Locomotion and attachment of leaf beetle larvaeGastrophysa viridula(Coleoptera, Chrysomelidae)

Abstract

While adult green dock leaf beetles Gastrophysa viridula use tarsal adhesive setae to attach to and walk on smooth vertical surfaces and ceilings, larvae apply different devices for similar purposes: pretarsal adhesive pads on thoracic legs and a retractable pygopod at the 10th abdominal segment. Both are soft smooth structures and capable of wet adhesion. We studied attachment ability of different larval instars, considering the relationship between body weight and real contact area between attachment devices and the substrate. Larval gait patterns were analysed using high-speed video recordings. Instead of the tripod gait of adults, larvae walked by swinging contralateral legs simultaneously while adhering by the pygopod. Attachment ability of larval instars was measured by centrifugation on a spinning drum, revealing that attachment force decreases relative to weight. Contributions of different attachment devices to total attachment ability were investigated by selective disabling of organs by covering them with melted wax. Despite their smaller overall contact area, tarsal pads contributed to a larger extent to total attachment ability, probably because of their distributed spacing. Furthermore, we observed different behaviour in adults and larvae when centrifuged: while adults gradually slipped outward on the centrifuge drum surface, larvae stayed at the initial position until sudden detachment.

A comparison of tarsal morphology and traction force in the two burying beetles Nicrophorus nepalensis and Nicrophorus vespilloides (Coleoptera, Silphidae)

“…In most of our experiments, both Nicrophorus species showed higher traction forces (although not always significant) on hydrophilic surfaces. Similar results with better attachment on hydrophilic surfaces (but not consistent for all comparisons) have been observed in the sawfly larvae of Rhadinoceraea micans [39] and in adult leaf beetles of Gastrophysa viridula [40]. Moreover, if present, the absolute differences between the different polarities in our experiments were small and depended, for the smooth and micro-rough surface, on the claw treatment.…”

Tardigrades exhibit robust inter-limb coordination across walking speeds

“…Most soft animals are legless (e.g., nematodes or the larval stages of insects like Drosophila ), and the lack of discrete contact points with the substrate makes it difficult to identify changes in the timing of ground interactions [32]. Deeper evaluation in Onychophorans (velvet worms) [23], and in the larval stages of holometabolous insect orders which have developed leg-like appendages called ‘prolegs’ on their abdomens (e.g., beetles [38]; sawflies, moths and butterflies [15, 31, 21]), has indicated that soft-bodied locomotion is less regular than that observed in jointed arthropods. It is unclear if this increased variability is due to differences in underlying neural connectivity, or is simply a consequence of increased degrees of freedom associated with controlling lobopodal locomotion.…”

Building Magnetoresponsive Composite Elastomers for Bionic Locomotion Applications

“…In nature, varieties of living creatures morphing motion modalities flourish, the crawling and rolling of caterpillars [88] , the anchor telescoping motion of inchworms [89] , the upward swimming of jellyfishes [90] , the undulatory topographical motion of batoidea [91] , the leaping of nematodes [92] , so forth [93][94][95] . These instances have stimulated scientists to build advanced actuators which can not only dynamically change their morphologies, but also motion at diverse environments when exposed to a stimulus.…”