Zombifying Fungi

I saw a video on Facebook the other day, of ‘the most disgusting parasite ever’, in which an adult loa loa (a nematode worm) is being removed from a human eye. Please do not watch the video if you’re faint hearted – I watched it whilst eating dinner, not a very good idea..

But it did get me thinking about parasites, and my opinion on what the most ‘disgusting’ parasite is, which can really be changed to the most ‘fascinating’ – because, come on, they are really fascinating!

My immediate answer is fungi. I know, I know, “how can fungi compare to eye-dwelling worms?”, but let me explain.

There are quite a few species of parasitic fungi, mostly in the Cordyceps and Ophiocordyceps genera. They mostly parasitise insects and other arthropods, though a few parasitise other fungi.

 

Cordyceps can take down Tarantulas

The spores of Cordyceps ignota burrow into the body of a tarantula. They start to grow and branch throughout the spider, eventually killing it. Once the fungus has completely taken over, fruiting bodies burst though the exoskeleton and release spores, to complete the cycle.

A tarantula that has been taken over by the Cordyceps ignota fungus. Image Credit: Ian Suzuki [CC BY 3.0] via Wikimedia Commons
A tarantula that has been taken over by the Cordyceps ignota fungus. Image Credit: Ian Suzuki [CC BY 3.0] via Wikimedia Commons
But there’s an even more interesting, and horrifying, species of Ophiocordyceps, which ‘zombify’ ants.

 

Ophiocordyceps make ants bend to their will

Ophiocordyceps unilateralis, or the zombie-ant fungus (no joke), infects the carpenter ant, which live in tropical rainforests.

The fungus takes over the ant’s body, and eventually gets into its brain. The freaky thing is that the fungus can actually control the ant. The ant becomes a fungus zombie. The fungus makes the ant find perfect conditions for it to spore – on the underside of a leaf not far from the ground.

The ant bites down on the leaf in a ‘death grip’. Once the ant’s job is done, the fungus eats it from the inside and grows out from the ants head to release more spores. Other ants are unwittingly infected by these spores and the cycle continues. The precision in which the fungus makes the ant perform this ‘death-grip’ has astounded researchers.

Ophiocordyceps unilateralis growing out of a ‘zombified’ carpenter ant. Image Credit: David P. Hughes [CC BY 2.5] via Wikimedia Commons
Ophiocordyceps unilateralis growing out of a ‘zombified’ carpenter ant. Image Credit: David P. Hughes [CC BY 2.5] via Wikimedia Commons
There are many species of these fungi puppet masters, which have been specialising in parasitism for at least 48 million years.

 

Parasitising the parasite

The story becomes even more surreal when another parasitic fungus joins the mix. The secondary fungus (or hyperparasite) grows over the dead ant and the emerging stalk, which completely prevents the ‘zombie-ant’ parasite from producing spores. What’s more is that these fungi hyperparasites specialise on infecting different species of fungi parasites.

 

Are humans next?

Luckily for us, this is not The Last of Us – a video game where 60% of humanity is wiped out by a parasitic Cordyceps, which turns people into, you guessed it, zombies.

Unlike other parasites, such as the malaria virus which makes infected people more attractive to mosquitos, parasitic fungi cannot parasitise us, let alone influence our behaviour.

In fact, a few fungi in the Cordyceps genus have medicinal value. Cordyceps subsessilis has been used in immunosuppressive drugs for organ transplants. So the zombifying killer is actually helping us survive – who would have thought?

In my opinion, a fungus that can zombify and control other creatures is by far the most sinister and fascinating of all parasites. Though, I’d really enjoy hearing your opinion on what the most ‘disgusting’ parasite is. Please comment below! 🙂

 

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6 Responses to “Zombifying Fungi”

  1. Asher Trama says:

    When I first saw the image of the cordyceps covered tarantula, I thought, ‘wow, no wonder people think drawing flames on things makes it look cool – we got the idea from this’ 😛

  2. jrowland says:

    Wow that’s so cool! The picture of the spider covered in the fungus is amazing! It looks like tentacles or flames. What a strange and wonderful world we live in 🙂

  3. Asher Trama says:

    Thanks @ruthd1 🙂

    How the fungus controls the ant exactly is still being studied, but researchers think that the fungus can mimic molecules in the ants brain that influence behaviour. Nerve toxins may also be to blame for the uncoordinated movements and hyperactivity of infected ants. I’m not surprised that they may alter the ants perception of pheromones.

    It’s one of those ‘It’s so creepy, it’s cool’ things 🙂

  4. ruthd1 says:

    I’ve heard of the fungus controlled ants before, but I loved how you put it!! ‘Fungi puppet masters’ made me giggle and then stop in creeped out amazement. It’s genuinely one of the coolest (and morbid) things ever. I think I heard that the fungus actually alters the ant’s perception of pheromones, and that’s why it climbs to the leaves. Really cool! Anyway, thanks for an entertaining post 🙂

  5. Asher Trama says:

    Thanks @rpoon1.

    There are a few natural mechanisms that help protect ants. Ants in the colony will move infected ants that are acting strangely away from the nest, so that more ants aren’t infected. The hyperparasitic fungus also helps reduce the effects that the zombie-ant fungus has on ant colonies, and without them whole colonies of ants can be quickly wiped out.

    On the other hand, researchers are trying to harness this parasitic ability of these fungi to control pests for agriculture.

    http://www.scientificamerican.com/article/zombie-ant-fungus-parasite/

  6. rpoon1 says:

    Thanks for a really interesting post Asher. Fungal disease is usally linked to plants and animals. I never considered fungi attacking insects before. Are there any methods to prevent the fungi from affecting insects?