Hidden burrow plugs and their function in the tiger beetle, Cosmodela batesi (Coleoptera, Cicindelidae)

Abstract

Abstract Tiger beetle larvae excavate and live in underground burrows, whose openings they sometimes plug with soil. This study documents the burrow plugging behavior of the tiger beetle, Cosmodela batesi (Fleutiaux), in the field. We also tested the function of burrow plugs in the laboratory. In the field, C. batesi more frequently made a plug when it rained. Most larvae made plugs inside their burrows (rather than at the soil surface), and the use of an endoscope was necessary to detect these sub-surface plugs. In the laboratory, flooding was simulated by artificially introducing water into specially-made arenas. Water filled the entire burrow when there was no plug, whereas plugged burrows maintained air chambers inside. When a plug was broken with a wire, burrows filled up with water. The burrowing and plugging behavior described in this study is likely an important adaptation of C. batesi to its habitat.