Unusual jumping behavior recorded in beetle larvae • Earth.com

There are a few species of beetles that can jump, but beetle larvae have a tendency to wriggle over the substrate and have never seen acrobatic jumps to date.

A team of researchers has published a scientific paper documenting the jumping behavior of larvae-clad flat bark beetles (Laemophloeus biguttatus). This type of locomotion has not been previously recorded for beetle larvae.

The larvae can leap into the air at a speed of about 0.5 meters per second and travel a distance roughly equal to four times their own body length. As it flies through the air, the larva curls itself into a loop, and as it lands, it bounces and rolls along until it comes to a stop.

“The jumping is extremely rare in the larvae of beetle species, and the mechanism they use to perform their jumps has not been previously recorded in insect larvae as far as we can tell,” said study co-author Matt Bertone, director of the study. of Plant Disease and Insect Clinic of North Carolina State University.

“The way these larvae jumped was impressive at first, but we didn’t immediately understand how unique it was,” says Bertone. “We then shared it with a number of beetle experts across the country, and none of them had seen the jumping behavior before. Then we realized we needed to take a closer look at how the larvae were doing exactly what they were doing.”

When insects make impressive jumps, they usually rely on a “bolt-mediated spring actuation mechanism”. This means that two parts of the body snap together as the insect exerts force with its muscles. When this builds up a significant amount of potential energy, the insect unlocks the two parts and releases all of the stored energy at once. This results in an action-packed spring off the ground.

The researchers looked for a two-part locking mechanism on the surface of the coated larvae of the flat bark beetle and found nothing. They then measured the muscle strength of the beetle larvae using microCT scans and calculated whether this would provide enough force to shoot the larvae into the air at a speed of 0.5 meters per second. The larvae did not have enough muscle to accomplish this through muscle action alone.

The conclusion was that the larvae had to use some kind of spring system to make their acrobatic jumps. This is when Bertone and co-author Adrian Smith decided to film the behavior to get a better understanding of what was happening. Smith is a research assistant professor of biological sciences at NC State and chief of the Evolutionary Biology & Behavior Research Lab at the North Carolina Museum of Natural Sciences.

The team filmed several jumps at 60,000 frames per second and could see the beetle larvae hooking their feet into the ground as they flex their bodies and prepare to jump. As soon as a foot loses grip on the ground, the spring is released and the larva is propelled into the air by the force of the body’s own potential energy supply.

“What makes the L. biguttatus so remarkable is that it makes these jumps without snapping two parts of its body together,” said Bertone. “Instead, it uses claws on its paws to grip the ground as it builds up that potential energy — and once those claws releasing their grip on the ground, that potential energy is converted to kinetic energy, launching it toward the sky.”

Meanwhile, in an unrelated video about jumping maggots, Smith had included a short clip of the jumping behavior in L. biguttatus. That video was seen by Takahiro Yoshida, a researcher from Tokyo Metropolitan University in Japan, who had witnessed similar jumps in the larvae of another beetle species called Placonotus testaceus, but had not published anything about the behavior. Yoshida is co-author of the publication on this unusual form of locomotion.

“We don’t have high-speed footage of P. testaceus, but the video evidence we have from Yoshida’s lab suggests that this previously unknown behavior is found in two different sexes that aren’t even closely related,” Bertone said.

“This raises many questions. Did this behavior evolve separately? Does it occur in other beetle species? Are these genera more closely related than we previously suspected? There is a lot of interesting work to do here.”

Details of this unusual mode of locomotion in coated flat bark beetle larvae are published today in the journal PLOS ONE.

Through Alison Bosman, Earth.com Staff Writer

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