Thought mind-controlling fungus was confined to the realms of award-winning video games and critically acclaimed television shows? Well, so did a lot of us. And it’s my great displeasure to tell you that it is not.
Cordyceps fungi have been in the media a lot lately, thanks to the TV adaptation of popular video game, ‘The Last Of Us’. The real-life version of the fungi has a unique way of living that would be best described as a horror movie come to life. Typical Cordyceps grow inside their host until moving to the brain, and triggering impulses to climb; up grass, trees, rocks, whatever is available. Eventually the host dies, and fungal spores rain down from the vantage point to infect more insects and continue the whole hideous cycle.
This is the part where you shudder.
Luckily, there doesn’t seem to be any fungus that can turn people into ravenous monsters (unless you’ve ever been to a competitive truffle market), but our native bugs aren’t so lucky. Meet the giant wētā fungus, or Cordyceps kirkii. While specialised strains of Cordyceps affect insects like ants and wasps, this particular flavour of nightmare only affects giant wētā, and is vanishingly rare.
Cordyceps kirkii is extremely rare; the holotype (single physical example of the organism when first described) was collected in 1922 on a Stephens Island wētā, with no further documented specimens until 1975, and only one more in 2014. This rarity is probably exacerbated by the rarity of our giant wētā. These giant insects are already threatened, and as such we don’t see many of them walking around, let alone any with great big fungal growths. So it’s likely that the fungus is even more threatened than its hosts, simply from a lack of opportunity.
We don’t really know if the giant wētā fungus has the same mind-controlling effects of its ant and wasp cousins. Honestly, we don’t know much about it at all, with only four recorded sightings and three specimens to work from. What we do know (or at least can give a pretty good guess) is that the main threat to this species is the declining population of its hosts. No host, no fungus.
Wētā filled the same general role of rodents before land mammals came to New Zealand, although their behaviour and diet are quite different. They are older than tuatara – 190,000,000 years. There are over 70 endemic species of wētā in New Zealand, including 11 species of giant wētā. Wētāpunga is the largest of these species. Wētāpunga feed on fresh leaves and prefer native plants with large leaves such as karaka, karamu, māmāngi, māhoe, and kohekohe.
Wētā, even the giant ones, are vulnerable to more than just fungus, and experience significant threats from mammalian predators like hedgehogs and humans. So don’t let a fear of Cordyceps deter you from doing your part to help wētā out; setting up wētā motels in your backyard can give the smaller species a great place to live and thrive.
Find out more about New Zealand’s giant wētā on our website.