These tiny and beautiful wasps eat the hearts of cockroaches | ET REALITY


If you hate cockroaches, you’ll love the emerald jewel wasp.

Females of the species Ampulex compressa, also known as emerald cockroach wasps, measure less than an inch long and are dressed in gorgeous metallic blue-greens. To complete their life cycles, they must first bite an American cockroach and inject mind-control toxins into the much larger insect, turning it into a helpless zombie.

The female wasp then drags the subdued cockroach by her sensitive antennae into a cavity she has found, lays a single egg on the cockroach’s leg, and then uses dirt and debris to seal the fateful pair inside. After six days, the egg hatches and the larva makes its way into the cockroach’s chest. It then begins to devour the defenseless insect from the inside out.

It’s one of the most macabre horror stories you’ll find in nature, and just in time for Halloween.

As scary as it may be, there are around half a million species of parasitic wasps on this planet, and many make a similar living. Scientists love studying these mini-monsters because many wasps focus on insects that humans don’t mind seeing brutalized: creatures like cockroaches, but also crop pests and invasive species.

But there’s something scientists have never noticed about the jewel wasp’s “Cask of Amontillado” routine until now.

“Since the 19th century, people have had this mantra that parasitoids selectively avoid eating the vital organs of their host in order to keep it alive,” he said. Kenneth Catania, a neuroecologist at Vanderbilt University. “And what I have discovered is that this parasitoid goes directly to the heart of the cockroach and eats it.”

Every fall, Dr. Catania prepares a special Halloween-themed class for students in his Behavioral Neurobiology course. One year, he even built a three-room Wes Anderson-style diorama and filmed a wasp dragging its victim through a dollhouse-sized kitchen filled with small, tasty treats to a tomb shaped like a human skull. .

Just to be clear, the video It’s meant to be silly and engaging, the better for students to learn how wasps operate. But behind the cute accessories, it also shows a real ecology in motion. The wasp performs its task perfectly, even going so far as to seal the skull’s eye socket with small pieces of golden plastic treasure, just as Dr. Catania expected it to do.

And so, in another attempt to gain the attention of his students, the scientist set out to film an emerald jewel wasp larva as it fed on the cockroach from the inside.

“That’s how science often plays out for me,” said Dr. Catania, author of “Great adaptations.” “I’m looking at something out of curiosity or art.”

This is how he ended up capturing the larva’s taste for the cockroach heart. But he made an unexpected discovery: After eating the cockroach’s heart, the wasp larva began gnawing on its prey’s trachea, the insect equivalent of lungs. This caused air to escape from the cockroach’s respiratory system and enter its body cavity, air which the wasp larva then eagerly slurped up.

In other words, the emerald jewel wasp devours the cockroach’s heart and leaves it breathless.

After performing the experiment two dozen times, Dr. Catania was able to show that the air bubbles not only allow the larva to breathe while completely inside the cockroach’s body, but also give the little troublemaker a metabolic boost. . Once the air bubbles appear, the larvae begin to chew faster, which Dr. Catania documented this year in a study published in the journal Current Biology.

Within 48 hours, the emerald jewel wasp larva has chewed through so much of the cockroach that the host dies. “You can imagine it as something like ‘Alien,’” Dr. Catania said, referring to the 1979 Ridley Scott film. “Once it’s inside you, it’s game over.”

In fact, the game ends much faster than has been observed with other parasitoids, some of which do not even completely kill their hosts at this stage, but instead keep their victims on life support by avoiding vital organs. That led Dr. Catania to wonder why these wasps evolved to consume with the speed of Joey Chestnut.

That creates a perfect cliffhanger for a sequel to this natural horror movie: Dr. Catania believes the wasp has to eat quickly before its zombified host is devoured by, well, something else. But that’s a discovery he’s not yet ready to publish.

“There’s more to this story,” he said, “and I’m currently working on part two.”

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