Exocrine gland involvement in trailing behaviour in the Argentine ant (Formicidae: Dolichoderinae)

Abstract

Experimental trails run off natural field trails of Iridomyrmex humilis have been used to demonstrate the range of exocrine glands involved in trailing behaviour. Complex trailing reactions were recorded by high-speed movie photography, and their interactions were assessed by multivariate analysis. Pavan's gland is confirmed as the source of major trailing pheromone(s) deposited on the substrate, which act as strong, persistent attractants and activators. The mandibular glands produce volatile, transient behavioural signals in air; the anals produce anti-trailants; and the pharyngeals and venoms may possibly be implicated as the producers of trailing synergists. The findings for I. humilis are considered in relation to the evolution of trailing behaviour through the Formicidae.