Fig. 1: Sharpshooter insects exhibit ultrafast droplet excreta catapulting.
From: Droplet superpropulsion in an energetically constrained insect
a A blue-green sharpshooter (BGSS) Graphocephala atropunctata feeding on xylem fluid on a basil plant stem. The insect sucks fluid using its stylet before excreting the water-based waste in the form of droplets on its anal stylus (anal ligulae). b A close-up microscopic image of the anal stylus of a glassy-winged sharpshooter (GWSS) Homalodisca vitripennis reveals a clear resilin blob near the pivot point at its base and tiny hair projections (sensilla) along its surface. c Confocal image of the stylus (GWSS) reveals that the stylus is a complex composite of chitin (sclerotized) and resilin (flexible). A canal spans along the stylus that channels the excreted fluid during excretions. d Droplet excretion takes around ~100 ms and may be divided into three different phases. 1- Droplet formation, where a droplet excreta forms on the anal stylus. 2- Spring loading, where the insect compresses the resilin located at the anal stylus. 3- Droplet ejection, where the stylus rotates rapidly, ejecting the droplet in the dorsal and posterior plane. Before taking off, the elastic droplet undergoes compression and extension. e Kinematic analysis of the angle between the anal stylus and the insect’s body axis (GWSS, n = 1 individual, N = 3 droplet ejections) highlighting the different excretion phases f Due to the elasticity mediated by the droplet’s surface tension, the max compression time tc and ejection time te occur after the stylus reaches maximum speed. g The max speed of the droplet at ejection Vd is higher than the maximum speed of the stylus Vs (GWSS, n = 5 individuals, N = 22 droplet ejections, mean of means ± STD). The speed ratio λ = Vd/Vs is higher than unity. Po Posterior, Do Dorsal, An Anterior, Ve Ventral. Error bars represent average value ± one standard deviation.
