Head-capsule design and mandible control in beetle larvae: A three-dimensional approach

This work provides the morphological basis of mandible kinematics of beetle larvae with different types of head capsules, orientation of mouthparts, m andible design, and feeding behavior. Short descriptions are provided for t he hypognathous head of Liocola marmorata (Scarabaeidae), the prognathous h ead of Cybister lateralimarginalis (Dytiscidae), and the hyperprognathous h ead of Hydrophilus piceus (Hydrophilidae). Using 3D measurements of a set o f points selected on the head, 3D models of head capsules and mandible arti culations were made for the larvae of these three species. Further calculat ions of the models showed differences in spatial positions of mandible axes and insertion points of mandible muscles. Functional consequences of these differences and evolutionary aspects of changes in head design and mandibl e articulations are discussed. It is suggested that the approach used in th is study may be useful for further comparative studies of mandible mechanic s of a broad variety of insect taxa. (C) 2000 Wiley-Liss, Inc.