Collective and Cooperative Foraging
Social caterpillars exhibit three basic foraging patterns. Patch-restricted foragers obtain all of the food required during the social phase of their larval development from the leaves found in a single contiguous patch or from several such closely spaced patches. The foraging arena is typically well defined by a protective silk envelope or by leaves bound together. On large trees, patches usually consist of the leaves found on a part of a branch, an entire branch, or on several closely situated branches. But on small trees and herbaceous plants the entire host may eventually be enveloped. Although there have been no surveys to determine the proportion of social caterpillars that exhibit each of these foraging patterns, patch-restricted foraging is probably the most common and also the least complex. Well known examples of patch restricted foragers include the Euonymus caterpillar, Yponomeuta cagnagella and the ugly nest caterpillar, Archips cerasivoranus. The fall webworm Hyphantria cunea, is a patch restricted forager during the initial stages of its development.
Nomadic foragers establish only temporary resting sites and make frequent moves from one patch to another. The forest tent caterpillar, Malacosoma disstria and the spiny elm caterpillar, Nymphalis antiopa are nomadic foragers.
Central-place foragers construct a permanent or semi-permanent shelter from which they launch intermittent forays to distant sites in search of food. Between bouts of feeding the caterpillars rest at the shelter. The best known of the social caterpillars that are central place foragers include the tent caterpillars other than M. disstria, and the processionary caterpillars of Europe (Thaumetopoea) and Australia (Ochrogaster).
The most sophisticated form of cooperative foraging exhibited by caterpillars is recruitment communication in which caterpillars recruit siblings to their trails and to their food-finds by marking pathways with pheromones much in the manner of ants and termites. The most sophisticated examples of recruitment communication have been described from the tent caterpillars (Malacosoma). Eastern tent caterpillars (M. americanum), for example, utilize a trail-based system of elective recruitment communication that enables the colonies to exploit the most profitable feeding sites.
Read more about this topic: Social Caterpillars
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