Jumping and kicking in bush crickets

Abstract

SUMMARYBush crickets have long, thin hind legs but jump and kick rapidly. The mechanisms underlying these fast movements were analysed by correlating the activity of femoral muscles in a hind leg with the movements of the legs and body captured in high-speed images.A female Pholidoptera griseoaptera weighing 600 mg can jump a horizontal distance of 300 mm from a takeoff angle of 34° and at a velocity of 2.1 m s-1, gaining 1350μJ of kinetic energy. The body is accelerated at up to 114 m s-2, and the tibiae of the hind legs extend fully within 30 ms at maximal rotational velocities of 13 500 deg. s-1. Such performance requires a minimal power output of 40 mW. Ruddering movements of the hind legs may contribute to the stability of the body once the insect is airborne. During kicking, a hind tibia is extended completely within 10 ms with rotational velocities three times higher at 41 800 deg. s-1.Before a kick, high-speed images show no distortions of the hind femoro-tibial joints or of the small semi-lunar groove in the distal femur. Both kicks and jumps can be generated without full flexion of the hind tibiae. Some kicks involve a brief, 40-90 ms, period of co-contraction between the extensor and flexor tibiae muscles, but others can be generated by contraction of the extensor without a preceding co-contraction with the flexor. In the latter kicks, the initial flexion of the tibia is generated by a burst of flexor spikes, which then stop before spikes occur in the fast extensor tibiae(FETi) motor neuron. The rapid extension of the tibia can follow directly upon these spikes or can be delayed by as long as 40 ms. The velocity of tibial movement is positively correlated with the number of FETi spikes.The hind legs are 1.5 times longer than the body and more than four times longer than the front legs. The mechanical advantage of the hind leg flexor muscle over the extensor is greater at flexed joint angles and is enhanced by a pad of tissue on its tendon that slides over a protuberance in the ventral wall of the distal femur. The balance of forces in the extensor and flexor muscles, coupled with their changing lever ratio at different joint positions,appears to determine the point of tibial release and to enable rapid movements without an obligatory co-contraction of the two muscles.

Jumping mechanisms and performance in beetles. I. Flea beetles (Coleoptera: Chrysomelidae: Alticini)

“…The slow muscle contraction performs a mechanical reversible deformation of the spring, energy is stored in the form of elastic strain energy and finally very rapidly converted into kinetic energy. The morphological structures for the accumulation and storage of the elastic energy in jumping insects are variable, taking the form of semilunar plates in grasshoppers, locusts and crickets (Burrows and Sutton, 2012;Burrows and Morris, 2003), resilin pads in fleas (Sutton and Burrows, 2011), thoracic pleural arches in froghoppers and planthoppers (Burrows, 2010), and an abdominal appendage in springtails (Brackenbury and Hunt, 1993). Some jumpers employ a 'locking mechanism' working as passive or active latches (e.g.…”

The green leafhopper,Cicadella viridis(Hemiptera, Auchenorrhyncha, Cicadellidae), jumps with near-constant acceleration

“…To date, jumping locomotion has been studied to understand kinematics, neural mechanisms, energy cost and scale effects (Alexander, 1995;Biewener and Blickhan, 1988;Scholz et al, 2006), but also to extract bio-mimetic principles to develop robotic platforms, which could use these mechanisms to move in unstructured and uneven terrains (Cham et al, 2004;Scarfogliero et al, 2009). The jumping strategy of insects has been studied by means of high-speed video recordings and anatomical or physiological observations (Bennet-Clark and Lucey, 1967;Brackenbury and Wang, 1995;Burrows and Morris, 2003;Burrows, 2006). Nowadays, a great number of features have been identified, such as average take-off velocity, average thrust, leg morphology and kinematics, and the mechanisms for storing and releasing muscular energy (Gronenberg, 1996;Burrows, 2003).…”

Allometry and ontogeny in Callibia diana Stål (Mantodea: Acanthopidae)

“…Many groups of insects possess energy storage mechanisms such as the well-known semi-lunar hind leg process of the Orthoptera (Burrows & Morris 2003). This mechanism allows them to generate more ef icient speed movements, thereby optimising muscle requirements.…”