Sharpshooter Droplet Dynamics: Real Time Sharpshooter Insect Droplet Ejection Part 1 of 3

Original video: https://youtu.be/Vg3pX08UUW0

Food consumption and waste elimination are vital functions for living systems. Although how feeding impacts animal form and function has been studied for more than a century since Darwin, how its obligate partner, excretion, controls and constrains animal behavior, size, and energetics remains largely unexplored. Here we study millimeter-scale sharpshooter insects (Cicadellidae) that feed exclusively on a plant’s xylem sap, a nutrient-deficit source (95% water). To eliminate their high-volume excreta, these insects exploit droplet superpropulsion, a phenomenon in which an elastic projectile can achieve higher velocity than the underlying actuator through temporal tuning. We combine coupled-oscillator models, computational fluid dynamics, and biophysical experiments to show that these insects temporally tune the frequency of their anal stylus to the Rayleigh frequency of their surface tension-dominated elastic drops as a single-shot resonance mechanism. Our model predicts that for these tiny insects, the superpropulsion of droplets is energetically cheaper than forming jets, enabling them to survive on an extreme energy-constrained xylem-sap diet. The principles and limits of superpropulsion outlined here can inform designs of energy-efficient self-cleaning structures and soft engines to generate ballistic motions.

This video showcases the fascinating process of droplet ejection in sharpshooter insects. It includes:

(a) Real-time footage of a glassy-winged sharpshooter ejecting droplets.

(b) High-speed video (4484 fps) of a blue-green sharpshooter, highlighting the distinct phases of droplet ejection in slow motion.

(c) Demonstration of 'pee' puddle accumulation at significant distances due to continuous droplet ejection.

(d) Visualisation of the parabolic trajectory and the consistent repeatability of droplet ejections.

(e, f) Manual manipulation showing the elasticity of the anal stylus.

(g) Comparison of droplet dynamics between control and hairless sharpshooters, revealing larger droplet deformation during ejection in hairless sharpshooters.

Watch part 2: https://youtu.be/0iJXAdjgzz8 Watch part 3: https://youtu.be/IEy9SG34B1g Keywords: Real-Time Video, Glassy-Winged Sharpshooter, Insect, Ejecting Droplets, High-Speed Video, Blue-Green Sharpshooter, Droplet Ejection

Citation:

Challita, E.J., Sehgal, P., Krugner, R. et al. Droplet superpropulsion in an energetically constrained insect. Nat Commun 14, 860 (2023). https://doi.org/10.1038/s41467-023-36376-5

Published on: 28 February 2023

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