Chemical Integration of Myrmecophilous Guests inAphaenogasterAnt Nests

Alain Lenoir,Camille Ruel,Quentin Chalon,Tomáš Lackner,Ana Carvajal,Raphaël Boulay,Ángel Barroso

doi:10.1155/2012/840860

Abstract

Social insect nests provide a safe and favourable shelter to many guests and parasites. InAphaenogaster senilisnests many guests are tolerated. Among them we studied the chemical integration of two myrmecophile beetles,Sternocoelis hispanus(Coleoptera: Histeridae) andChitosa nigrita(Coleoptera: Staphylinidae), and a silverfish. Silverfishes bear low quantities of the host hydrocarbons (chemical insignificance), acquired probably passively, and they do not match the colony odour. Both beetle species use chemical mimicry to be accepted; they have the same specific cuticular hydrocarbon profile as their host. They also match the ant colony odour, but they keep some specificity and can be recognised by the ants as a different element.Sternocoelisare always adopted in other conspecific colonies ofA. seniliswith different delays. They are adopted in the twin speciesA. ibericabut never inA. simonelliiorA. subterranea. They are readopted easily into their mother colony after an isolation of different durations until one month. After isolation they keep their hydrocarbons quantity, showing that they are able to synthesize them. Nevertheless, their profile diverges from the host colony, indicating that they adjust it in contact with the hosts. This had never been demonstrated before in myrmecophile beetles. We suggest that the chemical mimicry ofSternocoelisis the result of a coevolution withA. seniliswith a possible cleaning symbiosis.

Highlights

Ant colonies often host microcosms of myrmecophile guests, mostly arthropods that take advantage of ant nest favourable environment and food resources [1,2,3]
The three guest species mimic chemically their host: they have the same hydrocarbons. This explains why they are tolerated inside the nest without being aggressed the ants and they have the host colony odour
This was predictable for Sternocoelis, which lives intimately with brood in the colony, but it was more surprising for Chitosa which has very few interactions with the host workers. Both species maintain some chemical specificity into the host colony (Figure 5), they are probably recognised as a different though tolerated element

Summary

Introduction

Ant colonies often host microcosms of myrmecophile guests, mostly arthropods that take advantage of ant nest favourable environment and food resources [1,2,3]. Chemical mimicry is achieved either in a few cases by biosynthesising the same hydrocarbons as their host (but this is rare) or more generally by acquiring them through cuticular contacts and/or grooming (e.g., the guest actively licks the host’s cuticle; see reviews by [9,10,11]). Callow ants are chemically insignificant which allows them to get accepted in alien colonies during the first hours after emergence (see [12]). Another possibility of integration has been discovered recently in social insects: guests and parasites can be chemically “transparent” if they have only saturated hydrocarbons, which are not involved

Methods

Results

Conclusion