Hypothesis & Theory ARTICLE

Front. Physiol., 22 March 2013 | http://dx.doi.org/10.3389/fphys.2013.00054

Plasticity of collective behavior in a nomadic early spring folivore

  • Department of Biology, Concordia University, Montréal, QC, Canada

Collective behavior in the forest tent caterpillar (Malacosoma disstria) meets the thermal constraints of being an early spring folivore, but introduces other constraints in food choice. These are minimized by state-dependent, inter-individual, and ontogenetic variations in responses to social cues. Forest tent caterpillars use pheromone trails and tactile communication among colony members to stay together during foraging. At the group level, these rules lead to cohesive synchronized collective nomadic foraging, in which the colony travels en masse between feeding and resting sites. This paper proposes that synchronized collective locomotion prevents individuals from becoming separated from the colony and hence permits them to reap the advantages of group-living, notably collective basking to increase their body temperature above ambient and collective defense against natural enemies. However, this cohesive behavior also implies conservative foraging, and colonies can become trapped on poor food sources. High fidelity to pheromone trails leads to strong amplification of an initial choice, such that colonies seldom abandon the first food source contacted, even if a better one is nearby. The risk of this trapping is modulated both by consistent inter-individual variations in exploratory behavior and by inner state. Colonies consisting of active-phenotype or protein-deprived individuals that explore more-off trails exhibit greater collective flexibility in foraging. An ontogenetic shift toward more independent movement occurs as caterpillars grow. This leads to colony break-up as the season advances. Selection pressures facing older caterpillars favor solitary living more than in the earlier instars. Caterpillars respond to this predictably changing environment by altering their behavioral rules as they grow.

Keywords: Malacosoma disstria, foraging, thermoregulation, Lepidoptera, decision-making, group-living, social behavior

Citation: Despland E (2013) Plasticity of collective behavior in a nomadic early spring folivore. Front. Physiol. 4:54. doi: 10.3389/fphys.2013.00054

Received: 12 November 2012; Accepted: 06 March 2013;
Published online: 22 March 2013.

Edited by:

Audrey Dussutour, Centre National de la Recherche Scientifique, France

Reviewed by:

Swidbert R. Ott, University of Cambridge, UK
Ralf Heinrich, University of Göttingen, Germany

Copyright © 2013 Despland. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.

*Correspondence: Emma Despland, Department of Biology, Concordia University, 7141 Sherbrooke West, Montréal, QC H4B 1R6, Canada. e-mail: emma.despland@concordia.ca