1. An introduction to Cordyceps

        The name term 'insect-born fungi' as applied here to the species of Cordyceps originates from the fact that these fungi develop in an insect's body during one summer, remain dormant throughout the winter and then form a plant-like fruiting body during the following spring or summer. These fungi invade insects, kill them, use the nutrients from the host body, and then later form fruiting bodies. The genus Cordyceps belongs to the family Clavicipitaceae of the order Hypocreales (Ascomycota: Pyrenomycetes) and is distributed all over the world including Korea, China and Japan. The reason that they are not better known is because entomologists are not usually actively interested in them and may even intentionally exclude them from study. Mycologists are traditionally more interested in Cordyceps but relatively few mycological taxonomists have chosen to specialize in these entomopathogenic Pyrenomycetes. Much more mycological (and entomological) attention has been paid to the asexual or conidial states of Cordyceps because these fungi are more common, easier to culture and to manipulate, and have a greater potential for applied use in biological control. Nonetheless, insect-born fungi can exert a very real degree of natural control over the density of their host populations and are useful to humans as both for their uses as fungal insecticides and as herbal medicines. An example of the latter use is Cordyceps sinensis in China and Nepal where it is collected from lepidopteran larvae in the Himalayan Mountains at altitudes of 3,000~4,000 m. Since ancient times in China, C. sinensis has been treated as one of three major natural medicines along with ginseng and deer horn. It has been used to treat tuberculosis, jaundice and opium addiction. Lately in Korea and elsewhere, Cordyceps militaris has been found to have anti-cancer effects as well (T. W. Kim, unpublished). Many studies are going on in Korea, China, Japan and elsewhere to determine the other possible benefits of Cordyceps species.

        In this book, insect-born fungi include all Cordyceps species - including those species of Cordyceps and closely related genera that parasitize fungi or the seeds of higher plants - as well as other fungi pathogenic for insects. In mycological terms, the fungi covered here belong to the Ascomycota, Deuteromycota (class Hyphomycetes) or Zygomycota. Some 800 species of entomopathogenic fungi are known, and among these some 300 species are Pyrenomycetes (mainly in the Clavicipitaceae) that form relatively large, visible fruiting bodies. Seventy species of Korean entomopathogens have been collected and are illustrated and discussed here. Some of these fungi show considerable specificity for particular life stages of their hosts, e.g., they may infect only larvae, only pupae, or only adults of a single insect species; these sorts of specificities are noted here, but further studies about the underlying mechanisms for such limitations of development by these fungi deserve further study.

 

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