Locality: Bhutan (27.332740, 90.439450)

Abstract: As many as 100 species of insect fungi (relatives of Yartsa Goenbub - Ophiocordyceps sinensis) have been recorded from Bhutan. More than 85 species have been named while there are several new species that remain to be described. The following descriptions provide a brief introduction to the insect fungi of Bhutan. Yartsa Goenbub is the most famous insect fungus in Bhutan because of the high price it fetches and the income it generates for countless households in the mountains close to the Tibetan border. However, it is only one species amongst several hundred species of fungi that infect and kill insects around the World. Most fungi infect plants or grow on dead plant material. But the insect fungi have evolved to infect and grow inside insect hosts. They slowly deplete the insect of the nutrients it needs to grow. Eventually, the fungus (e.g. Yartsa Goenbub) will kill its insect host and then grow out to produce spores that can then infect the next generation of insects. Most of the insect fungi have developed a very close relationship with their hosts. They will be tied to the life-cycle of that insect and often infect only a particular stage in the insect's life-cycle. Yartsa Goenbub is an example of this group. It infects only the caterpillar – not the eggs, pupae or adults. However, there are some species that have evolved so that they can infect a wide range of insects and at any stage of the life-cycle. The most common of these are Beauveria bassiana and Metarhizium anisopliae. In any agricultural system around the world these two species can be found killing insect pests. As such, they are considered to be 'friendly fungi'. But it was not always the case. Beauveria bassiana first came to the attention of scientists in the early nineteenth century when it was far from 'friendly'. It had become a serious problem in the French and Italian silkworm industry where it was killing the silkworms in large numbers. Although the Frenchman Louis Pasteur is credited with the 'Germ Theory' it was really an Italian – Agostino Bassi – who did the pioneering work some thirty years before Pasteur. Bassi was able to demonstrate that taking the white spores of Beauveria bassiana and dusting them on to otherwise healthy silkworms this would lead to the death of those worms. To honour Bassi, the fungus was named after him – Beauveria bassiana.

Over the last one hundred years or so, both Beauveria bassiana and Metarhizium anisopliae have been investigated as potential biological control agents of insect pests. A few other species that can be grown easily in culture have also been tested as potential biocontrol agents. There is still much research that needs to be done and currently there are few, if any, successful commercial biocontrol agents based on insect fungi. While Yartsa Goenbub has a long history of usage in traditional Asian medicine it is only recently that it has attracted attention around the World. A close relative of Yartsa Goenbub is used in New Zealand by Maori people as a dye for their tattoos. Another species, Cordyceps militaris is also used in Chinese, Korean and Japanese traditional medicine. More recently, these fungi have also been investigated for novel metabolites that may be of benefit to man – chiefly pharmaceutical agents such as antibiotics and anti-cancer compounds

The following descriptions provide a brief introduction to the insect fungi of Bhutan.

References:
Mata, Miagro, Dawa Penjor and Sabitra Pradhan. 2010. Fungi of Bhutan. National Mushroom Centre, Ministry of Agriculture and Forests, Thimphu, Bhutan. p. 316.

Notes: Project supported by the United States Fulbright Scholar Program, Washington, D.C. (2017). The Fulbright Program is the flagship international educational exchange program sponsored by the U.S. government.