prevalent than we currently acknowledge.”

Researchers at Macquarie University in Sydney, Australia, including Chris Reid, assert that the intricate behaviors of ants are challenging to observe due to their subterranean nests.

“This form of natural history detective work is crucial for enhancing our understanding of these immensely significant insects,” Reid notes. “Further investigations may even pave the way for novel methods to target invasive ant queens, a major challenge facing ecosystems globally.”