Nav: Home

'Himalayan gold' on the brink

October 23, 2018

A parasitic fungus that grows wild throughout the Himalayas and sells for more than its weight in gold could vanish if current harvesting and climate trends continue, according to new research from Stanford University.

The fungus, Ophiocordyceps sinensis, survives by preying on ghost moth caterpillars in some of the highest reaches of the Himalayas. The fungus infects and eats the insides of a caterpillar that burrows underground for winter. What the parasite does next may be too gruesome to mention over a supposedly healing bowl of aphrodisiac soup (price: $688) made in Las Vegas with a mere quarter-ounce of the stuff.

"It kills them and then sprouts out of their heads, like a unicorn horn," said lead author Kelly Hopping, an ecologist who conducted the research as a postdoctoral scholar at Stanford's School of Earth, Energy & Environmental Sciences (Stanford Earth).

Beginning in the 1990s, demand for the fungus as an aphrodisiac, impotence cure and remedy for the deadly SARS virus - while unsupported by scientific evidence - helped to jumpstart a global trade. Since then, belief in a wide range of healthful effects from the fungus has fueled a market valued at some $11 billion, as well as concern that harvesting rates have become unsustainable.

Official harvest records are unreliable, however, because much of the caterpillar fungus trade goes through illegal channels. This new study, published in the peer-reviewed Proceedings of the National Academy of Sciences, presents the most comprehensive data to date addressing whether and why caterpillar fungus production might be on the decline, and the likely consequences of a possible crash on the communities that depend on the fungus for their livelihood.

Species and livelihoods under threat

Hopping and study co-author Eric Lambin, a Stanford professor of Earth system science, became interested in the fungus as a way to understand what happens when a niche biological product gives wealthy consumers outsized influence over rural livelihoods, land-use choices and ecosystems in producer regions.

Research on ecosystem degradation tends to focus on the expansion of globally traded agricultural commodities such as oil palm, soy, cattle and timber - the biggest drivers for deforestation. The ripple effects of commodities that grow and trade on a smaller scale are less understood - but potentially profound, Lambin said. He points to rhinoceros horn as an example.

"An emblematic mammal species is being brought to extinction due to the demand for a product which is viewed in some traditional cultures as having virtues," Lambin said.

Caterpillar fungus may lack the charisma of a rhinoceros, but as one of the world's most expensive biological commodities, it has become a primary source of income for hundreds of thousands of collectors. And at a time when up to one-third of the world's parasite species could go extinct within a few decades - potentially opening new niches for other, invasive parasites to exploit - conservation biologists increasingly see a need to protect parasites as well as their hosts.

According to Lambin, who is also a senior fellow at the Stanford Woods Institute for the Environment, there's no question intensive harvesting takes a toll on both people and the environment across an increasingly vulnerable landscape. While many local collectors try to minimize impacts, he said, large influxes of people drawn to the Himalayan rangelands during the peak harvest season can end up degrading ecosystems by disturbing fragile soils, cutting swaths of shrubs and trees for fuel and leaving trash around their harvesting camps.

'Himalayan gold'

Widely known in Tibet as yartsa gunbu, or "summer grass, winter worm," caterpillar fungus has been used in traditional medicine throughout the Himalayan region and in China for centuries to treat ailments ranging from cancer and kidney disease to inflammation and aging. In more recent years it has earned the nicknames "Himalayan Viagra" and "Himalayan gold."

To get around the problem of patchy trade data for the valuable fungus, the team turned to collectors' own knowledge of production trends in China, Bhutan, Nepal and India, as reported in dozens of case studies. The researchers then bolstered the published accounts by interviewing 49 collectors across the Tibetan Plateau.

With this data and 400 records of where the fungus has been found throughout the four countries since the 1970s, the group built models predicting how much fungus would grow in a given area based on factors like climate and elevation. The results show the fungus tends to be more prolific in higher, colder areas around the margins of areas underlain by permafrost.

Warmer winters

Currently, caterpillar fungus is sufficiently abundant in springtime in prime production areas that many people can collect enough in a month or two to support themselves for the rest of the year. However, production is already on the decline due to intensive harvesting - and warming winters may be exacerbating that trend.

In a region where average winter temperatures in some places have already increased by as much as 4 degrees Celsius since 1979 - "an enormous amount of warming," Lambin said - the researchers found that every degree of winter warming makes it makes it harder for the fungus to thrive. As permafrost disappears from lower elevations, the fungus can adapt by shifting to colder upslope habitats only if its caterpillar hosts - and the vegetation and seasonal patterns on which they depend - shift upward, too.

In the long term, if income from caterpillar fungus can be sustained, the study suggests, it could provide an important financial cushion for those whose livelihoods herding livestock on high-altitude grasslands face mounting threats from climate change. "Caterpillar fungus collection has emerged as a way for people in these areas to make relatively easy money," Hopping said, "and in some cases to really raise their standard of living."

However, if demand continues to grow as supplies decrease, it could aggravate tensions over who has access to harvesting areas, Hopping said. "Communities in areas where it's still growing will need to remain vigilant about potential conflicts and poaching as people seek to harvest this increasingly rare and valuable species."

Lambin is also the George and Setsuko Ishiyama Provostial Professor. Hopping is now an assistant professor at Boise State University College of Innovation and Design. Study co-author Stephen Chignell is now a PhD student at the University of British Columbia.
-end-


Stanford's School of Earth, Energy & Environmental Sciences

Related Climate Change Articles:

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).
Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.
Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.
Could climate change cause infertility?
A number of plant and animal species could find it increasingly difficult to reproduce if climate change worsens and global temperatures become more extreme -- a stark warning highlighted by new scientific research.
Predicting climate change
Thomas Crowther, ETH Zurich identifies long-disappeared forests available for restoration across the world.
Historical climate important for soil responses to future climate change
Researchers at Lund University in Sweden, in collaboration with colleagues from the University of Amsterdam, examined how 18 years of drought affect the billions of vital bacteria that are hidden in the soil beneath our feet.
Can forests save us from climate change?
Additional climate benefits through sustainable forest management will be modest and local rather than global.
From crystals to climate: 'Gold standard' timeline links flood basalts to climate change
Princeton geologists used tiny zircon crystals found in volcanic ash to rewrite the timeline for the eruptions of the Columbia River flood basalts, a series of massive lava flows that coincided with an ancient global warming period 16 million years ago.
Think pink for a better view of climate change
A new study says pink noise may be the key to separating out natural climate variability from climate change that is influenced by human activity.
Climate taxes on agriculture could lead to more food insecurity than climate change itself
New IIASA-led research has found that a single climate mitigation scheme applied to all sectors, such as a global carbon tax, could have a serious impact on agriculture and result in far more widespread hunger and food insecurity than the direct impacts of climate change.
More Climate Change News and Climate Change Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.