Graveyards on the move

The spatio-temporal distribution of dead ophiocordyceps-infected ants

Maj Britt Pontoppidan, Winanda Himaman, Nigel L. Hywel-Jones, Jacobus J. Boomsma, David Peter Hughes

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

Parasites are likely to play an important role in structuring host populations. Many adaptively manipulate host behaviour, so that the extended phenotypes of these parasites and their distributions in space and time are potentially important ecological variables. The fungus Ophiocordyceps unilateralis, which is pan-tropical in distribution, causes infected worker ants to leave their nest and die under leaves in the understory of tropical rainforests. Working in a forest dynamic plot in Southern Thailand we mapped the occurrence of these dead ants by examining every leaf in 1,360 m2 of primary rainforest. We established that high density aggregations exist (up to 26 dead ants/m2), which we coined graveyards. We further established that graveyards are patchily distributed in a landscape with no or very few O. unilateralis-killed ants. At some, but not all, spatial scales of analysis the density of dead ants correlated with temperature, humidity and vegetation cover. Remarkably, having found 2243 dead ants inside graveyards we only found 2 live ants of the principal host, ant Camponotus leonardi, suggesting that foraging host ants actively avoid graveyards. We discovered that the principal host ant builds nests in high canopy and its trails only occasionally descend to the forest floor where infection occurs. We advance the hypothesis that rare descents may be a function of limited canopy access to tree crowns and that resource profitability of such trees is potentially traded off against the risk of losing workers due to infection when forest floor trails are the only access routes. Our work underscores the need for an integrative approach that recognises multiple facets of parasitism, such as their extended phenotypes.

Original languageEnglish (US)
Article numbere4835
JournalPloS one
Volume4
Issue number3
DOIs
StatePublished - Mar 12 2009

Fingerprint

Ophiocordyceps
Cemeteries
Ants
Formicidae
Fungi
Atmospheric humidity
Profitability
Agglomeration
forest litter
multiparasitism
canopy
Parasites
phenotype
parasites
Camponotus
Temperature
ant nests
tropical rain forests
Phenotype
vegetation cover

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

Pontoppidan, Maj Britt ; Himaman, Winanda ; Hywel-Jones, Nigel L. ; Boomsma, Jacobus J. ; Hughes, David Peter. / Graveyards on the move : The spatio-temporal distribution of dead ophiocordyceps-infected ants. In: PloS one. 2009 ; Vol. 4, No. 3.
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Graveyards on the move : The spatio-temporal distribution of dead ophiocordyceps-infected ants. / Pontoppidan, Maj Britt; Himaman, Winanda; Hywel-Jones, Nigel L.; Boomsma, Jacobus J.; Hughes, David Peter.

In: PloS one, Vol. 4, No. 3, e4835, 12.03.2009.

Research output: Contribution to journalArticle

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