Posts Tagged ‘entomopathogenic’

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Real Zombies Scuttle

June 19, 2010
A recent meme that’s proved almost worryingly popular around here is planning for a zombie holocaust. It might sound grim, and even a little crazy, but it’s a diverting enough theoretical exercise. At least, it is for most people – as ever, a few devote a bit TOO much time to it. I’ve actually heard it voiced in a serious tone that we ought to plan for it, as ‘you never know’, and there’s a slim but real risk of the plan being needed.

That’s always tickled me, as the plans people make are always to counter zombies as envisioned by George A. Romero. Romero was good at slow, tense horror films, but his idea of zombies is the least plausible I’ve ever seen. A Romero zombie shambles around, hunting all day and all night until its decaying flesh putrefies too far for it to move. They will eat voraciously, but they do not digest. From this alone we know they are impossible.

Picture the scene – a colossal treadmill, filled with Romero zombies. In front of them, a member of staff sits thumbing idly through a trashy magazine. The zombies, driven by pure, primal instinct, lurch forwards towards their flabby supervisor. The wheel turns all day and all night, as different staff members take their shifts, and in the next room, a generator rumbles. Cheap, renewable electricity for ever!

Romero zombies use energy to move, but they don’t gain energy from any source. They violate one of the most inviolable of physical laws, and for that reason alone they can’t happen.

28 Days Later paints a different picture, with an extremely contagious virus turning people into out of control, murderous animals. The victims are still alive, unlike Romero zombies, and presumably have the same physical weaknesses. As far as I can see, this approach is fairly feasible, although there’s no real virus that does anything close to this.

There’s a more feasible and infinitely more sinister possibility though, one that does happen in the real world, just not to humans. It happens to insects.

Cordyceps uniliteralis is a fungus found in jungles across the world. It acts as a parasitoid to certain specific types of ant – a parasitoid being defined as a parasite which kills its host as part of its normal life cycle.

An ant, picking its way through the jungle floor, might accidentally inhale a spore from a mature fungus. The spore lodges itself inside the ant’s body, and immediately sets about making changes. Any spare soft tissue inside the carapace gets converted to sugars, and any cracks in the carapace are sealed. The ant belongs to the fungus now, and it is not willing to share it with other pathogens. When the host is sufficiently prepared, the fungus begins to alter the chemistry of the ant’s brain. The urge is chemically implanted in the ant to find somewhere at just the right altitude, just the right temperature, and just the right humidity. The ant sinks its mandibles deep into the stem of the plant it’s climbed, and dies. The fungus then works quickly, bursting out of the host’s head and shedding its spores onto the breeze.

There’s something akin to a constant, low level war being waged between ant colonies and this fungus, with the colonies being built purposefully far away from likely spore areas, and ant drones being able to recognise infected individuals, and escort them far, far away from the colony before they reach the final stages.

As if that weren’t enough, there are other strains of this fungus which affect dragonflies, cockroaches, cicadas, beetles, stick insects, bees, wasps, butterflies and moths.

I invite you to dwell on how you’d recognise a human so infected, before their head splits open to release a cloud of spores.

That ought to fuel a few nightmares.

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