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Zombie-like Behaviour – Parasitized Insects, Cordyceps & Beauveria

Every foray offers up some oddity, some strange new species that I’ve never encountered before. When scanning the forest floor for mushrooms, the order of operations is typically to look for colorful growths that grab your attention, but an odd shape and striking texture can alert you all the same.

I scan the sides of the trail and find small, white, powdery, cotton-swab-like tufts that appear like popcorn sprouting out from the soil. I scratch my head in confusion as I find more and more along the way. This isn’t your typical fungi.

Curious, I lightly touch the ends, and white spores instantly powder my fingertips. A small cloud forms and thousands of particles drift slowly to the moss and soil below as if momentarily suspended in a snow globe. I instinctively hold my breath.

Following what looks like antennae, I pull out my pocket knife to excavate whatever is buried beneath the surface. Carefully removing clods of clay, I uncover a small cicada nymph that has burrowed underground to feed on sap from roots. But it’s too late, and another is doing the feeding. It’s dark maroon shell is overtaken by a parasitic fungus…

Cordyceps / Isaria sinclairii (Tatarakihi)

The name comes from the Greek word kordyle, meaning “club”, and cephali, meaning “head.”

The growths protruding from the cicada pupa (tatarakihi) consume and sprout out to more prominent sizes than the host. The antennae stretch upwards and out from the Earth, with the powdery spore-cluster acting as a beacon, ready to spread through the airwaves to make contact and infect other insects.

Cordyceps has what is called a neurophilosophic effect on its victims – in a word, brainwashing. This is something it does in insects – a bizarre but common capability of many species. Cordyceps can synthesize its host’s brain chemistry, hijacking its minds and causing it to do things beneficial to the spread of the fungus.

Cordyceps sinclairii
A cicada larvae infected with Cordyceps sinclairii

The fruiting body’s filament tapers up to the spore anther – delicate for all its deadliness, brings to mind a slender flower stamen. Some frail new tendril raised overnight by mysterious plant turgor, an alien life with its own secret yearning for light and life and open air.

Isaria is the name of the anamorph (asexual reproductive stage); the teleomorph is Cordyceps (the fruiting body or sexual reproductive stage).

Cordyceps are thought to be teleomorphs of a number of anamorphic, parasitic fungi. Essentially, the fruit body has a bunch of flask-shaped, very tightly interwoven hyphae. Inside are sexual spore-bearing cells. These contain thread-like ascospores that break off the fruit body and infect other insects that come into contact.

Thoughts pop into my head of zombie apocalypses and The Last of Us videogame where an outbreak of mutant Cordyceps fungus ravages the United States, transforming its human hosts into aggressive creatures known as the ‘Infected.’

After witnessing the complex shapes borne by the pathogen invading and replacing the host tissue, a morbid curiosity is piqued.

One species complex (not known to be in NZ), Ophiocordyceps unilateralis, is known for its parasitism on ants. It alters the ants’ behavior to propagate itself more effectively, killing the ant and then growing its fruiting bodies from the ant’s head and releasing its spores.

Parasites commonly manipulate host behavior, and among the most dramatic examples are diverse fungi that cause insects to die attached to leaves. This death-grip behavior functions to place insects in an ideal location for spore dispersal from a dead body following host death.

A 48-million-year-old fossil of an ant in the death grip of Ophiocordyceps unilateralis was discovered in Germany.

A leaf shows the bite marks of an ant infected by a fungus. The imprint of the “death grip” bite is so unique that researchers were able to match modern samples with the ancient fossil.

In a mind-blowing, Our Planet clip, one can witness this parasite taking control. An ant is possessed, the fungus uses the host as a vessel. It climbs up a plant away from the nest and performs a final death bite. Tethered to the plant, the parasite fully consumes the ant and sprouts a fruiting body out through the head. Being this high up provides ideal conditions that allow the parasite to distribute spores more effectively.

Despite the morbidness of the fungus, Isaria sinclairii and similar vegetable caterpillar species such as Ophiocordyceps sinensis have been used in traditional Tibetan and Chinese medicine as tonics believed to impart eternal youth. Yartsa gunbu or (“summer-grass, winter-worm”) has been used for many centuries.

Cordyceps have long been used in traditional Chinese medicine to increase energy, treat asthma and improve libido.

It is said that the benefits of Cordyceps consumption were first discovered when herders in the Himalayas observed that yak, goat and sheep which had eaten the mushroom became very strong, stout, and frisky.

The local people then used the fungus to improve the vitality of their cattle, and it was not long before the locals themselves started consuming it. The locals claimed it had aphrodisiac effects and it became known as Himalayan Viagra.

Cordyceps made headlines in 1993 during the Beijing Olympic games when several Chinese runners smashed various world records and attributed their success to eating Cordyceps mushrooms.

This popularization of using the fungus to improve one’s health has led to a dramatic fungal commodification of the rural Tibetan economy. The income from the sale of Cordyceps often accounts for 70%–90% of a family’s annual cash income in areas where it grows.

A pound fetches as much as $50,000 and is one of the world’s most expensive fungus.

There are over 600 species of Cordyceps worldwide

A sphingolipid derivative produced by I. sinclairii, myriocin, was discovered to have powerful immunosuppressive properties, a function of how the fungus attacks living insects. 

Because myriocin is too toxic to use in humans, a synthetic derivative was developed in 1992, named FTY720 or fingolimod. Under its trade name Gilenya, fingolimod was approved by the FDA in 2010 as the first oral drug for treating the autoimmune disease multiple sclerosis. 

