The two groups of sensilla in the ventral coxal hairplate of Carausius morosus have different roles during walking

Abstract

Abstract. The ventral coxal hairplate (cxHPv) of the stick insect Carausius morosus Br. (Phasmida: Bacteriidae) contains two morphologically distinct groups of sensilla designated as group 1 and 2 (Gl, G2). The function of these sensilla during walking was tested by selectively ablating one or both groups on one middle leg in thirty‐four animals. It has previously been shown that ablation of the entire hairplate leads to two kinds of errors: the operated leg swings farther forward and the adjacent caudal leg ends its swing more to the rear relative to the operated leg. Following selective ablation of cxHPv Gl on the middle leg, the first kind of error is more pronounced, indicating that this group contributes more to limiting forward protraction during the swing. Following ablation of cxHPv G2, the second kind of error is more evident, indicating that during stance this group contributes more to the target information influencing the swing end‐point of the adjacent caudal leg. These results are interpreted to reflect the phasic and phasic‐tonic response characteristics of Gl and G2 hairs, respectively.