Vegetable caterpillar fungi

Dr Peter Buchanan, of Landcare Research NZ Ltd, introduces Ophiocordyceps robertsii – the vegetable caterpillar fungus. Native to New Zealand, this fungus invades moth caterpillars and turns them into mummies!

Transcript

Dr Peter Buchanan

In New Zealand, we have a really special fungus called the vegetable caterpillar fungus. It was actually the first fungus ever described as new in New Zealand, and it’s really important historically, culturally and for its very unusual biology. The vegetable caterpillar fungus is a parasite of a native caterpillar, and its life cycle is very interesting because this fungus is adapted to grow only inside caterpillars. Once it gets inside the caterpillar, the fine threads or hyphae of the fungi grow out, and the food that the fungus needs is the contents of the caterpillar. This caterpillar will retreat into its burrow, and it is sitting with its tail down and its head up. So the caterpillar body gets eaten up, consumed by the fungus living inside it, and obviously the caterpillar doesn't survive for long. As the fungus consumes all of the content of the caterpillar, the caterpillar becomes what we call a mummy. The fungus, having mummified the caterpillar, has to produce its fruiting stage, its reproductive stage – it wants to produce more spores. It can't do it underground in this burrow, it has to do by getting above ground. It does that by growing out of the caterpillar. It grows upwards and it forms this stick-like structure, which grows up through the soil. This stick is only about 10–15 centimetres long and 2–3 millimetres wide. This is small stuff. We look at the detail of them with a microscope. I've never seen them in great numbers, but years ago the Māori seemed to be able to find them in great quantity and they would collect them.

Acknowledgements:

Dr Peter Buchanan, Manaaki Whenua – Landcare Research

Vegetable caterpillar fungus engraving, Pouchet, FA 1855: The Universe or, The infinitely Great and The infinitely Little. London, Blackie & son

Burrowing porina caterpillar, Dustin, CC BY 4.0. Sourced from iNaturalistNZ

Vegetable caterpillar fungus hyphae, Redbox, CC BY-NC 4.0. Sourced from iNaturalistNZ