{{Taxobox
| image = Ophiocordyceps unilateralis.png
| image_width = 240px
| image_caption = Dead ants infected with ''Ophiocordyceps unilateralis''
| regnum = [[Fungus|Fungi]]
| divisio = [[Ascomycota]]
| classis = [[Sordariomycetes]]
| ordo = [[Hypocreales]]
| familia = [[Ophiocordycipitaceae]]
| genus = ''[[Ophiocordyceps]]''
| species = '''''O. unilateralis'''''
| binomial = ''Ophiocordyceps unilateralis''
| binomial_authority = ([[Tul.]]) [[Tom Petch|Petch]] (1931)
| synonyms_ref = <ref name=MBank/>
| synonyms = ''Torrubia unilateralis'' <small>Tul. (1865)</small><br>
''Cordyceps unilateralis'' <small>(Tul.) [[Sacc.]] (1883)</small>
}}
'''''Ophiocordyceps unilateralis''''' is a [[parasitoid]]al [[fungus]] that infects [[ant]]s such as ''[[Camponotus leonardi]]'' and alters their behavior. The ant falls from the tree where it normally lives, climbs on the stem of a plant, clamps its [[mandible (insect mouthpart)|mandibles]] on a leaf and dies there, while the fungus consumes its tissues and grows outside it, releasing its [[spore]]s.  The infected ants are popularly known as '''zombie ants'''.<ref name=Amore/> This is a prime example of a parasitoid that alters the behavior of its host in order to ensure its own reproduction.<ref name=neup/>

== Morphology ==
The species can be identified at the end of its lifecycle by its reproductive structure, consisting of a wiry yet pliant darkly pigmented [[stroma (mycology)|stroma]] stalk extending from the back of the deceased ant's head. The stalk has [[perithecia]] just below its tip.<ref name=ponto/><ref name=sung/>
== Life cycle ==

Like other [[entomopathogenic fungus|fungi pathogenic to insects]] in the ''[[Ophiocordyceps]]'' genus, ''O. unilateralis'' targets a specific host species, the ''Camponotus leonardi'' ant.  However the fungus may parasitize other closely related species of ants with lesser degrees of host manipulation and reproductive success.<ref name=neup/>

The fungus's spores enter the body of the insect likely through the cuticle by enzymatic activity, where they begin to consume the non-vital soft tissues. Yeast stages of the fungus spread in the ant's body and presumably produce compounds that affect the ant's brain and change its behaviour by unknown mechanisms. The insect climbs up the stem of a plant and uses its mandibles to secure itself to a leaf vein, with abnormal force, leaving [[dumbbell]]-shaped marks on it. A search through plant fossil databases revealed similar marks on a fossil leaf from the [[Messel pit]] which is 48 million years old.<ref name=Zombie/><ref name=Hughes/>

The fungus then kills the ant, and continues to grow as its hyphae invade more soft tissues and structurally fortify the ant's exoskeleton.<ref name=neup/> More mycelia then sprout out of the ant, and securely anchor it to the plant substrate while secreting antimicrobials to ward off competition.<ref name=neup/> When the fungus is ready to reproduce, its [[fruiting bodies]] grow from the ant's head and rupture, releasing the spores. This process takes 4 to 10 days.<ref name=neup/>

The changes in the behavior of the infected ants are very specific, giving rise to the popular term "zombie ants", and tuned for the benefit of the fungus. The ants suffer from convulsions causing them to fall to the ground and preventing them from finding their way back to their canopy.<ref name=FuBrain/>  The ants generally clamp to a leaf's vein about 25&nbsp;cm above the ground, on the northern side of the plant, in an environment with 94-95% humidity and temperatures between 20 and 30&nbsp;°C. According to David Hughes, "You can find whole graveyards with 20 or 30 ants in a square metre. Each time, they are on leaves that are a particular height off the ground and they have bitten into the main vein [of a leaf] before dying".<ref name=GU/> When the dead ants are moved to other places and positions, further vegetative growth and sporulation either fails to occur or results in undersized and abnormal reproductive structures.<ref name=Andersen/>

== Geographic distribution ==
The fungus occurs in tropical forests throughout the world, including those in [[Africa]], [[Brazil]] and [[Thailand]].<ref name=Harmon/>

== Host impact ==
''O. unilateralis'' has been known to destroy entire ant colonies.  In response, ants have evolved the ability to sense that a member of the colony is infected; healthy ants will carry the dying one far away from the colony in order to avoid fungal spore exposure.<ref name=ponto/><ref name=sung/>

==Medicinal potential==
The Ophiocordyceps fungus contains various known and untapped bioactive metabolites, and is being investigated as a new source of natural drugs with immunomodulatory, antitumor, hypoglycemic and hypocholesterolemic functions.<ref name=Xiao/>

Six bioactive [[naphthoquinone]] derivatives have been isolated from ''O. unilateralis'', namely 
* [[erythrostominone]]
* [[deoxyerythrostominone]]
* 4-O-methyl erythrostominone|4-''O''-methyl erythrostominone
* [[epierythrostominol]]
* [[deoxyerythrostominol]], and
* 3,5,8-trihydroxy-6-methoxy-2-(5-oxohexa-1,3-dienyl)-1,4-naphthoquinone showed [[antimalarial drug|anti-malarial]] activity [[in vitro]].<ref name=Kittakoopa/><ref name=Wongsa/>

There has also been research into the use of red naphthoquinone pigments made by ''O. unilateralis'' as a dye for food, cosmetic and pharmaceutical manufacturing processes.<ref name=Unagul/>

==See also==
* [[Behavior-altering parasites and parasitoids]]

