Exploring termite’s behavior at a tunnel intersection: directional selection and the intersection passing time

Subterranean termites build complex tunnel networks for foraging below the ground. While traveling in the tunnels, termites are likely to encounter the tunnel intersections. Termite¢s behavior at the intersection is one of important factors to affect the foraging efficiency. In the present study, the behavior was systematically analyzed in the viewpoint of the directional selection and the spent time, t, for a termite to pass the intersection. To do so, we made two tunnels intersected with each other at a 90° angle in two-dimensional arena filled with moistened soil. The tunnels have varying widths (W₁ and W₂; 2, 3, or 4 mm). W₁ represents the width of the tunnel in which the termites advanced and W₂ represents the width of the other tunnel which the advancing termites encounter. For (W₁, W₂)=(2,2), (4,4), termites equally chose the three directions left, straight, and right, while for (W₁, W₂)=(3,3), termites chose straight preferentially. On the other hand, for (W₁, W₂)=(2,3), (2,4), and (3,4), termites advancing from the narrow tunnels tended to turn left or right, while termites advancing from the wide tunnel tended to go straight. For (W₁, W₂)=(2,2), (3,3), (2,3), (2,4), and (4,3), the passing time, t, was almost same regardless of direction. For (W₁, W₂)=(4,4), (3,2), t was shorter in advancing straight direction than in turning left or right. While, for (W₁, W₂)=(3,4), t was longer in advancing straight direction than left or right direction. In addition, we briefly discussed the behavioral strategy to increase the foraging efficiency in relation to the experimental results.