Physical and biological determinants of collective behavioural dynamics in complex systems: pulling chain formation in the nest-weaving ant Oecophylla smaragdina.

Thomas Bochynek,Simon K A Robson,Stephen C Pratt

doi:10.1371/journal.pone.0095112

Thomas Bochynek, Simon K A Robson + Show 1 more

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https://doi.org/10.1371/journal.pone.0095112

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Abstract

The evolution of nest weaving, the inclusion of larval silk in the nest walls, is considered one of the pinnacles of cooperative behaviour in social insects. Within the four ant genera in which this has evolved, Oecophylla are unique in being the only group that precedes the deposition of larval silk by actively manipulating the leaf substrate to form a nest chamber. Here we provide the first descriptions of the manipulation process within a complex-systems framework. Substrate manipulation involves individual ants selecting, grasping and attempting to pull the edge of the substrate. These individuals are then joined by nest mates at the work site, who either select a site beside the first individual or grasp the body of the first or preceding worker to form a chain of pulling ants that together drag and bend the substrate. Site selection by individual workers is not random when confronted with an artificial leaf, with individuals more likely to grasp a substrate at its tip rather than along a more broad edge. The activity of additional individuals is also not random, with their activity being grouped in both space and time. Additional individuals are more likely to join an existing biting individual or pulling group. The positive feedback associated with the early stages of pulling behaviour appears typical for many of the collective actions observed in social insects.

Highlights

Social insects are prime examples of collective systems in which numerous relatively simple individuals can together display highly diverse and adaptive group-level behaviours [1,2,3]
Numerous studies of social insects exploring these processes include the selection of new nest sites in Apis [4] and Temnothorax [5,6], the dynamics of foraging in army and mass recruiting ants [7,8], nest building in wasps [9] the regulation of nest temperature in Apis [10], retrieval group size in Formica schaufussi [11] and adaptive search in termites [12]
The importance of nest construction and self-assemblages to many social insect species suggest that studies of such processes, though relatively under explored, play a key role in understanding the dynamics of collective action [22]

Summary

Introduction

Social insects are prime examples of collective systems in which numerous relatively simple individuals can together display highly diverse and adaptive group-level behaviours [1,2,3]. Numerous studies of social insects exploring these processes include the selection of new nest sites in Apis [4] and Temnothorax [5,6], the dynamics of foraging in army and mass recruiting ants [7,8], nest building in wasps [9] the regulation of nest temperature in Apis [10], retrieval group size in Formica schaufussi [11] and adaptive search in termites [12]. The importance of nest construction and self-assemblages to many social insect species suggest that studies of such processes, though relatively under explored, play a key role in understanding the dynamics of collective action [22]

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