Himalayan Viagra is under threat

A parasitic fungus that is more valuable than gold, and is nicknamed "Himalayan Viagra" due to its demand as an impotence cure, could vanish if current harvesting and climate trends continue, according to a study using data from four countries, including India.

The fungus survives by preying on ghost moth caterpillars in some of the highest reaches of the Himalayas, said researchers from the Stanford University in the US.

The fungus infects and eats the insides of a caterpillar that burrows underground for winter, said Kelly Hopping, who conducted the research as a postdoctoral scholar at Stanford.

Beginning in the 90s, 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, researchers said.

Since then, belief in a wide range of healthful effects from the fungus has fuelled a market valued at some

USD 11 billion, as well as concern that harvesting rates have become unsustainable.

As one of the world's most expensive biological commodities, caterpillar fungus has become a primary source of income for hundreds of thousands of collectors. It 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 ageing.

In more recent years it has earned the nicknames "Himalayan Viagra" and "Himalayan gold," researchers said.

Recent results show the fungus tends to be more prolific in higher, colder areas around the margins of areas underlain by permafrost.

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, researchers said. However, production is already on the decline due to intensive harvesting -- and warming winters may be exacerbating that trend, they said.