If you are a new slave-making ant queen, looking for a nest to enslave. How are you going to this? The problem is, ants can smell out almost any intruder, so getting into their fortress in order to take it over is not an easy task.
Queens of the Amazon ant found a solution for this. Or actually, two solutions! First of all, they try to reduce their smelliness, which makes it harder for her potential slaves to recognize and kill her. However, this doesn’t always work, and she might still get attacked. What’s the solution to this? Chemical weaponry!
Amazon ant queens produce a certain kind of chemical that’s extremely repulsive to the ants she wants to enslave. Once she gets attacked, she can use this to repel the attackers. While the attackers are being busy being disgusted, the slave-making ant queen can try to find the queen of the nest she’s trying to enslave. Once found, she can kill that queen and take over the nest. While being in contact with the queen she’s killing, she absorbs the smell of said queen as well, and suddenly the slaves will not recognize her as an enemy anymore, but as their own queen.
d’Ettorre et al. (2000). Sneak in or repel your enemy: Dufour’s gland repellent as a strategy for successful usurpation in the slave-maker Polyergus rufescens. Chemoecology: 10(135-142)