Movement Efficiency and Behavior of Termites (Isoptera) in Tunnels with Varying Pore Sizes

Sook Junk Ku, Nan-Yao Su, Sang-Hee Lee

Abstract


Subterranean termites (Isoptera) build tunnel networks to obtain food resources and nesting space. When tunneling, termites encounter spatial heterogeneity, such as differing soil pore space and moisture levels. This heterogeneity creates 2 types of irregularities in the tunnel surface: (1) a bumpy tunnel-wall structure caused by variable soil texture; and (2) hollow space within the tunnel, where tunnels pass through soil pores. We previously explored the response of termites to bumpy tunnel structure. In the present study, we investigated termite behavior in response to differing volumes of soil pore space. This response behavior is closely related to movement efficiency. We designed 8-cm-long artificial tunnels with hollow spaces in a 2-dimensional arena. The hollow spaces were represented as circular holes with varying diameters D (2, 3, 4, 6, 8, or 10 mm), positioned at the center of the tunnel. Tunnel widths, W, were 2 and 3 mm. We systematically observed the movement of termites (Reticulitermes speratus kyushuensis Morimoto) at the hole, and measured the time required (τ) for termites to pass through the tunnels. Time τ was shorter for tunnels with holes between 2 and 6 mm diameter than for those with holes of 8 or 10 mm diameter, for tunnels of both widths. Time τ was significantly different between (W, D) = (2, 10) and (3, 10). These results were explained by 3 types of behaviors. The implications of these findings are briefly discussed in relation to termite foraging efficiency.

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