Editor | On 23, Dec 2018

Darrell Mann

So, picture this. You’re a lowly fungus, Cordyceps, and you’re looking to make lovely Cordyceps descendants, as is Nature’s way. The only problem is that you’re tiny and you live in low places, so your ability to spread your spores over large distances is pretty limited. What to do?

It’s a common enough problem in Nature. One that might look something like this if we mapped it onto the Contradiction Matrix:

A conflict, in other words, between your desire to procreate and your lack of height above the ground and lack of any ability to control the dispersal of your spores.

Here, then, is Cordyceps remarkable solution to its problem…

The spores of Cordyceps, first up, invade an ant’s body (Principles 24 and 7), where the fungus grows and consumes the ant’s organs (Principle 25) while leaving the vital organs intact. The fungus then releases chemicals (Principle 28, ‘chemical field’) that cause the ant to (Principle 17) climb a tree and grip a leaf with its mouthparts. After emerging from the ant’s body, the fungus releases spore-filled capsules (Principle 30) that explode during their fall, spreading the infectious spores over the ground below. By forcing the ant to climb a tree, the fungus increases the dispersal of the falling spores and the chance of infecting another ant.

Scary stuff. But even scarier, not so rare in Nature. Parasites that makes an animal change its habits, guard the parasite’s offspring or even commit suicide. While mind-control may sound like something out of a science fiction movie, the phenomenon is very real — and has spawned a new field, neuro-parasitology. As outlined in an article published in Frontiers in Psychology, understanding how parasites “hack” their host’s nervous system to achieve a particular goal could provide new insights into how animals control their own behavior and make decisions.

“Parasites have evolved, through years of co-evolution with their host, a significant ‘understanding’ of their hosts’ neuro-chemical systems,” explains one of the article’s authors, Professor Frederic Libersat from Ben-Gurion University of the Negev in Israel. “Exploring these highly specific mechanisms could reveal more about neural control of animal behavior.”

The article describes some of the sophisticated, cunning and gruesome ways that various parasites outwit and exploit their insect hosts. One method is to affect how an insect navigates. Similarly, a parasitic hairworm causes infected crickets to seek out water — where they drown. The cricket’s suicide enables the worms to enter an aquatic environment for reproduction.

In another type of interaction, called “bodyguard manipulation,” the parasite forces the infected insect to guard its young. One such parasite is a wasp, which injects its eggs into a caterpillar by stinging it. Inside the live caterpillar, the eggs hatch into larvae, which feed on the caterpillar’s blood. Eventually, as many as 80 larvae emerge from the caterpillar’s body before forming cocoons to complete their growth into adult wasps.

However, wasp larvae are vulnerable to predators in their cocoons. To scare potential predators away, one or two larvae remain in the caterpillar and control its behavior through an unknown mechanism, so that it acts aggressively towards predators — thereby protecting the cocoons.

Somehow Principles 7 and 24 are never quite going to make me think the same way again.