Rounding a corner of a bent termite tunnel and tunnel traffic efficiency.

Subterranean termites construct underground tunnels, tens to hundreds of feet, to reach feeding sites and to transport food items to their nest. To ensure a high rate food return to the nest, an optimized tunnel should be constructed. We found that termites (Coptotermes formosanus Shiraki) fill the corner of a bent tunnel with soil particles excavated from tunnel tip where their digging behavior is activated. The corner-filling behavior, eventually, made a sharp corner smooth-rounded. In the present study, we showed that the corner-filling behavior could play an important role in improving the tunnel traffic efficiency. To do this, we compared the termites' time spent for passing corners between with a right-angled flat tip (RA-corner), corresponding to the sharp corner, and with a rounded tip (R-corner) corresponding to the smooth-rounded corner. As a result, the passing time in the R-corner was significantly shorter than in the RA-corner. In addition, tunnel width effect was discussed in terms of individual movement.