Chemical strategies to deal with ants: a review of mimicry, camouflage, propaganda, and phytomimesis by ants (Hymenoptera: Formicidae) and other arthropods

Abstract

Chemical tactics by ant social parasites, including myrmecophiles, often relate to ant nestmate recognition and alarm communication. The strict nestmate recognition system in ants can be disrupted by chemical imitation of the nestmate recognition pheromone, which consists of cuticular hydrocarbon components. Social parasites often acquire these components through direct body contact, but occasionally synthesize them even before ant adoption. Such an imitation of the host cuticular chemicals causes species-specific adoption of the parasites, which are then often taken care of by ants for long terms. In contrast, transient invaders often use a propaganda allomone that induces panic alarm responses in ants. The allomone occasionally even causes fighting among nestmate ants, and seems to disrupt the ant nestmate recognition. These two chemical strategies are to modify the ant responses after ant detection. A third chemical strategy taken by some insect species is to avoid the detection itself, and is evidenced in the chemical phytomimesis by geometriid twiglike caterpillars. Since this counts upon the ants not to respond to the invasion, it usually does not cause visible responses when it works effectively. Appropriate evaluation methods are necessary to evaluate the ant responses induced by the parasites to reveal the underlying mimetic strategy.