Structures, properties, and energy-storage mechanisms of the semi-lunar process cuticles in locusts

Abstract

Locusts have excellent jumping and kicking abilities to survive in nature, which are achieved through the energy storage and release processes occurring in cuticles, especially in the semi-lunar processes (SLP) at the femorotibial joints. As yet, however, the strain energy-storage mechanisms of the SLP cuticles remain unclear. To decode this mystery, we investigated the microstructure, material composition, and mechanical properties of the SLP cuticle and its remarkable strain energy-storage mechanisms for jumping and kicking. It is found that the SLP cuticle of adult Locusta migratoria manilensis consists of five main parts that exhibit different microstructural features, material compositions, mechanical properties, and biological functions in storing strain energy. The mechanical properties of these five components are all transversely isotropic and strongly depend on their water contents. Finite element simulations indicate that the two parts of the core region of the SLP cuticle likely make significant contributions to its outstanding strain energy-storage ability. This work deepens our understanding of the locomotion behaviors and superior energy-storage mechanisms of insects such as locusts and is helpful for the design and fabrication of strain energy-storage devices.

Material composition of the mouthpart cuticle in a damselfly larva (Insecta: Odonata) and its biomechanical significance

“…Using CLSM for assessing the material composition, as in this study, allows for the detection of areas with different material properties and for a detailed understanding of the material distribution [ 3 , 11 , 18 ]; this knowledge can be transferred to computer models used in FEM [ 16 , 51 ]. Although CLSM does not allow for a precise measurement of the properties of the identified materials, the information on the material distribution can be used as a template for targeted nanoindentation or atomic force microscopy (AFM) [ 3 , 46 ], which in turn can be employed to refine finite-element or other models.…”

The Effect of Ground Type on the Jump Performance of Adults of the Locust Locusta migratoria manilensis: A Preliminary Study

“…Given that the main purpose of jumping for adult locusts is to achieve a sufficient initial speed for initiating flight [17], the fact that the take-off speed did not change among the different ground types revealed that the jump behaviors of the locust were robust on various substrates. The kinetic energy of the locust jump was primarily released from the elastic strain energy stored by the SLP cuticle during the extension of the hind leg [3,4]. The similar mass-specific kinetic energy for the jumps on the three ground types meant that the stored strain energy was not wasted by the somewhat useless extension arising from the slip or insertion of tibia.…”

“…Their jumps serve several critical functions: to escape from predators, to achieve an initial velocity for flight, and provide a more rapid alternative to travel than crawling. The locust jump has been extensively studied, especially its postural control, the mechanics of the hind leg, patterns of muscle and motoneuron activity, and mechanisms of energy storage and release [2][3][4][5][6][7][8][9][10][11]. The action of jumping in locusts is fueled by their hind legs in the following steps: initial flexion of the tibiae, co-contraction of the flexor and extensor muscles, and rapid tibial extension after trigger activity [2].…”

“…The action of jumping in locusts is fueled by their hind legs in the following steps: initial flexion of the tibiae, co-contraction of the flexor and extensor muscles, and rapid tibial extension after trigger activity [2]. A large amount of strain energy is stored by the deformed exoskeleton during muscle co-contraction (especially by the semi-lunar process (SLP) cuticle on the distal end of the metathoracic femur) and is released during tibial extension to overcome the weaknesses of insect muscles [3,4].…”

Comparative proteomics reveals complex insecticides-associated resistance mechanism of Culex pipiens pallens Coquillett

“…The insect cuticle, also known as the exoskeleton, is the outermost part of the insect body, it serves a variety of functions such as sensory perception of the environment, means of locomotion [36], maintain the physical structure of the organism, the foregut, hindgut, tracheal system and apodemes [37], and protection from desiccation, moreover, the cuticle also serves as the rst and major barrier against external adverse compounds penetration [38]. So, the cuticle is a major route of insecticide penetration in insects, insect cuticles are composed of cuticular protein, chitin and lipids, in fact, the properties of insect cuticle including permeability to pyrethroids are in uenced not only by the chitin sclerotization, construction, and hydration, but also by the regular combinations of different cuticular proteins and their arrangements [38,39], recent protein-level and gene-level analyses have demonstrated a surprising diversity of cuticular proteins within and amongst species [40].…”