Putting a new spin on insect jumping performance using 3D modeling and computer simulations of spotted lanternfly nymphs

Abstract

How animals jump and land on diverse surfaces is ecologically important and relevant to bioinspired robotics. Here, we describe the jumping biomechanics of the planthopper Lycorma delicatula (spotted lanternfly), an invasive insect in the USA that jumps frequently for dispersal, locomotion and predator evasion. High-speed video was used to analyze jumping by spotted lanternfly nymphs from take-off to impact on compliant surfaces. These insects used rapid hindleg extensions to achieve high take-off speeds (2.7-3.4 m s-1) and accelerations (800-1000 m s-2), with mid-air trajectories consistent with ballistic motion without drag forces or steering. Despite rotating rapidly (5-45 Hz) about time-varying axes of rotation, they landed successfully in 58.9% of trials. They also attained the most successful impact orientation significantly more often than predicted by chance, consistent with their using attitude control. Notably, these insects were able to land successfully when impacting surfaces at all angles, pointing to the importance of collisional recovery behaviors. To further understand their rotational dynamics, we created realistic 3D rendered models of spotted lanternflies and used them to compute their mechanical properties during jumping. Computer simulations based on these models and drag torques estimated from fits to tracked data successfully predicted several features of the measured rotational kinematics. This analysis showed that the rotational inertia of spotted lanternfly nymphs is predominantly due to their legs, enabling them to use posture changes as well as drag torque to control their angular velocity, and hence their orientation, thereby facilitating predominately successful landings when jumping.

Keywords: Antipredator behavior; Biomechanics; Invertebrate; Locomotion; Maneuverability; Tumbling.

Fig. 1.

Laboratory jumping experiments. (A) Spotted lanternfly nymph third and fourth instars. Gray arrow shows the cranial–caudal axis, , which was tracked to measure body orientation versus time. (Adapted from Bien et al., 2023.) (B) Jumping experiment arena photograph showing the launch pad (bottom right), superimposed images of a spotted lanternfly nymph at different times and the jumping trajectories (dashed yellow line), and the white fabric target (far left) on which they impacted and landed, as seen in the main camera side view and orthogonal top mirror view. (C,D) Spotted lanternfly nymph jumping raw trajectory coordinate data (circles) and 3D ballistic fits (lines) as seen from the (C) side and (D) top views. Here, z is the vertical, x and y are in the horizontal plane.

Fig. 2.

Measuring and simulating rotational kinematics and dynamics. (A) Illustration of the geometry used in defining the quantities used to describe rotational dynamics about a single axis for a point mass: ω, angular velocity; r, moment arm; F, force; m, mass; I_rot, moment of inertia. (B) Geometry for computing moment of inertia, I_rot, for an extended rigid body. (C) Schematic illustration of the principal axes of rotation for an extended body, labeled by their corresponding values of moment of inertia. (D) For zero external torque, angular momentum, L, is constant, so changes in body posture (e.g. from legs extended to legs tucked) that alter moment of inertia, I_rot, also change angular velocity, ω. (E) Illustration of the geometry for torque-free precession, in which the rotational velocity vector, , and its associated axis of rotation (blue arrows) describe a cone about the constant angular momentum vector, (green arrow), even if the external torque is zero. (F) Illustration of the geometry for Eqn 7 and surrounding discussion. The spotted lanternfly is modeled as a counter-rotating body (gray) and rod-like leg (blue box) with a hinge joint shown before rotation (left) and after rotation (right).

Fig. 3.

3D rendered models of spotted lanternfly nymphs. (A) Photographs of specimens taken from multiple views were used with photogrammetry software to create detailed 3D renderings of spotted lanternfly nymph bodies and legs. (B) Video images of a live spotted lanternfly nymph and the 3D models for two stereotyped mid-air postures observed during jumping. (C) Orientation of the principal axes for the two 3D models, showing the definition of the roll, pitch and yaw axes used in this study. (D) Anatomical plane views used for estimating 3D model cross-sectional areas in Table 3. The images of the legs-tucked (blue) and legs-extended (gray) 3D models in each body plane are overlaid to allow a visual comparison of their relative cross-sectional areas. Scale bar: 10 mm.

Fig. 4.

Jumping behaviors. (A) Ethogram of spotted lanternfly nymph jumping behavior divided into observed phases and stereotyped postures, with the time for acceleration during take-off, t_accel, leg extension after take-off, t_ext, and time of flight, t_TOF, indicated. (B) Leg motions during take-off. (C) Stereotyped postures assumed in mid-air during jumping (this study) and falling (Kane et al., 2021).

Fig. 5.

Rotational kinematics. (A–H) Angular velocity of body orientation (cranial–caudal axis), ω_cc, versus time tracked on video and from simulations using parameters measured from the tracked data from take-off (circles) to impact (asterisks). Details of the simulations are described in Materials and Methods. F shows an example of how the oscillation period, T_osc, was measured. (I,J) Image sequence from the video (I) and matching simulations (J) for the data in E; the spotted lanternfly model is shown in the legs-extended posture for all frames.

Fig. 6.

Spotted lanternfly nymph body orientations at impact. Data are shown for (A) all successful landings (n=122 landings, N=85 specimens, 1–4 landings per specimen), (B) all failed landing attempts (n=85 attempts, N=59 specimens, 1–4 attempts per specimen) and (C) all impacts. The error bars are the 95% confidence interval for each measured proportion. The dashed line at 1/6 corresponds to equal probability of landing in each orientation.