Meeting Abstract
Social insects, such as honeybees, ants and termites are excellent model systems to understand how organisms collectively self-organize to cooperatively carry out tasks relevant for their survival. Mound building termites are especially interesting in this regard because they build extraordinary structures to house their colony. Within these large structures is a maze of narrow passageways that they traverse in an efficient manner, a task that is especially challenging because these termites, barring their alate forms, lack image-forming eyes and live entirely underground where light does not penetrate. What sensory cues govern the traffic of termites under such conditions? To study this question, we developed a behavioral assay in which the termites (Odontotermes obesus) were placed in a circular arena with a confining sleeve and their behavior filmed using an overhead camera. We observed that such termites milled around the arena in a regular fashion, and this behavior was density-dependent. We proposed the hypothesis that milling results from physical processes such as those seen in bristlebots – vibrating robotic devices that self-organize through a passive mechanical process. An alternative hypothesis requires the presence of sensory cues to drive such behavior. To test these hypotheses, we removed the bounding sleeve of the arena, and observed that, once established, the milling persisted. Replacing these termites with a naïve set established milling in absence of the confining sleeve. However, replacing part of the arena floor with a fresh floor disrupted the behavior. These observations show that milling behavior is initially established by mechanical cues, but later sustained by the chemical trails laid down by the termites.
