Washington: A prized caterpillar fungus that is more valuable than gold and is nicknamed "Himalayan Viagra" in Asia, where it is seen as a wonder drug, is becoming harder to find due to climate change, researchers said on Monday. People in China and Nepal have been killed in clashes over the years over the elusive fungus "yarchagumba," known formally as Ophiocordyceps sinensis.
Although it has no scientifically proven benefits, people who boil yarchagumba in water to make tea or add it to soups and stews believe it cures everything from impotence to cancer.
It is "one of the world's most valuable biological commodities, providing a crucial source of income for hundreds of thousands of collectors," said the report in the Proceedings of the National Academy of Sciences, a peer-reviewed US journal.
In recent decades, the fungus has skyrocketed in popularity and prices have soared -- it can fetch up to three times the price of gold in Beijing, researchers say. While many have suspected overharvesting was the reason for its scarcity, researchers wanted to find out more. So they interviewed around four dozen harvesters, collectors and traders of the prized fungus.
They also examined previously published scientific literature, including interviews with more than 800 people in Nepal, Bhutan, India and China, in order to understand its apparent decline. Weather patterns, geographic factors and environmental conditions were also analysed to create a map of yarchagumba production in the region.
"Using data spanning nearly two decades and four countries, (we) revealed that caterpillar fungus production is declining throughout much of its range," said the report.
The finding "is important because it calls attention to how highly valuable species, like caterpillar fungus, are susceptible not only to overharvesting, as is often the focus, but also to climate change," lead study author Kelly Hopping told AFP.
"This means that even if people start reducing the amount that they harvest, production will likely continue to dwindle as a result of ongoing climate change," said Hopping, who conducted the work while a postdoctoral research fellow at Stanford University and is currently assistant professor in Human-Environment Systems at Boise State University.
Researchers were unable to tell which factor -- overharvesting or climate change -- had a larger impact on the fungus.
"To do so would require access to better harvest records, but monitoring of it is very limited throughout most of the areas where it grows," Hopping said.