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Caterpillars and fungal pathogens: two co-occurring parasites of an ant-plant mutualism

Roux, Olivier and Céréghino, Régis and Solano, Pascal J. and Dejean, Alain Caterpillars and fungal pathogens: two co-occurring parasites of an ant-plant mutualism. (2011) PLoS ONE, 6 (5). 1-8. ISSN 1932-6203

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Official URL: http://dx.doi.org/10.1371/journal.pone.0020538


In mutualisms, each interacting species obtains resources from its partner that it would obtain less efficiently if alone, and so derives a net fitness benefit. In exchange for shelter (domatia) and food, mutualistic plant-ants protect their host myrmecophytes from herbivores, encroaching vines and fungal pathogens. Although selective filters enable myrmecophytes to host those ant species most favorable to their fitness, some insects can by-pass these filters, exploiting the rewards supplied whilst providing nothing in return. This is the case in French Guiana for Cecropia obtusa (Cecropiaceae) as Pseudocabima guianalis caterpillars (Lepidoptera, Pyralidae) can colonize saplings before the installation of their mutualistic Azteca ants. The caterpillars shelter in the domatia and feed on food bodies (FBs) whose production increases as a result. They delay colonization by ants by weaving a silk shield above the youngest trichilium, where the FBs are produced, blocking access to them. This probable temporal priority effect also allows female moths to lay new eggs on trees that already shelter caterpillars, and so to occupy the niche longer and exploit Cecropia resources before colonization by ants. However, once incipient ant colonies are able to develop, they prevent further colonization by the caterpillars. Although no higher herbivory rates were noted, these caterpillars are ineffective in protecting their host trees from a pathogenic fungus, Fusarium moniliforme (Deuteromycetes), that develops on the trichilium in the absence of mutualistic ants. Therefore, the Cecropia treelets can be parasitized by two often overlooked species: the caterpillars that shelter in the domatia and feed on FBs, delaying colonization by mutualistic ants, and the fungal pathogen that develops on old trichilia. The cost of greater FB production plus the presence of the pathogenic fungus likely affect tree growth.

Item Type:Article
Additional Information:Thanks to Public Library of Science editor. The definitive version is available at http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0020538
HAL Id:hal-00912399
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:Other partners > AgroParisTech (FRANCE)
French research institutions > Centre de Coopération Internationale en Recherche Agronomique - CIRAD (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Other partners > Pascal Solano (FRANCE)
Other partners > Université des Antilles et de la Guyane (FRANCE)
Laboratory name:
Deposited On:02 Dec 2013 09:00

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