Fingolimod also shows promise as a cancer medication and has been tested as a possible treatment for obesity.

Another use case is that some Cordyceps species have biochemical and pharmacological properties. Cordycepin is the source of Cyclosporin – an immunosuppressive drug helpful in human organ transplants.

Ophiocordyceps robertsii – New Zealand vegetable caterpillar

Ophiocordyceps robertsii /  Āwheto

Like the yartsu gunbu of the Tibetan plains, indigenous Maori have a long history of using āwheto, also known as the vegetable caterpillar (Ophiocordyceps robertsii) for traditional tā moko (tattooing). Maori ancestors discovered where āwheto were and collected many to get the black color required to make ink. When burnt, the āwheto turns black and can be ground up into a powder and mixed with mahoe berries, bird fat, various gums, and oils. Recent studies have shown O. robertsii to contain antiseptic chemicals that prevent infection, so it would make sense to use with tā moko.

One evening, before bed, I was scrolling through iNaturalist and a user uploaded O. robertsii found on his property out on Portobello Peninsula in Dunedin. Excited, I shot him a message and met up the next day to go on a foray. “I hope it’s not too weird that I ask to come out and view your parasitized caterpillar!” I tell him. After explaining the importance of the fungus, how it’s been on my bucket list for a while, and that finding such a thing, especially in the Otago region this far south, is a very rare occurrence, he led the way.

We reached the top of a hill and came upon small stick-like stroma popping up from the soil. To the untrained eye, they camouflage very well into the understory. To have the sense to excavate is instinctual, and I dug one out to examine further. To finally bear witness to such an extraordinary fungus is a top mushroom-hunting moment of mine.

Beauveria

Being distinctly different compared to the typical Cordyceps structure, another parasitic fungus is Beauveria. The insects that fall prey to this fungus have white patches or bands erupt through softer chinks in their body plates.

I have found myriad insects infected with Beauveria: beetles, weevils, wasps, and moths. Mantids, stick insects, vegetable bugs, and sometimes spiders.

I find that once you spot a certain kind of fungi, you’ll become more aware of them while out in the bush. I tend to find Beauveria bassiana, or as mycologist Marie Taylor commonly called it, “sugar bonbon disease,” infecting insects that are hiding under soil or near spider webs in crevices off the side of the track.

Beauveria bassiana
A Sphictostethus nitidus infected with Beauveria / Icing sugar fungus

There are useful, practical applications for Beauveria bassiana / “icing sugar fungus.” This includes bio-insecticides to be used against bed bugs. 100% of the bed bugs are eliminated within five days when exposed to cotton fabric sprayed with fungus spores. 

Malaria-carrying mosquitos are also controlled when B. bassiana is applied to mosquito nets in a wettable powder form. 

Beauveria bassiana
Wasp infected with Beauveria / Icing sugar fungus

No matter the size, even the smallest micro-organisms serve a purpose within the ecosystem and are essential in regulating the ecological balance of nature. 

There are a couple other Cordyceps species worth mentioning that have been on my radar. Most recently featured on RNZ’s Critter of the Week, the Cordyceps kirkii. This species of Cordyceps infects Giant Weta. This species is rare and has only been recorded a handful of times, the first being in 1922.

Cordyceps kirkii on Deinacrida rugosa (PDD 104358). Photo: Peter Buchanan, Landcare Research.

Another is Ophiocordyceps humbertii, which infect wasps.

As I come across more species of Cordyceps found in New Zealand they will be added to this post. Have you ever encountered Cordyceps in the bush before? Leave a comment below!

References:

Barbarin, Alexis M., et al. “A Preliminary Evaluation of the Potential of Beauveria BASSIANA for Bed Bug Control.” Journal of Invertebrate Pathology, vol. 111, no. 1, 2012, pp. 82–85., doi:10.1016/j.jip.2012.04.009.

Benahm, W.B. “Art. II.—Note on Cordyceps Sinclairii, Berkeley.” Paperspast.natlib.govt.nz, 12 Sept. 1899, paperspast.natlib.govt.nz/periodicals/TPRSNZ1899-32.2.4.1.2.

Chiba, K. Discovery of fingolimod based on the chemical modification of a natural product from the fungus, Isaria sinclairii. J Antibiot 73, 666–678 (2020). https://doi.org/10.1038/s41429-020-0351-00528.

“Cordyceps.” Cooper Creek Wilderness, 24 July 2015, coopercreek.com.au/cordyceps.

Evolve Further. “Is a Parasitic Fungus the Secret to Athletic Performance?” Evolve Further, Evolve Further, 8 Nov. 2020, https://www.evolvefurther.com/learn/cordyceps.

Hughes DP, Wappler T, Labandeira CC. Ancient death-grip leaf scars reveal ant-fungal parasitism. Biol Lett. 2011;7(1):67-70. doi:10.1098/rsbl.2010.0521

Science Learning Hub – Pokapū Akoranga Pūtaiao. (2014). Vegetable caterpillar. Retrieved from https://www.sciencelearn.org.nz/resources/1435-vegetable-caterpillar

Taylor, Marie. Mushrooms and Toadstools. Reed Books, 1982.

Winkler, Daniel. “Yartsa Gunbu (Cordyceps Sinensis) and the Fungal Commodification of Tibet’s Rural Economy.” Economic Botany, vol. 62, no. 3, 2008, pp. 291–305., doi:10.1007/s12231-008-9038-3.

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Joseph Pallantehttps://nzfungi.com
An avid traveller, Joe enjoys spending time exploring the New Zealand countryside. In his spare time, he travels around in his campervan, writes about nature, and takes photos of fungi.

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