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Read: The wasps that steal the body dominate the animal kingdom
The wasp strategy makes sense because it is not strong enough to carry a fully developed cockroach in its lair. She needs a mobile but flexible device, so she has developed a worrisome venom that does not kill or immobilize, but instead turns her victim into a senseless zombie. This capacity, which has been revealed by the work of Frédéric Libersat and others, has been the subject of many writings. But such writings, including this article, usually begin when the wasp has the upper hand. And as Ken Catania has understood, this is not always the case.
A neurobiologist at Vanderbilt University, Catania has a long experience in finding unusual animals, which he often studies alone. He has worked on mole-nosed moles, tentacle snakes, naked mole rats, electric eels, crocodiles and, of course, humans. "I like getting direct experience of the animals that I find most interesting," he says. "I'm teaching the Emerald Cockroach wasp, so I went from the front and I had it. I thought I would just start filming them to show students and expand my lectures, especially the Halloween one. "
His videos, filmed at high speed, showed that the attacks of the wasp concern only the pronotum. If she has her jaw on that plate and provides the first sting, "the game is over," says Catania. This happens about half the time without incident, usually when the wasp takes the cockroach out of the blue. But often, the cockroach defends itself.
First, he turns his side to the wasp, spreads his legs like stilts and nods. This not only keeps the pronotum vulnerable out of reach, but also tilts the sharp spines from the cockroach's leg to the wasp. These spines can inflict heavy damage and are also riddled with sensitive nerves. These, combined with the rapid antennae of the cockroach, follow the wasp movements and warn of potential cracks. In reality, the cockroach becomes a living fence made of barbed wire, equipped with moving lights.
This posture has another advantage: it allows the cockroach to emerge. "Crickets and grasshoppers give defensive shots, but they are built in advance for that. the cockroach is not, says Catania. "And he has a very different form." A cricket spreads outward by quickly lengthening its bent legs, but a cockroach will completely extend a leg, wrap it back, and then tip the extended limb like a baseball bat. "The kicks almost always landed right on the wasp's head," says Catania. "After receiving about five of those shots, he simply gives up."
Even if all else fails and the wasp picks up the pronotum, the cockroach still has a chance. He can now use the thorns of his legs to remove the parasite, trim his sting or even stab it. If successful, the results can be fatal for the wasp. When Catania acquired his wasps for the first time, he made the mistake of leaving them alone with a big cockroach. A few hours later, he came back and the wasp was dead, probably because of stab wounds.
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