OPHICORDICEPS UNILATERALIS: CHARACTERISTICS, TAXONOMY, NUTRITION - BIOLOGY - 2025

Ophicordiceps unilateralis is an Ascomycota fungus of the Ophiocordycipitaceae family that parasitizes ants. It develops its mycelium inside the insect without initially killing it, but altering its behavior and when it goes to reproduce, it kills the ant and its fruiting body sprouts through the exoskeleton of the head.

This taxon was originally described by the French botanist and mycologist Louis René Étienne Tulasne in 1865 as Torrubia unilateralis. It is currently considered as a complex of macroscopically very similar species, all of them pathogenic to ants, which are widely distributed throughout the world.

Ophiocordyceps unilateralis fungus feeding on a dead ant. Taken and edited from: This image was created by user walt sturgeon (Mycowalt) at Mushroom Observer, a source for mycological images.You can contact this user here.English - español - français - italiano - македонски - português - +/−.

This fungus produces a series of bioactive substances with medicinal properties, such as naphthoquinone derivatives with antimalarial and antituberculosis potential. It also has metabolites that have shown promising results as immunomodulatory, antitumor and controllers of blood sugar and cholesterol levels.

characteristics

Ophicordiceps unilateralis is an entomopathogenic fungus that parasitizes ants of the genus Camponotus. The fungus grows inside the ant and initially parasitizes it without actually killing it, but modifying its behavior. The ants affected by the fungus are called zombie ants.

The death of the insect occurs near the time of sexual reproduction of the fungus. During this reproduction, a single peduncle emerges from the stroma that breaks the ant's exoskeleton at the nape of the neck. The peduncle has a single ascocarp or perithecia, which is located just below its apex and arranged horizontally.

Taxonomy

Ophiocordyceps unilateralis is an Ascomycota fungus located taxonomically in the class Sordariomycetes, order Hypocreales, and in the family Ophiocordycipitaceae. The genus Ophiocordyceps was erected by the British mycologist Tom Petch in 1931 and currently contains about 140 validly described species, all of them entomopathogenic.

Gender is actually the teleomorphic state, or of sexual reproduction, of various fungi whose anamorphic states have been described as different genera such as Hirsutella, Hymenostilbe, Isaria, Paraisaria and Syngliocladium.

For its part, the species Ophiocordyceps unilateralis was first described for science by Louis René Étienne Tulasne in 1865 as Torrubia unilateralis, and currently mycologists refer to it as Ophiocordyceps unilateralis sensu lato because it really is a complex of species.

Scientists estimate in several hundred the possible species not yet described that could be included in this complex of species and for whose identification macro and microscopic characteristics of their reproductive structures must be used, as well as observations of different aspects of the biology and ecology of the organism.

These aspects to be taken into consideration include, for example, the host species and the effects on it; they also suggest paying particular attention to those populations of Ophiocordyceps unilateralis in which multiple asexual stages (sinanamorphs) have been described.

Reproduction and life cycle

Ophiocordyceps unilateralis is a teleomorphic phase, or of sexual reproduction. When the spores of the fungus find the suitable substrate, that is to say an ant, preferably of the Camponotus leonardi species, they germinate and cross the exoskeleton of the insect, probably secreting enzymes to degrade it.

Once inside the ant, it begins to feed on non-vital tissues while it grows, if it is achieved with another sexually compatible mycelium, they fuse to produce a dicariont mycelium. When the fungus is ready to reproduce, it secretes substances that affect the ant's behavior.

The insect then, which normally does not climb trees, will climb one and attach itself strongly to it using its jaws. The fungus ends up killing the ant, feeding on the rest of its soft tissues and reinforcing the exoskeleton, then it projects some mycelia to the outside of the ant to anchor itself to the substrate.

Finally the sporocarp emerges from the head of the ant. Inside the single ascorcap, the fusion of the nuclei of the reproductive cell (karyogamy) will occur and then the resulting diploid cell meiosis to produce the ascospores that will be released into the environment to restart the cycle.

The fungus also has an asexual (anamorphic) reproduction phase originally identified as Hirsutella formicarum, which reproduces by conidia and can emerge from the ant near the antennae and leg joints.

Camponotus leonardi ant, known as the preferred host for the fungus Ophiocordyceps unilateralis. Taken and edited from: Will Ericson / © AntWeb.org.

Nutrition

Ophiocordyceps unilateralis is a parasitoid. Parasitoids differ from parasites in that the latter do not cause the death of their host, whereas parasitoids do.

The fungus initially feeds on the non-vital soft tissues of the ant, but in order to complete its life cycle it needs to cause the death of its host, then feeding in a saprophytic form on the rest of the previously undigested tissues.

Habitat and distribution

Ophiocordyceps unilateralis is an obligate parasitoid that develops inside ants, mainly of the Camponotus leonardi species, although it can attack ants of other species and even other genera. These ants inhabit tropical forests around the world.

According to some authors, Ophiocordyceps unilateralis lives in the tropical forests of Thailand and Brazil, however other authors maintain that it is a cosmopolitan species.

As long as taxonomists do not clarify which are the different species that make up the Ophiocordyceps unilateralis complex, it is impossible to know the real distribution of the species in its strict sense.

Medical and industrial importance

Ophiocordyceps unilateralis produces a significant amount of metabolites with potentially useful properties for medicine, including substances capable of modulating the immune system, other antitumor, anticancer and antibiotic substances.

It can also control the levels of sugar and cholesterol in the blood, avoiding the appearance of various diseases, such as diabetes or arteriosclerosis.

Derivatives of naphthoquinone isolated from Ophiocordyceps unilateralis have shown antimalarial activity similar to that shown by other known drugs. These derivatives include, for example, erythrostominone and deoxyieritrostominone.

Researchers have noted that the bioactives produced by O. unilateralis are also potential candidates in tuberculosis-related research.

Lastly, studies have been conducted for the use of naphthoquinone red pigments synthesized by Ophiocordyceps unilateralis in cosmetology, food industry and also in pharmacology.

References

1. S. Mongkolsamrit, N. Kobmoo, K. Tasanathai, A. Khonsanit, W. Noisripoom, P. Srikitikulchai, R. Somnuk & JJ Luangsa-ard (2012). Life cycle, host range and temporal variation of Ophiocordyceps unilateralis / Hirsutella formicarum on Formicine ants. Journal of Invertebrate Pathology.
2. HC Evans, SL Elliot & DP Hughes (2011). Hidden diversity behind the zombie-ant fungus Ophiocordyceps unilateralis: Four new species described from carpenter ants in Minas Gerais, Brazil. PLoS ONE.
3. HC Evans, SL Elliot & DP Hughes (2011). Ophiocordyceps unilateralis. A keystone species for unraveling ecosystem functioning and biodiversity of fungi in tropical forests? Communicative & Integrative Biology.
4. Ophiocordyceps. On Wikipedia. Recovered from: en.wikipedia.org.
5. Ophiocordyceps unilateralis. On Wikipedia. Recovered from: en.wikipedia.org.
6. P. Kittakoopa, J. Punyaa, P. Kongsaeree, Y. Lertwerawat, A. Jintasirikul, M. Tanticharoena & Y. Thebtaranonth (1999). Bioactive naphthoquinones from Cordyceps unilateralis. Phytochemistry.