==External links==
* [http://beta.uniprot.org/taxonomy/268505 Ophiocordyceps unilateralis] at [[UniProt]].org. Accessed on 2010-08-22.
* [http://cordyceps.us An Electronic Monograph of Cordyceps and Related Fungi]

==References==
<references>

<ref name=neup>
  Ian Sample (2010), [http://www.sw-gm.com/index.php?t=5987 "Parasitic mind control fungus exists for 48m years"]. 18 August 2010, at Parascientifica.com
</ref>

<ref name=ponto>
  M. B. Pontoppidan, W. Himaman, N. L. Hywel-Jones, J. J. Boomsma, D. P. Hughes (2009), "Graveyards on the move: The spatio-temporal distribution of dead ''Ophiocordyceps''-infected ants". PLoS ONE, volume 4, issue 3, pages e4835. {{doi|10.1371/journal.pone.0004835}} PMID 19279680.
</ref>

<ref name=sung>
  G. H. Sung, N. L. Hywel-Jones, J. M. Sung, J. J. Luangsa-Ard, B. Shrestha, and others (2007). "Phylogenetic classification of ''Cordyceps'' and the clavicipitaceous fungi". Studies in Mycology, volume 57, pages 5-59, {{doi|10.3114/sim.2007.57.01}}, PMID 18490993
</ref>

<ref name=Zombie>
  (2010) [http://www.sciencedaily.com/releases/2010/08/100818105730.htm "Fossil Reveals 48-Million-Year History of Zombie Ants"] Science Daily (online), 18 August 2010. Acessed on 2010-09-12
</ref>

<ref name=MBank>
  [http://www.mycobank.org/MycoTaxo.aspx?Link=T&Rec=281145 "''Ophiocordyceps unilateralis'' (Tul.) Petch 1931"] at MycoBank. International Mycological Association. Accessed on 2011-07-19
</ref>

<ref name=Hughes>
  David P. Hughes, Torsten Wappler, Conrad C. Labandeira (2010), "Ancient death-grip leaf scars reveal ant fungal parasitism". Biology Letters of The Royal Society, volume 7, issue 1, pages 67-70. {{doi|10.1098/rsbl.2010.0521} PMID 20719770
</ref>

<ref name=GU>
  Ian Sample (2010), [//www.guardian.co.uk/science/2010/aug/18/zombie-carpenter-ant-fungus "'Zombie ants' controlled by parasitic fungus for 48m years"]. The Guardian (online), 18 August 2010. Accessed on 2010-08-22
</ref>

<ref name=Andersen>
  S. B. Andersen, S. Gerritsma, K. M. Yusah, D. Mayntz, N. L. Hywel-Jones, J. Billen, J. J. Boomsma, D. P. Hughes (2009), "The life of a dead ant: The expression of an adaptive extended phenotype". The American Naturalist, volume 174, issue 3, pages 424-433  {{doi|10.1086/603640}}, PMID 19627240
</ref>

<ref name=Harmon>
  Katherine Harmon (2009) [http://www.scientificamerican.com/article.cfm?id=fungus-makes-zombie-ants "Fungus makes zombie ants do all the work"]. Scientific American (online), 31 July 2009. Accessed on 2010-08-22.
</ref>

<ref name=Amore>
  Christine Dell'Amore (2012), [http://news.nationalgeographic.com/news/2012/05/120504-zombie-ant-fungus-science-environment-rainforest/ "'Zombie Ant' fungus under attack"]. National Geographic (online). Accessed on 2012-11-28.
</ref> 

<ref name=Xiao>
  J. H. Xiao, J. J. Zhong (2007), "Secondary metabolites from ''Cordyceps'' species and their antitumor activity studies". Recent Patents on Biotechnology, volume 1, issue 2, pages 123-137. {{doi|10.2174/187220807780809454}} PMID 19075836
</ref>

<ref name=Wongsa>
  P. Wongsa, K. Tasanatai, P. Watts, N. Hywel-Jones (2005) "Isolation and in vitro cultivation of the insect pathogenic fungus ''Cordyceps unilateralis''". Mycological Research, volume 109, issue Pt 8, pages 936-940. {{doi|10.1017/S0953756205003321}} PMID 16175796
</ref>

<ref name=Unagul>
  P. Unagul, P. Wongsa, P. Kittakoop, S. Intamas, P. Srikitikulchai, and M. Tanticharoen (2005), "Production of red pigments by the insect pathogenic fungus ''Cordyceps unilateralis''". Journal of Industrial Microbiology & Biotechnology, volume 32, issue 4, pages 135-140. {{doi|10.1007/s10295-005-0213-6}} PMID 15891934
</ref>

<ref name=Kittakoopa>
  P. Kittakoopa, J. Punyaa, P. Kongsaeree, Y. Lertwerawat, A. Jintasirikul, M. Tanticharoena, and Y. Thebtaranonth (1999), "Bioactive naphthoquinones from ''Cordyceps unilateralis''". Phytochemistry, volume 52, issue 3, pages 453-457. {{doi|10.1016/S0031-9422(99)00272-1}}
</ref>

<ref name=FuBrain>
  (2011), [http://www.sciencedaily.com/releases/2011/05/110509065536.htm "Zombie Ants have fungus on the brain, new research reveals"]. Science Daily. Accessed on 2012-11-27.
</ref>

</references>

{{DEFAULTSORT:Ophiocordyceps Unilateralis}}
[[Category:Fungi described in 1865]]
[[Category:Fungi of Africa]]
[[Category:Fungi of Asia]]
[[Category:Fungi of South America]]
[[Category:Hypocreales]]
[[Category:Mind-altering parasites]]
[[Category:Parasitic fungi]]

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