Vegetable caterpillar

Caterpillar fungus (Cordyceps sinensis) (Tibetan: Yartsa Gunbu [Wylie: dbyar rtswa dgun 'bu, source of  Nepali:यार्सागुम्बा, Yarshagumba, Yarchagumba ) is a  species of parasitic fungus that grows on insect larvae from the genus Thitarodes (formerly Hepialus). It is also known as "keera jhar" in India, but it is known in the West primarily from its use in Chinese medicine. Its name in Chinese (dong chong xia cao 冬虫夏草) means "winter worm, summer grass". The Chinese name is a literal translation of the original Tibetan name, which was first recorded in the 15th Century by the Tibetan doctor Zurkhar Namnyi Dorje (Wylie: Zur mkhar mnyam nyid rdo rje’s [1439-1475]) in his text: Man ngag bye ba ring bsrel (Oral Instructions on a Myriad of Medicines). First mentioning of Cordyceps sinensis in Traditional Chinese Medicine (TCM) was in the 18th Century [In: Wu Yiluo’s “Ben cao cong xin” - “New compilation of materia medica” in 1757]. Often in TCM it is abbreviated as "chong cao", a name that also applies to other Cordyceps species, such as C.militaris.

The caterpillar prone to infection by the fungus lives underground in alpine grass and shrublands on the Tibetan Plateau and the Himalayas at an altitude between 3000m and 5000m. Spending up to five years underground before pupating, the caterpillar is attacked while feeding on roots. The fungus invades the body of the Thitarodes caterpillars, eventually killing and mummifying it. The dark brown to black fruiting body (or mushroom) emerges from the ground in spring or early summer, always growing out of the forehead of the caterpillar. In Nepal caterpillar fungus is found on the subalpine pastures in Dolpo in Karnali zone). It is also common in Bhutan and India's Himachal Pradesh. Reports from distribution outside of High Asia are erroneous and relate to other species of Cordyceps, i.e. Cordyceps militaris.

It is not certain how the fungus infects the caterpillar, possibly by ingesting a fungal spore or by the fungus mycelium invading the insect through one of its breathing pores. Also, the larvae could have a symbiotic relationship with the fungus. Once inside, the fungus mycelium ramifies through the host tissue, eventually completely consuming it and replacing the caterpillar tissue with fungal tissue, while the exoskeletonremains intact. At this stage, the fungus grows a long, usually columnar fruiting body that reaches 5-15 cm above the surface and releases spores. The fungus, sometimes known as tochukaso/tohchukaso, is highly prized by practitioners of Tibetan medicine, Chinese medicine and traditional herbal Folk medicines, in which it is used as an aphrodisiac and as a treatment for a variety of ailments, from fatigue to cancer. It is being regarded as having an excellent balance of yin and yang (through being apparently both animal and vegetable), though it is in actuality not vegetable, but fungal. Assays have found that Cordyceps species produce many pharmacologically active substances. They are now cultivated on an industrial scale for their medicinal value.

The search for Cordyceps sinensis, is often preceived to pose a threat for the Tibetan Plateau where it grows. However, it has been collected for centuries and is still common in such collection areas. Still, current collection rates are much higher than in historical times.

The popularity of this fungus recently grew because two female Chinese athletes, Wang Junxia and Qu Yunxia, who beat the world records for 1500, 3000 and 10000 meters in the early 1980s, used it at the recommendation of their coach; the coach said that this fungus, which has been known for 2000 years, helps athletes. However, it might have been just a nice story to cover up illegal doping or a specific training technique.

Its value gave it a role in the Nepal Civil War, as the Nepalese Maoists and government forces fought for control of the lucrative export trade during the June - July harvest season. Collecting yarchagumba in Nepal had only been legalised in 2001, and now demand is highest in countries such as China, Thailand, Korea and Japan. By 2002, the herb was valued at R 105,000 ($1,435) per kilogram, allowing the government to charge a royalty of R 20,000 ($280) per kilogram.

In Tibet, Yartsa Gunbu developed to the most important source of cash income in rural Tibet. Prices are increasing continuously, especially since the late 1990s. One kg trades in 2007 for US$3000 (lowest quality) to over US$15,000 (best quality = big larvae).