Jumping mechanisms in flatid planthoppers (Hemiptera, Flatidae).

The jumping performance of three species of hemipterans from Australia and Europe belonging to the family Flatidae was analysed from images captured at a rate of 5000 s(-1). The shape of a flatid was dominated by large triangular or wedge-shaped front wings, which, when folded, covered and extended above and behind the body to give a laterally compressed and possibly streamlined appearance. The body lengths of the three species of adults ranged from 7 to 9 mm and their mass from 8 to 19 mg. The propulsive hind legs were 30% longer than the front legs but only 36-54% of the body length. Jumps with the fastest take-off velocities of 2.8-3.2 m s(-1) had acceleration times of 1.4-1.8 ms. During such jumps, adults experienced an acceleration of 174-200 G: . These jumps required an energy expenditure of 76-225 μJ, a power output of 13-60 mW and exerted a force of 9-37 mN. The required power output per mass of jumping muscle in adults ranged from 24,000 to 27,000 W kg(-1) muscle, 100 times greater than the maximum active contractile limit of normal muscle. The free-living nymphs were also proficient jumpers, reaching take-off velocities of 2.2 m s(-1). To achieve such a jumping performance requires a power amplification mechanism. The energy store for such a mechanism was identified as the internal skeleton linking a hind coxa to the articulation of a hind wing. These pleural arches fluoresced bright blue when illuminated with UV light, indicating the presence of the elastic protein resilin. The energy generated by the prolonged contractions of the trochanteral depressor muscles was stored in distortions of these structures, and the rapid elastic recoil of these muscles powered the synchronous propulsive movements of the hind legs.