An article on Cordyceps sinensis in Science [Science 322:1182, 21 Nov 2008] reported Chinese entomologist Yang Darong's claim that currently only 3-10% of Cordyceps can be harvested what used to be harvested 20 years ago. This outrageous claim was published without consulting any other researchers on this issue. I wrote a letter to the editor that did not get published. Down below the long version of this letter.
My Reply to Science:
I am very glad to see that Science took up the issue of Yartsa gunbu, summer grass-winter worm, as the Tibetans know Ophiocordyceps / Cordyceps sinensis for at least over 600 years. I am confused why Yang uses the Maori term aweto, which is coined for a New Zealand species. I rather use the Tibetan term Yartsa gunbu, since it also includes the larva and not only the fungus. In addition the Chinese term dongchong xiacao is most likely a literal translation of the original Tibetan term.
I definitely share the concern regarding the sustainability of current Yartsa gunbu harvest intensity. However, Yang Darong's claim that there is only 10% left of this resource is an extraordinary claim and I think we would need to see the data to support such an extraordinary claim. In an earlier South China morning post article Yang was quoted: " Where there used to be 40 specimen per square meter there is now only 5 fungi". That must have been a very special square meter with such a fungal population density! Definitely not the common patch found by many of the Tibetan collectors. Also Yang states, there used to be a production of 1000t per year on the Tibetan Plateau. I really would love to see the base for this figure. At 1000t, mind you, we are talking about roughly 3 billion specimens. At an overall population of 6 million Tibetans on the Plateau, Yang is suggesting a family with 6 members on average needed to collect over 3000 specimens, impossible! To approach this claim from another angle, a 1989 report from the Plateau Biology Research Institute in Lhasa estimated total potential production of about 70t annually for Tibet AR, and reported an average annual harvest of around 13-15t between 1957-1983. TAR provides around 30-50% of the annual production, thus an overall Plateau production total not even close to 100t. In addition, I have interviewed through the years many Tibetan collectors and Tibetan, Chinese and Hui dealers on the Plateau. None of them had reported a substantial reduction in production. All collectors pointed out how they find less caterpillar fungi, but attributed that to the fact that there are so many more collectors. Also, most interviewees pointed out that there are good years and bad years when collecting fungi. Official TAR production figures from 1999 to 2004 indicate an annual harvest between 25 to 50t, the 2006 figure is 38t, nowhere a production crash documented on the scale Yang and his team is claiming.
In trying to make his case of a total resource crash Yang is using the change in value as another indicator. He is stating that 25 years ago he could have traded a bag of salt for a bag of Yartsa gunbu. This reflects much more on the economic situation in China back then than the availability of Yartsa gunbu. Its main consumers are now rich and upper middle class Chinese, a segment of society not in existence in China outside the party structures [the government is still the biggest single buyer of caterpillar fungus in TAR and NW Yunnan. It uses them as presents for visiting officials and as New years presents for its members, a special perk for anybody working in Tibet]. Also, in the 60 and 70s Tibetans had to collect Yartsa gunbu for the government. Per capita quotas had to be filled annually without real payment, which surely ruined the price. Economic reforms only came slowly to the Tibetan areas in the 1980s, but caterpillar fungus prices rose quickly.
Back to the present (= late 2008), this collection season prices peaked, but in recent weeks for the first time in more than a decade Yartsa gunbu prices have decreased substantially. The loss of 20-30% indicates clearly prices were fueled by the coastal economic boom and the availability of discretionary spending rather than reduced harvest level. 2008 was an average harvest and the price decline seems much more connected to the Shanghai stock market crash and the global financial crisis, since Yartsa gunbu has turned from a medicinal tonic into a status symbol in recent years.
I doubt the extent of Yang Darong's extraordinary claim for another reason. Ophiocordycepsand its host, the ghost moth [Thitarodes spp.] are both at the end of their life-cycle. The larva is already killed by the fungus, and the fungus will die off after sporulation. Thus, as long as there are enough spores released, reproduction should be secured. The fact that Yartsa gunbu has been collected for centuries and is still present in areas where intense collection has been carried out suggests that it is a rather resilient organism. A more detailed analysis can be found in Winkler, D. 2008. Yartsa Gunbu (Cordyceps sinensis) and the Fungal Commodification of the Rural Economy in Tibet. In: Economic Botany 62.3.
But we really need long-term fieldwork, something I am sure Yang Darong agrees to. We need to find out if we can come up with harvesting schemes to minimize negative impact an this organism, which has turned into rural Tibet's most important cash source. Some areas derive 80-90% of their cash income from yartsa gunbu. On TAR average it is 40%, contributing more value to the TAR GDP than the industry and mining sector! [ Winkler 2008].
Here the full reference: Stone, R. 2008: Last Stand for the BodySnatcher of the Himalayas? In: Science 322:1182 [21 Nov 2008] www.sciencemag.org