Shelter tube geometry of the Asian subterranean termite in response to wood abundance across population size.

Some termite species can build shelter tubes while exploring in the open. Functionally, shelter tubes are critical structures that enable subterranean termites such as Coptotermes gestroi (Wasmann) to access human-built structures, yet the factors governing shelter tube geometry formation remain poorly understood. We investigated how colony population size and wood abundance affect shelter tube geometry (total length, branch frequency, and branching angle) and construction speed in C. gestroi. Nine colonies, varying in population size, were allowed to construct shelter tubes in an open-air arena across 3 levels of wood abundance (zero, 2, and 4 wood blocks). In this study, geometric components of shelter tubes and construction speed were not significantly affected by wood abundance. Termite scouting behavior may have been suppressed by the smooth arena substrate in the present study, potentially limiting exploratory behaviors for food sources. However, tunnel length and tunnel branching frequency were both positively impacted by termite colony size, which remains a key factor for aboveground gallery expansion capabilities in C. gestroi.