Lanternfly nymphs: Many ways to land upright
Novel righting strategies allow spotted lanternfly nymphs to land on diverse substrates
Although falling can be catastrophic for humans and other large animals, insects and other small animals regularly fall to escape threats and to seek new resources. This makes landing upright important for evading predators and finding food and shelter. The spotted lanternfly, an invasive, destructive insect pest spreading rapidly in the US, uses cyclical falling and climbing behaviors to expand its range. Tonia Hsieh, associate professor of biology, and researchers from Haverford College and the College of New Jersey used high-speed video to show that this species uses a variety of tactics to securely land upright on leaves and hard surfaces, including novel acrobatic motions while bouncing after impact. Watch.
"We are continuing our research this summer, which includes jumping and terrestrial righting behavior, and implementation of some spiffy deep learning algorithms to aid with position tracking of the complex movements," explains Hsieh. The research is published Interface, The Journal of the Royal Society. In addition to Hsieh, authors are Suzanne Amador Kane, Theodore Bien, Luis Contreras-Orendain and Michael F. Ochs.
Unlike large animals, insects and other very small animals are so unsusceptible to impact-related injuries that they can use falling for dispersal and predator evasion. Reorienting to land upright can mitigate lost access to resources and predation risk. Such behaviours are critical for the spotted lanternfly (SLF) (Lycorma delicatula), an invasive, destructive insect pest spreading rapidly in the USA. High-speed video of SLF nymphs released under different conditions showed that these insects self-right using both active midair righting motions previously reported for other insects and novel post-impact mechanisms that take advantage of their ability to experience near-total energy loss on impact.
Unlike during terrestrial self-righting, in which an animal initially at rest on its back uses appendage motions to flip over, SLF nymphs impacted the surface at varying angles and then self-righted during the rebound using coordinated body rotations, foot–substrate adhesion and active leg motions. These previously unreported strategies were found to promote disproportionately upright, secure landings on both hard, flat surfaces and tilted, compliant host plant leaves. Our results highlight the importance of examining biomechanical phenomena in ecologically relevant contexts, and show that, for small animals, the post-impact bounce period can be critical for achieving an upright landing.