As some of you may know, I’m a big fan of zombies. Not the feet-dragging, flesh-rotting stereotypes found on B-grade horror movies (although they can be cool too) but the ones found in real life. The ones that make you wonder whether human zombies are for real. The science behind these phenomena is fascinating but absolutely terrifying. Creatures that suddenly exhibit irrational behavior or complete odd and highly specific tasks. (Don’t worry, your girlfriend is (probably) not a zombie.) I already wrote a bit about T. gondii (link) but a recent article in the journal BMC Ecology (abstract) describes an even more horrifying example. Zombie ants. I’m thinking this would make a great sequel to A Bug’s Life.
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| Zombie ant with fruiting body |
It starts with a simple fungal infection and before long the ant is no longer following the well-marked ant trails through the Thai rainforest. It starts staggering and has the occasional convulsion but instead of heading to rehab, it falls out of the tree and onto the forest floor. At solar noon, the ant stops its random stagger and makes a bee-line to a nearby sapling. It clamps its mandibles into a leaf (almost always a primary vein, under the leaf, facing NNW, about 25 cm high) and dies. Bizarre? Yes, but to the fungus it is all part of a diabolical plan (cue music). In order to reproduce, the fungus (Ophiocordyceps unilateralis) requires a very specific temperature and humidity. An environment not present in the canopy (where the ants are) but uniformly at about 25 cm from the forest floor. What’s an evil fungus to do? In order to get there, the fungus hijacks the ant and manipulates its brain by releasing various chemicals and poisons as well as making specific morphological changes to the mandibles. All of these activities are designed to get the ant out of the canopy, go to a specific environment, and have the ant remain attached there after death. Then the fungus sprouts a fruiting body out of the ant’s head to release spores. All in all, the amazing transformation from ant to fruiting body takes about 2-3 weeks. Many of the details are still a mystery but the Hughes paper begins to shed some light on this process. A process, incidentally, that is very ancient. Another paper by Hughes (abstract) describes fossils from the Tertiary Period (from about 50 million years ago) that bear mandible scars on primary veins of leaves. Could these be the echoes of ancient zombie ants? Could our own legends be the echoes of human zombies? I wouldn’t worry too much unless your spouse’s ‘honey-do’ list becomes very bizarre or your girlfriend’s new hat looks suspiciously like a fruiting body.
2 comments:
Your blog combined with images from Super 8, which I saw yesterday, will probably lead to some nasty nightmares....
Any nightmares? These zombie ants are more frightening than most horror flicks I watch. I think it is also cool that other ants can sometimes detect the infection early on and will throw the ant out of the tree.
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