Adhesive latching and legless leaping in small, worm-like insect larvae

Abstract

Jumping is often achieved using propulsive legs, yet legless leaping has evolved multiple times. We examined the kinematics, energetics and morphology of long-distance jumps produced by the legless larvae of gall midges (Asphondylia sp.). They store elastic energy by forming their body into a loop and pressurizing part of their body to form a transient 'leg'. They prevent movement during elastic loading by placing two regions covered with microstructures against each other, which likely serve as a newly described adhesive latch. Once the latch releases, the transient 'leg' launches the body into the air. Their average takeoff speeds (mean: 0.85 m s −1 ; range: 0.39-1.27 m s −1) and horizontal travel distances (up to 36 times body length or 121 mm) rival those of legged insect jumpers and their mass-specific power density (mean: 910 W kg −1 ; range: 150-2420 W kg −1) indicates the use of elastic energy storage to launch the jump. Based on the forces reported for other microscale adhesive structures, the adhesive latching surfaces are sufficient to oppose the loading forces prior to jumping. Energetic comparisons of insect larval crawling versus jumping indicate that these jumps are orders of magnitude more efficient than would be possible if the animals had crawled an equivalent distance. These discoveries integrate three vibrant areas in engineering and biologysoft robotics, small, high-acceleration systems, and adhesive systemsand point toward a rich, and as-yet untapped area of biological diversity of worm-like, small, legless jumpers.

Beyond power amplification: latch-mediated spring actuation is an emerging framework for the study of diverse elastic systems

“…(C) The launch phase (blue; used in calculations in Box 3) is very brief compared with the whole trajectory (inset). B and C were created from figures and data in Farley et al (2019).…”

“…Jumping gall midge larvae were analyzed during launch as defined here ( Fig. 1; data from Farley et al, 2019). In contrast, mantis shrimp [data from Cox et al (2014), Blanco and Patek (2014), and unpublished mass data (S.N.P.)]…”

Latch-based control of energy output in spring actuated systems

“…By using LaMSA mechanisms, small and lightweight organisms achieve accelerations and velocities far beyond what their muscles and actuators can accomplish alone. Trap-jaw ants (mandible strike: 64 m s −1 at an average acceleration of the order of 10 6 m s −2 ) [7][8][9][10][11][12][13], mantis shrimp ( predatory strike: up to 31 m s −1 at an average acceleration of the order of 10 4 m s −2 ) [14][15][16][17][18], froghoppers ( jump: 4.7 m s −1 at an average acceleration of the order of 10 3 m s −2 ) [19,20], and even soft-bodied gall midges ( jump: 0.88 m s −1 at an average acceleration on the order of 880 m s −2 ) [21] are just a few examples. Furthermore, LaMSA mechanisms are used in a variety of organisms for diverse applications ranging from prey capture and predator evasion, to jumping locomotion.…”

Optimal leap angle of legged and legless insects in a landscape of uniformly distributed random obstacles

“…A similar hydrostatic catapult mechanism is adopted by the larvae of the gall midge (Asphondylia sp.) [8]. In this case, latching is achieved by micrometre-scale finger-like microstructures distributed across the width of body segments.…”