The Unilateral Jumping Structures of the Spotted Lanternfly, Lycorma delicatula (Hemiptera: Fulgoridae): A Highly Functional and Integrated Unit

Abstract

Previous research on the jumping structures of insects with strong leaping abilities mainly focused on overall jumping mechanisms. Our study reveals that the unilateral jumping structures (UJSs) of L. delicatula has relative functional autonomy. The UJSs consist of three distinct but interconnected parts: (1) energy storage component: it comprises the pleural arch and trochanteral depressor muscles, with the deformation zone extending about two-thirds of the pleural arch from the V-notch to the U-notch; (2) coupling component: made up of the coxa and trochanter, it serves as a bridge between the energy and lever components, connecting them via protuberances and pivots; and (3) lever component: it encompasses the femur, tibia, and tarsus. A complete jumping action lasts from 2.4 ms to 4.6 ms. During a jump, the deformation length of the pleural arch is 0.96 ± 0.06 mm. The angles ∠ct (angle between coxa and trochanter), ∠fp (angle between femur and pleural arch), and ∠ft (angle between femur and tibia) change by 57.42 ± 1.60, 101.40 ± 1.59, and 36.06 ± 2.41 degrees, respectively. In this study, we abstracted the jumping structures of L. delicatula and identified its critical components. The insights obtained from this study are anticipated to provide valuable inspiration for the design and fabrication of biomimetic jumping mechanisms.

Keywords: biomechanics; exoskeleton; kinematics; locomotion; morphology.

Figure 1

The position of jumping structures on the body of adult L. delicatula. (a) The ventral view of an adult L. delicatula from the mesothorax to abdomen. (b) The ventral view of the metathorax. The right hind leg was cut off to show the altitude difference between the metathorax and abdomen.

Figure 2

The bilateral jumping structures exist in pairs in the metathorax of an adult L. delicatula. (a) The dorsal view. (b) The ventral view.

Figure 3

Detached unilateral jumping structures of adult L. delicatula. (a) Dorsal view. (b) Ventral view.

Figure 4

The energy store part and coupling part of a single jumping structure of adult L. delicatula. (a) The dorsal view, (b) ventral view, and (c) ventral view of the separated parts. The trochanteral depressor muscles were separated from the pleural arch to show the core of them and the tendon. (d) The antapical view of the coxa. There is a hole in the coxa for the tendon to pass through. (e) The separated trochanter.

Figure 5

The deformation of the plural arch before and after jumping. (a) Before jumping. (b) After jumping. The red dotted line indicates the upper boundary of pleural arch; the blue dotted lines indicate the length of deformation. The green dotted line rectangles indicate the deformation zone. The pink dots indicate the endpoints at both ends when measuring the length of the plural arch.

Figure 6

Schematic diagrams of the coupling between the coxa and trochanter.

Figure 7

The position changes between the coxa and trochanter before and after jumping. (a) The dorsal view before jumping. (b) The dorsal view after jumping. (c) The ventral view before jumping. (d) The ventral view after jumping.

Figure 8

Schematic diagrams of the posture of each hind leg segment and tendons in the jumping structures. (a) Before jumping; (b) after jumping.

Figure 9

The jumping-like motion duration observed in L. delicatula while the unilateral jumping structures (UJSs) were manually moved. (a) The process of the jumping-like motion of the UJS. Images at crucial time points from a high-speed video, which was captured at a rate of 5000 frames per second. (b) The duration of the jumping-like motion and normal jumping (N = 10). **** indicates significant difference (p < 0.0001) based on the two-tailed unpaired t-test.

Figure 10

The time variation of (a) the length of the pleural arch, (b) the angle between the coxa and the trochanter (∠ct), (c) the angle between the femur and the pleural arch (∠fp), and (d) the angle between the femur and the tibia (∠ft). Five typical jumping-like motions observed while manually moving the UJS were selected to illustrate these variations, and lines of the same color denote the same jump. The insets in each figure are employed to show the measuring approaches of the variables.

Figure 11

The schematic illustration depicts the jumping action mechanism of the UJS in L. delicatula. It was crafted with reference to the work of Cook et al. [42], integrating relevant concepts and findings from their research to accurately represent the complex biomechanical processes involved in the jumping mechanism. This schematic aims to visually convey the key elements and interactions within the UJS during the jumping action, providing a clear and concise overview for readers to better understand the underlying principles.