Harvesting of a parasitic fungus that grows high on the Tibetan Plateau in China is infusing hordes of cash into rural communities, scientists say.
The fungus, Ophiocordyceps sinensis, takes over the bodies of caterpillar larvae then shoots up like finger-size blades of grass out of the dead insects' heads. (See related pictures: "'Zombie' Ants Found With New Mind-Control Fungi.")
Known as yartsa gunbu—or "summer grass winter worm"—by Chinese consumers, the nutty-tasting fungus is highly valued for its purported medicinal benefits, for instance, as a treatment for cancer and aging and as a libido booster. Far away in the booming cities of Beijing and Shanghai, demand for the fungus has soared.
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"Medically, it seems to deliver," according to Daniel Winkler, a fungus researcher and head of Eco-Montane Consulting in Seattle, Washington.
"Even the whole thing that it's an aphrodisiac—yes, it might really help."
Some Chinese grind up the fungus and sell it as a powder, and others use it whole as a garnish—and therefore a display of wealth.
"When you want to impress your business partner, you stuff some kind of fowl with it to show that money doesn't really matter to you, because you just stuffed your goose with $100 worth of mushrooms," Winkler said.
In Tibet (see map) and other Himalaya regions of Nepal and Bhutan, yak herders who harvest the fungus are getting rich from fungus sales.
By one account, the value of caterpillar fungus shot up 900 percent between 1997 and 2008, said Winkler, who has studied the phenomenon.
Nomadic yak herders now ride motorcycles, own apartments in the city, send their kids to schools, and pay someone else to do their village chores, he said.
In Search of Fungal Gold
To keep up with demand, rural harvesters spend about four weeks each spring stooped over on grassy slopes, pick axes in hand, searching for fungal gold.
Harvesters pluck the package—caterpillar larva and parasitic fungus—whole from the ground. Over the course of a month, a prolific harvester can earn more than enough cash to live on for an entire year. In rural Tibet, the fungus accounts for at least 40 percent of people's cash income.
In Yunnan Province, caterpillar fungus sales account for 60 to 80 percent of annual household cash income, which is used to pay for school, food, refrigerators, motorbikes, and livestock, according to Michelle Olsgard Stewart, a doctoral student in geography at the University of Colorado at Boulder.
The surge in value of the fungus has also prompted more people to participate in the annual harvest, said Stewart, who is researching the fungus.
"Households will now send three to five individuals up to harvest, whereas in the past they might have sent one to two," she said.
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Fungus Harvests Spark Deadly Disputes
In some parts of the fungus' range, such as China's Qinghai Province, disputes over access to pastures where the species grows turn lethal each year—a sign of the economic importance the fungus now holds, Stewart notes.
The disputes tend to erupt where rights to traditional grazing lands are fuzzy or where the government steps in and sells permits to outsiders.
For example, in July 2007, eight people were shot to death in a gun battle over prime fungal turf in Yushu, close to the border with Tibet, the Guardian newspaper reported.
In Yunnan Province, where Stewart works, there haven't been any deadly conflicts, perhaps because "they seem to have pretty clear rules over who can access which harvest areas," she said.
Given the value of the fungus, Eco-Montane's Winkler noted it's remarkable how few people get killed in conflicts over its harvest.
In markets where the fungus is bought and sold, traders routinely walk around with bags full of several thousand dollars' worth of the product. "You couldn't do that in the U.S.," he said.
Caterpillar Fungus Still Plentiful
Though the scientists are concerned the fungus will be overharvested, data collected so far suggests it's still plentiful.
"I went into this thinking, Wow, people are really going to start noticing this huge decline," Stewart said. "I really haven't seen that response in harvests yet."
The number of fungi picked per person has dropped, but buyers told Stewart that they haven't noticed a decline in yartsa gunbu available for purchase.
These observations fit with Winkler's data, which show that enough fungi are left in the ground to release spores, which invade the next generation of caterpillar larvae.
"The larvae is apparently not really impacted by the collection, and the fungus still seems to get enough spores out," said Winkler, who published a study about fungus harvesting in 2010 in the international version of the German journal Geographische Rundschau.
Hints of a fungus decline surfaced in 2008, when Yang Darong, an ecologist at the Chinese Academy of Sciences, circulated a report suggesting caterpillar fungus had declined to just 3 to 10 percent of its numbers 20 years prior.
Winkler noted that Darong's report lacks baseline data from field plots or government figures to support its conclusions. (Darong did not respond to a request for an interview.)
But Winkler and others want to obtain their own data on the fungus' presence so that they can begin to address questions about the sustainability of the harvest—especially given its new role in the market economy on the Tibetan Plateau.
Even without a lot of hard data, "one has to be totally worried about [the harvest's] intensity," Winkler said. "How long can you keep it up on that level?"
For the time being, Winkler is proposing a plateau-wide harvest season, which he plans to pitch this spring on a research trip to Tibet.
His idea is to encourage harvesters to stop picking as the fungi reach maturity, leaving enough in the ground to spread their spores.
But when he talks to the collectors, "I'm prepared to hear that there is nothing to worry about."
(See "Lightning Makes Mushrooms Multiply.")
Fungus Collapse Wouldn't Devastate Herders
Should a collapse occur, Winkler and Stewart fear the consequences could be devastating for the herders' economy. While other sources of cash income such as construction and mining are available in the region, nothing is nearly as lucrative as caterpillar fungus.
To Stewart, the prospect of a crash in the caterpillar-fungus trade is worrying, but she thinks a decline would instead be gradual enough for communities to adapt without completely losing their ties to the market economy.
"It's important to realize that it's not a binary event—you have it or you don't," she said.
"There would likely be gradual changes over time. And even if the market prices dropped significantly, there would still be some. So there would be a slow transition, not a point where harvesters have to suddenly find another form of income."
This report was made possible with funding from The Christensen Fund.