Dear Enemy Phenomenon in the Ant Ectatomma brunneum (Formicidae: Ectatomminae): Chemical Signals Mediate Intraspecific Agressive Interactions

Márlon César Pereira,Rafaella Caroline Bernardi,Ellen Liciane Barbosa Firmino,Claudia Andrea Lima Cardoso,William Fernando Antonialli Junior,Luan Dias Lima,Ingrid De Carvalho Guimarães

doi:10.13102/sociobiology.v66i2.3554

Abstract

The integrity of ant colonies depends exclusively on social relationships between their individuals, especially the ability of communication between group members, which is mainly mediated through chemical signals. Another important feature of ant behavior is territory defense, since they need to gather large amounts of food to feed their larvae, males and breeding females. Thereby, ants might display behavioral strategies to defend their territories from intruders. Here we investigated whether Ectatomma brunneum displays the Dear Enemy Phenomenon, what is the relationship between Cuticular Hydrocarbon composition and levels of aggression during their intraspecific interactions and which compounds and/or classes of compounds might be the most important to modulate the level of aggression. To test our hypothesis, we evaluated the levels of aggression through behavioral observations during interactions between 23 pairs of colonies nested in two distinct sites at varied distances. Then, we analyzed the cuticular chemical profile of the individuals involved in the interactions, and compared these results with the levels of aggression displayed between colonies tested. The results allow us to confirm our hypothesis that the DEP occurs in E. brunneum. The higher tolerance between closer colonies can be explained due to their kinship level in addition to sharing the same microhabitats. The results also showed there are significant differences in CHCs profiles, especially between colonies nested at relatively greater distances, and it is likely that differences in content of some branched alkanes are the most important to establish these differences and, therefore, the levels of aggression during the interactions.

Highlights

As in other insects’ societies, ants are characterized by a high degree of cooperation between different individuals in the colony
Social insects use mainly chemical signals for communication, especially the Cuticular Hydrocarbons (CHCs) which might vary between colonies or even between castes (e.g. Blomquist et al, 1998; Lenoir et al, 1999; Antonialli-Junior et al, 2007)
We investigated whether E. brunneum displays the Dear Enemy Phenomenon” (DEP), what is the relationship between the CHC and levels of aggression during their intraspecific interactions and which compounds and/or classes of compounds might be the most important to modulate the level of aggression

Summary

Introduction

As in other insects’ societies, ants are characterized by a high degree of cooperation between different individuals in the colony. The integrity of the colony depends exclusively on the social relationships between its individuals and their ability of communication between group members (Crozier & Pamilo, 1996). Social insects use mainly chemical signals for communication, especially the Cuticular Hydrocarbons (CHCs) which might vary between colonies or even between castes CHCs have profiles both genetically and environmentally determined (Sorvari et al, 2008), which are used by workers as “signatures” for intra and interspecific recognition (Arnold et al, 2000). The existence of these recognition mechanisms is of great value, especially in intraspecific interactions.

Methods

Results

Discussion

Conclusion