Directional change in tunneling of subterranean termites (Isoptera: Rhinotermitidae) in response to decayed wood attractants.
Wood discs decayed with brown rot fungi and polymer discs impregnated with acetone extract of decayed wood were embedded in sand of a two-dimensional foraging arena to evaluate their attractant potential in directing termite tunnels toward them. Termites were released near one arena corner and were guided to follow the physical guideline of the arena edges. In the absence of the attractants, termites generally formed a relatively linear tunnel along the edges. When decayed wood discs or treated polymer discs were placed in wet sand near one side of the arena, termite tunnels departed from the arena edges and were oriented toward them. The attraction distance ranged from 12 to 18 cm. The attractant properties were most likely water soluble and permeated through wet sand to cause termites to change their orientation. The results demonstrated that when such attractants are placed near a bait station in the field, they may be used to direct termite foraging toward the station.
Tunneling activity of subterranean termites (Isoptera: Rhinotermitidae) in sand with moisture gradients.
Tunnel formation by Coptotermes formosanus and Reticulitermes flavipes was studied in a two-dimensional foraging arena with a moisture gradient. Moisture did not appear to affect tunneling when termite first emerged from the central release chamber. But as termites of both species moved further away from the chamber and into a moisture gradient, they tunneled significantly (P < 0.05) more in sand with a higher moisture content than in sand with a lower moisture content. Over the 10 d test period, both termite species tunneled more in sand with a higher moisture content. Fractal analysis indicated that regardless of the sand moisture content, termite tunnel geometry had a fractal dimension and termites generally tunneled more in higher moisture sand.
Trail and Territorial Communication in Social Insects
The social properties of insect colonies are sometimes described in seemingly contradictory terms. As pinnacles of biological complexity they are superorganisms and their emergent, colony-level characteristics are often referred to in terms of their elaborate and sophisticated nature. Yet the mechanisms that mediate social interactions and group phenomena, after empirical or theoretical analysis, are simple and parsimonious. This complexity-mediated-by-simplicity paradigm provides a heuristic approach to the analysis of the basic behavioral characteristics of the individual members of an insect society and the regulatory mechanisms of cooperative response, which are the fundamental elements from which colony-level behavior is derived. Inevitably, the dissection and reconstruction of insect social organization involves semiochemicals, because the principal sensory modality of integration, social coordination, and assembly of colony-level patterns is olfaction.