Honesty of Larval Begging Signals Covaries With Colony Kin Structure in Formica Ants

Mélissa Peignier,Eva Schultner,Heikki Helanterä,Rosanna Lindgren,Jürgen Heinze,Tamara Pokorny

doi:10.3389/fevo.2019.00398

Abstract

Social insects live in highly complex societies with efficient communication systems. Begging is one display commonly used by offspring to signal their nutritional state, however begging behavior has received very little attention in social insects. Theory predicts that begging can be either an honest (i.e. honest-signaling strategy) or a dishonest (i.e. scrambling competition) signal of need, with dishonest signals expected to be more likely when relatedness within the group is low. To investigate the presence and honesty of begging, as well as the nature of the involved signals, we used a comparative approach with four species of the ant genus Formica known to differ in the degree of intra-colony relatedness. We investigated the behavior of starved and non-starved larvae of F. aquilonia, F. pressilabris (both low intra-colony relatedness), F. exsecta (intermediate relatedness), and F. fusca (high relatedness). In addition, we assessed the attraction of conspecific workers towards odors extracted from these two classes of larvae and analyzed the larval cuticular hydrocarbon profiles. We found that in F. fusca and F. exsecta, larvae signaled significantly more when starved. In contrast, larvae of F. aquilonia signaled significantly more when they were non-starved, while there was no significant difference in the behavior of starved versus non-starved larvae in F. pressilabris. Our results show that workers were not preferentially attracted to the odor of starved larvae, and we also did not detect any differences between the cuticular hydrocarbon profiles of starved and non-starved larvae. Overall, this study demonstrates among species variation in larval hunger signaling in Formica ants, and encourage further studies for confirming the link between kin structure variation and the honesty of begging signals.

Highlights

Communication systems allow individuals to base their adaptive decisions on the behavior, morphology, or physiology of others (Endler, 1993)
We focused on Formica ants because their colony kin structures range from single queen colonies with high intracolony relatedness to multiple queen colonies with extremely low relatedness among nestmates (Rosengren et al, 1993; Sundström et al, 2005)
In line with inclusive fitness predictions, we find that starved larvae signaled significantly more than non-starved larvae in Formica fusca and F. exsecta, i.e., species with high and intermediate levels of intracolony relatedness

Summary

Introduction

Communication systems allow individuals to base their adaptive decisions on the behavior, morphology, or physiology of others (Endler, 1993). When the inclusive fitness interests of the sender and the receiver diverge, the ultimate aim of the sender is not the sharing of mutual beneficial information, and conflicts over information use arise (Owren and Rendall, 1997, 2001; Seyfarth and Cheney, 2003). In such cases, selection should favor senders, whose signals affect the behavior of the receiver at their own advantage, and receivers, who are able to extract information from the signals (Endler, 1993; Font and Carazo, 2010). Related individuals should be more likely to communicate honestly in order to cooperate, whereas the opposite would be expected for non-relatives

Objectives

Methods

Results

Conclusion