This pattern suggests that there may be limitations on the performance of PADT and FT jumping mechanisms based on size. In the 10–40 mg size range dominated by Auchenorrhyncha, there are only a few fast-jumping Orthoptera, such as the pygmy mole cricket Xya capensis ( Burrows and Picker, 2010). The recoil-driven jumps of insects are thus a subset of ‘latch-mediated spring-actuated’ behaviours, which are not directly actuated by muscle contraction, but instead by the quick recoil of an elastic energy store ( Ilton et al., 2018 Longo et al., 2019).Īll the species in the Auchenorrhyncha that have been shown to be capable of jumping with take-off velocities of more than 3 m s −1 have been small (most 100 mg), such as grasshoppers and locusts, but these all belong to the Orthoptera (Caelifera) and use a jumping mechanism based on the storage of energy in, and rapid extension of, the hind femoro-tibial joint (FT mechanism) ( Fig. 1B). Sudden recoil of these energy stores releases the stored energy and powers the rapid movements of the legs, accelerating the body more quickly and with greater power than could be delivered by the direct action of muscle alone. This is achieved by slow muscle contractions distorting mechanical specializations of the cuticular exoskeleton, which act as elastic energy stores, whilst the propulsive legs do not move. In small jumping insects, therefore, catapult mechanisms are used, which decouple muscle contractions from the eventual rapid movement ( Bennet-Clark, 1975 Burrows, 2003 Sutton et al., 2019). Muscles generate the most mechanical energy when they contract slowly ( Zajac, 1989), and this poses a problem for small animals that must produce rapid forceful movements, such as those needed for jumping, as they cannot exploit the leverage provided by long legs and have only a short time available for acceleration before the legs are completely extended. These large lantern bugs are near isometrically scaled-up versions of their smaller relatives, still achieve comparable, if not higher, take-off velocities, and outperform other large jumping insects such as grasshoppers. Such a jumping performance therefore required a power amplification mechanism with energy storage in advance of the movement, as in their smaller relatives. The required power output of the thoracic jumping muscles was 21,000 W kg −1, 40 times greater than the maximum active contractile limit of muscle. During these jumps, adults experienced an acceleration of 77 g, required an energy expenditure of 4800 μJ and a power output of 900 mW, and exerted a force of 400 mN. It took 5–6 ms to accelerate to take-off velocities reaching 4.65 m s −1 in the best jumps by female Kalidasa lanata. The hind legs were 20–40% longer than the front legs, which was attributable to longer tibiae. The kinematics showed that jumps were propelled by rapid and synchronous movements of both hind legs, with their trochantera moving first. Does a similar mechanism also propel jumping in these much larger insects? The jumping performance of two species of lantern bugs (Hemiptera, Auchenorrhyncha, family Fulgoridae) from India and Malaysia was therefore analysed from high-speed videos. They are up to 600 times heavier than smaller hemipterans that jump powerfully using catapult mechanisms to store energy. Lantern bugs are amongst the largest of the jumping hemipteran bugs, with body lengths reaching 44 mm and masses reaching 0.7 g.
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