Cordyceps
Introduction
Cordyceps is a genus of fungi that includes approximately 400 recorded species of parasitic fungi [1]. Cordyceps belong to the ascomycota phylum, also known as “sac fungi” [2].They produce microscopic sexual structures where non-motile spores are formed [3]. The hosts of these fungi include various arthropods, including insects- often in larvae form-spiders, mites and other fungi [4]. Cordyceps are known for their ability to manipulate their hosts for their own survival and reproductive purposes [3].
Cordycep fungi are distributed worldwide, but particularly in Asian countries, including Tibet, Thailand, and China— in places where the climate is humid and warm [5]. They were also used traditionally as medicine, notably in Tibet and China, and are currently being researched for medicinal uses [6].
Metabolism, Nutrient Requirements and Distribution
Cordycep produce proteases and chitinases that degrade the cuticles of insect hosts in preparation for invasion [3]. They grow osmotrophically: they secrete enzymes to degrade external substrates,and then absorb the resulting sugars and amino acids [3]. A qPCR assay quantifying the biomass of Ophiocordyceps sinensis in Thitarodes larvae found that they aggregated the most in these tissues in order of decreasing density: fat body, body wall, haemolymph and intestinal walls [7].The fat body is the primary region of parasitism because of the energy it can provide in metabolism; additionally, the next generation of the fungus could be transmitted to the ovaries through this region [7]. Orange colored extensions of the fungi are found in the abdominal areas of ant hosts, and extend to the base of the stroma [3]. This structure is rich in carbon compared to the white and black colored hyphae, probably due to specialization of the different fungal structures, where the orange hyphae are for carbon storage [3]. The fruiting body stores unsaturated fatty acids [8]. With their array of enzymes and unique structures, Cordyceps have evolved to effectively degrade their specific hosts, and acquired organized division of the nutrients absorbed and synthesized.
