Division of Labor Regulates Precision Rescue Behavior in Sand-Dwelling Cataglyphis cursor Ants: To Give Is to Receive

Elise Nowbahari,Karen L. Hollis,Jean-Luc Durand,Georges Chapouthier

doi:10.1371/journal.pone.0048516

Abstract

Division of labor, an adaptation in which individuals specialize in performing tasks necessary to the colony, such as nest defense and foraging, is believed key to eusocial insects' remarkable ecological success. Here we report, for the first time, a completely novel specialization in a eusocial insect, namely the ability of Cataglyphis cursor ants to rescue a trapped nestmate using precisely targeted behavior. Labeled “precision rescue”, this behavior involves the ability of rescuers not only to detect what, exactly, holds the victim in place, but also to direct specific actions to this obstacle. Individual ants, sampled from each of C. cursor's three castes, namely foragers, nurses and inactives, were experimentally ensnared (the “victim”) and exposed to a caste-specific group of potential “rescuers.” The data reveal that foragers were able to administer, and obtain, the most help while members of the youngest, inactive caste not only failed to respond to victims, but also received virtually no help from potential rescuers, regardless of caste. Nurses performed intermediate levels of aid, mirroring their intermediate caste status. Our results demonstrate that division of labor, which controls foraging, defense and brood care in C. cursor, also regulates a newly discovered behavior in this species, namely a sophisticated form of rescue, a highly adaptive specialization that is finely tuned to a caste member's probability of becoming, or encountering, a victim in need of rescue.

Highlights

IntroductionOne of the most prominent and widely studied features of colony behavior in social insects [1,2,3,4,5,6], takes one of two general forms: morphological polyethism, in which workers’ size and/ or shape determines what tasks they will perform; and, temporal polyethism, in which individuals perform different tasks as they mature [1,2,3,4,5,6,7]
Division of labor, one of the most prominent and widely studied features of colony behavior in social insects [1,2,3,4,5,6], takes one of two general forms: morphological polyethism, in which workers’ size and/ or shape determines what tasks they will perform; and, temporal polyethism, in which individuals perform different tasks as they mature [1,2,3,4,5,6,7]
In the present study, we examined the role of polyethism in the rescue behavior of C. cursor ants by conducting tests of rescue behavior in which we systematically varied the caste of both victim and rescuers

Summary

Introduction

One of the most prominent and widely studied features of colony behavior in social insects [1,2,3,4,5,6], takes one of two general forms: morphological polyethism, in which workers’ size and/ or shape determines what tasks they will perform; and, temporal polyethism, in which individuals perform different tasks as they mature [1,2,3,4,5,6,7]. Temporal polyethism is widespread in social insects and typically follows the pattern of younger workers performing tasks within the nest and older workers performing tasks outside, such as foraging and defense [1,2,3,4,5,6,7]. This behavioral specialization, which is thought responsible for social insects’ enormous ecological success, increases the overall efficiency of the colony because workers that focus on and repeat a particular task will perform it more reliably [2], [6]. Aimed, biting at the obstacle never is misplaced, even though it may be in direct contact with the victim’s body

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Conclusion