Most of us are familiar with mushrooms that are edible fungi. There are some fungi with medicinal properties too. Some of these fungi are found in the genus Ophiocordyceps, which consists of around 140 species. Among them, Ophiocordyceps sinensis is highly popular for its therapeutic properties, and is used in traditional Chinese and Tibetan medicine.
Most of the fungi in this genus are found in the temperate tropical forests of China, Nepal, Thailand, and some of the neighboring countries. Ophiocordyceps unilateralis is also a species, which is said to have some medicinal properties.
Ophiocordyceps fungi are endoparasitoids, which spend a major part of their life attached to a host. In case of endoparasitoids, they feed on the tissues of the host, and ultimately kill the latter.
Insects are commonly found as the hosts of these fungi. While Ophiocordyceps sinensis attaches itself to the larvae of ghost moths, Ophiocordyceps unilateralis are fond of ants as their hosts.
The spores of this fungus attach themselves to the exoskeleton of the ant's body, and germinate there. Each mycelium enters the ant's body through small pores on the exoskeleton called spiracles, or through the trachea, which are the tubes that enable the ant to breathe.
Once the fungi gain entry into the body of the ant, the mycelia (thin fungal filaments) spread through the whole body cavity, feeding on the soft tissues during the process. The vital organs of the ant's body are not harmed.
Once the fungus gets ready to sporulate, it grows into the brain, and releases certain chemicals that guide the ant to climb up plants. As the ant reaches a spot that is ideal for reproduction of the fungi, it gets attached to the stem or leaves, using their mandibles.
Once settled, the ant gets killed by the fungus, which grows both inside and outside the exoskeleton of the insect. The mycelia that grow outside helps in strengthening the bond between the exoskeleton and the surface to which it is attached.
The fruiting bodies of the fungus grows out of the ant's head and release spores. These spores then attach themselves to other hosts and the life cycle continues.
In short, Ophiocordyceps unilateralis can infect ants and guide them to climb plants and settle at a specific height. Studies show that this is done by the fungi for ensuring the optimum temperature and humidity for release of spores. Such height also ensures maximum spread of the spores.
According to fossil studies, this behavior of Ophiocordyceps unilateralis evolved more than 48 million years ago. The relation between this fungi and ants is one of the nature's ways to check the uncontrolled growth of ant populations.
Even ants can sense the presence of this fungus, and studies show that the infected ants are exiled from the colony, so as to avoid spread of the fungus.
As compared to Ophiocordyceps sinensis, which is widely used in the traditional medicine of China and Nepal, very little is known about the medicinal properties of Ophiocordyceps unilateralis.
However, recent studies show that this fungus contains various beneficial compounds, and studies regarding its medicinal properties are still underway. Some studies suggest that this fungus may be helpful in treating malaria.