This tiny parasitic wasp can pierce plastic | ET REALITY


When Matvey Nikelshparg was 13, he was obsessed with parasitoid wasps, small insects that lay their eggs on or inside other insects. Under a microscope in a laboratory he had set up at home, he discovered that one species had a surprising superpower: he could use an organ protruding from his abdomen to pierce a plastic Petri dish.

Nikelshparg said his “astonishment reached its peak” when he observed that the wasp had not only pierced the Petri dish, but had laid an egg outside the container that later hatched into a healthy adult. The young researcher, who recently began earning his bachelor’s degree at Saratov State University in Russia, reported on his discovery last month in The Hymenoptera Research Magazine.

Eupelmo messene It is the whisper of a wasp. Smaller than a grain of rice and harmless to humans, this tiny arthropod pierces hardened plant growths, called galls, with an organ called an ovipositor. The insect’s target is the larvae of others Species of wasps, which lay their eggs inside the galls in an effort to protect them from danger. By piercing the botanical fortress of its prey, E. messene it grants its young a prepared meal and, ironically, grants it the same protection from the elements that its target originally sought.

In his experiments at home, Mr. Nikelshparg had set out to study what would happen if there were several E. messene wasps and only one host larva. He placed a host in a Petri dish with 12 females.

Most of the wasps immediately rushed to prick the larva with their ovipositors, he said, “and began pushing and biting each other in a competitive struggle for reproduction.”

But one wasp, curiously, decided to stay away from the tumult. Nikelshparg saw her opt for a different “host”: the Styrofoam wall of the plate itself.

Mr. Nikelshparg reported his discovery to his mentors, Vasily Anikin of Saratov State, Alexey Polilov of Lomonosov Moscow State University, and his sister Evelina Nikelshparg, also in Moscow State. They raised more wasps in the hope of seeing more plastic perforations.

Of the 56 wasps the researchers raised, eight bored holes in the plastic, including three that did so even though a perfectly good host was sitting on the plate with them. The tedious process could last more than two hours, and the wasps often left their work in progress to eat lunch or drink water before returning. One worker wasp drilled five different holes throughout the study.

E. messene has to work harder to get through Styrofoam than a plant gall. The wasp pushes its ovipositor downward while rotating it in both directions, although not like the completely circular motion of an electric drill. Once it has passed through and laid its egg, the wasp removes its ovipositor with “very rhythmic and abrupt upward movements,” Nikelshparg said. So-called expulsion movements have never been observed when parasitoids pierce gills, suggesting “that wasps of this species are indeed flexible in their drilling behavior.”

Uroš Cerkvenik, a biologist at the University of Ljubljana in Slovenia, who was not involved in the study, said it was interesting that the wasp was able to penetrate the soft Petri dish. It is believed that wasps normally exploit small cracks in the surface of a gall, but plastic “presumably has no such cracks,” he said. While this study does not address how plastic is punctured, Dr. Cerkvenik said he would not be surprised if wasps had an anatomical structure or behavior that reinforced their ovipositors to avoid damaging them and their ability to reproduce.

Unsurprisingly, finding a nearly microscopic wasp that can pierce plastic has raised more questions than answers. “Does piercing the plastic wear out the ovipositor?” Mr. Nikelshparg asked. And why don’t any of the other 14 related species he studied also pierce plastic? Answering this mystery may also help understand the piercing tools of other insects, such as the mouthparts of disease-carrying mosquitoes, and could even lead to the invention of new human tools.

“I wouldn’t be surprised if wasp-inspired needles became a common piece of standard surgical equipment,” Dr. Cerkvenik said.

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