Cockroach Karate-Kicks Wasp To Avoid Becoming Brainless Zombie

cockroach karate
A cockroach delivering a blow to the parasitic wasp. Vanderbilt University

A cockroach has been filmed karate kicking a parasitic wasp to save itself from becoming a zombie.

Ken Catania, a biologist at Vanderbilt University in Tennessee, was studying the interactions between predators and prey when he found out that cockroaches try to defend themselves against wasps that try to use their bodies as hosts for their larvae.

Emerald jewel wasps are a solitary species known for their unusual reproductive traits. The female stings the thorax and brain of the American cockroach in order to take control of its behavior. The wasp lays its eggs in the cockroach and over the next few days, the hatchling eats the cockroach alive from the inside out.

Recently, scientists discovered the sting administered to the cockroaches brain delivers a neurotoxin that causes it to vigorously groom itself before falling into a state of rest, at which point the wasp larvae start feeding.

In a study published in the journal Brain, Behavior and Evolution, Catania has now described how the cockroach attempts to defend itself to avoid this braindead zombie fate.

Using ultra slow speed video, Catania showed how the cockroach delivers blows to the wasp with its back legs to stop the wasp delivering its first paralyzing sting. And in good news for the cockroach, he found these karate kicks work about 63 percent of the time among adults. Juveniles were less successful, almost always losing the battle.

"The cockroach has a suite of behaviors that it can deploy to fend off the zombie-makers, and this starts out with what I call the 'en garde' position, like in fencing," he said in a statement. "That allows the roach to move its antenna toward the wasp so it can track an approaching attack and aim kicks at the head and body of the wasp, and that's one of the most efficient deterrents. It's reminiscent of what a movie character would do when a zombie is coming after them."

Normally, he said, the wasp works out the fight is over and seeks out a younger, less defensive host for its young. "For a cockroach not to become a zombie, the best strategy is: be vigilant, protect your throat, and strike repeatedly at the head of the attacker," he concludes.