At China鈥檚 1993 National Games in Beijing, Wang Junxia and Qu Yunxia, two unknown women, smashed the world records for 1500, 3000 and 10,000 metres. Their coach, Ma Junren, was besieged by athletes and journalists eager to know how the athletes had achieved such incredible results, which have not been bettered to this day. Their success, he said, was down to the 鈥渞evitalising鈥� properties of a fungus that has been used in Tibetan and Chinese medicine for 2000 years.
Since then, a surge in demand for the fungus has led to environmental damage in the Tibetan plateau where it grows. Yet the fungus鈥檚 biology and its effects on people remain largely unknown.
Each summer, airborne spores of the fungus, Cordyceps sinensis, infect the caterpillars of Thitarodes ghost moths. The caterpillars spend winter underground, feeding on roots. By springtime the fungus has killed the caterpillar and filled its body cavity. It then sends a stalk up, producing new spores to infect the next generation of caterpillars. It is the fungus-stuffed cadaver that is prized by Chinese medicine.
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And demand has ballooned. The SARS outbreak in Hong Kong in 2003 boosted interest further and prices have reached $7000 a kilogram, half that of gold. With so much money to be made, the temptation to over-collect is overwhelming, especially as the fungus is the principal source of income for thousands of villagers in Bhutan and neighbouring countries.
鈥淐aterpillar rush鈥�
In 2002 it is estimated that 2000 kilograms of fungus-infected caterpillars were poached from Bhutan, mainly by collectors crossing the border from Tibet. And in 2003 the harvest tripled. Since each infected caterpillar weighs about 1 gram, the Bhutan trade alone accounts for millions of animals.
Paul Cannon, a biologist at CABI Bioscience in Egham, UK, who has studied the fungus in Jigme Dorji National Park in Bhutan, is concerned about the impact collectors are having to local fauna and flora, including rare medicinal plants. 鈥淓xploitation of the caterpillar is almost certainly unsustainable,鈥� he says. 鈥淩egulation of collection is the most important thing.鈥�
Since 2004 the Bhutanese government has permitted a limited trade in the caterpillar in an attempt to limit the damage, but the 鈥渃aterpillar rush鈥� continues. One option is to farm the caterpillar and its fungus. 鈥淚f they can be reared in captivity, it may be possible for villagers to farm the fungus using local resources,鈥� Cannon says, 鈥渨hich will take a huge pressure off the natural environment.鈥�
