Watch these glassy-winged sharpshooters fling pee bubbles with anal catapult

The glassy-winged sniper drinks so much water that he pees frequently and excretes up to 300 times his body weight in urine each day. Rather than producing a steady stream of urine, the sniper forms droplets of urine in his anus and pushes those droplets away from his body at a staggering speed that boasts ten times the acceleration of his Lamborghini. In a new paper published in the journal Nature Communications, Georgia Tech scientists have found that insects use this unusual “superpropulsion” mechanism to conserve energy.

A kind of leafhopper, a sniper with glassy wings (Homalodisca vitripennis) Technically an agricultural pest, it has been a bane to Californian winemakers, especially since the 1990s. It feeds on many plant species (including grapes) and sucks out the sap by piercing the xylem of the plant (which carries water from the root to the stem and leaves) with its needle-like mouth. Insects consume a lot of sap, and due to their small size and the sap’s viscosity and negative surface tension (which naturally draws them inward), frequent urination consumes a lot of energy. However, since sap is about 95% water, it contains very few nutrients that cause pee.

“If you were only drinking diet lemonade and that was your entire diet, you wouldn’t want to waste energy on any part of the biological process.” “

Bhamla and his colleagues used high-speed imaging to study the dynamics of glassy-wing snipers in the laboratory. The key to pee throwing is something called an anal stylus, and the team observed him in three different stages of urination. First, the stylus rotates to squeeze out the pee bubbles. After reaching a certain size at about 80 ms, the stylus rotates some more, essentially spring-loading the droplet. Finally, the stylus rotates one more time quickly, ejecting a droplet of urine. A droplet can move him 40% faster than a stylus (i.e. super-propulsive regime). When enough insects do this at the same time, a “leafhopper rain” occurs.

The authors noted that the physics of elastic projectiles (such as pee droplets) are well known and require sequential timing and synchronization between the actuator and the projectile to optimize energy transfer and obtain the best propulsion. I am paying attention to the fact that in particular, “[s]Counter-intuitive propulsion is achieved only in elastic projectiles (such as water droplets) by carefully tuning the fundamental actuator vibration frequency to the projectile’s natural frequency,” the authors write.

Bhamla likened the use of a sniper’s anal stylus to a diver jumping off a high dive board. The authors’ model showed that using this hyperpropulsion mechanism required from 4 to 8 times less energy than simply generating urine flow. As an added benefit, projecting urine droplets farther away makes the sniper less likely to be chemically detected by predators such as parasitic wasps.

Also, snipers aren’t the only insects that employ this type of defecation strategy. According to the author, there are many “flash shooters”, “bat flickers” and “und hurlers” in nature. For example, skipper larvae have latches in the anal plate that allow them to raise blood pressure and expel solid pellets, while some Noctuid (moth) species kick pellets away with their thoracic legs. However, this is the first time that super-propulsion has been observed in vivo.

“At its core, superpropulsion provides a gateway for propelling elastic projectiles faster than the actuator’s maximum velocity through temporal adjustments and can be viewed as a single-shot resonant system,” the authors conclude. I was. “For physical systems dominated by surface tension, super-propulsion provides an ingenious mechanism by which this disturbing force can be harnessed as a spring.” Efficient removal of water droplets, self-cleaning systems for wearable electronics, defogging systems for goggles and eyeglasses, and more.

DOI: Nature Communications, 2023. 10.1038/s41467-023-36376-5 (About DOI).

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