14 February 2017

Zombie Insects: Bizarre and Terrifying Parasites

While World War Z is less than likely to happen anytime soon, zombie-like behavior has been scientifically recorded in a wide variety of animals. These natural occurrences are usually the result of vicious parasites, that have the power to eerily influence their hosts’ behavior before ultimately killing them or, in some cases, forcing them to kill themselves.

One of the creepiest of cases is the way a species of Costa Rican wasp, the jewel wasp, enslaves orb spiders for reproduction. The wasp will lay its eggs on the spider’s abdomen in an Alien-like manner and right before it’s ready to cocoon the larva injects a chemical that induces a bizarre phenomenon. The spider, before it eventually gets killed and eaten by the larva inside it, begins building a web but not in the manner it instinctively does. It builds an entirely new kind of web designed to support the larvae’s cocoon, who will build it once it’s done eating the poor spider.

Rivaling this larva species is the female jewel wasp, whose usual victim is a cockroach. The host is eventually consumed for sustenance once it is done acting as living crib of her young. Once she finds her target she injects venom into the cockroach that paralyzes its front legs, and with a second sting to the head the venom disables the roach’s ability to control motor function. The cockroach is now immobilized, much like a gambler glued to a slot in a losing streak, but the wasp has plans for her prisoner. She then guides him by the antennae to his doom, which involves being snacked on for several days and keeping the mother’s larvae warm once she burrows her young into its body.

Wasps are by far not the only parasitic animal to zombify other creatures for their benefit. In fact, the final parasite is not even an insect, but a fungus. The Ophiocordyceps is a microorganism that can not only recognize different species of ants but can induce a mind-controlling brain chemical that forces specific activity in hosts.

This creepy fungus only targets certain species of ants, the theories behind this selectiveness range from different ant life cycles to the fact that the fungus is only able to control the brains of certain species. The few it has targeted, however, have all been administered a unique blend of chemicals, demonstrating that the fungus is more than capable of recognizing different species of insects and altering its techniques to adequately control each one.

What usually happens is that an unfortunate ant will come across the spores of this fungus when looking for food. Once it does it is immediately infected with a cocktail that takes over the creature’s nervous system, forcing it to unwillingly climb up a nearby plant before killing itself on a leaf. The microorganism is then ideally placed for its spores to continue to infect more ants below it once it grows out the back of the dead host’s head. Who needs science fiction when you have real science?