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Symbiotic fungal endophytes control insect host–parasite interaction webs

Nature volume 409, pages 7881 (04 January 2001) | Download Citation

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Abstract

Symbiotic microorganisms that live intimately associated with terrestrial plants affect both the quantity and quality of resources1,2, and thus the energy supply to consumer populations at higher levels in the food chain. Empirical evidence on resource limitation of food webs points to primary productivity as a major determinant of consumer abundance and trophic structure3,4,5,6. Prey quality plays a critical role in community regulation7,8. Plants infected by endophytic fungi are known to be chemically protected against herbivore consumption9,10,11. However, the influence of this microbe–plant association on multi-trophic interactions remains largely unexplored. Here we present the effects of fungal endophytes on insect food webs that reflect limited energy transfer to consumers as a result of low plant quality, rather than low productivity. Herbivore–parasite webs on endophyte-free grasses show enhanced insect abundance at alternate trophic levels, higher rates of parasitism, and increased dominance by a few trophic links. These results mirror predicted effects of increased productivity on food-web dynamics12. Thus ‘hidden’ microbial symbionts can have community-wide impacts on the pattern and strength of resource–consumer interactions.

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Acknowledgements

We thank A. Austin, M. Bonsall, A. Bourke, C. Godfray, D. Golombek, T. H. Jones, N. Mazía, R. Pettifor, S. Power, P. Roset, S. Semple and M. Vila-Aiub for comments on the manuscript; E. Demartin, P. Gundel and M. Rabadan for field assistance; R. Belshaw and F. van Veen for helping with parasitoid identification; and C. Godfray for constructing the web diagrams. This study was funded by grants from the Agencia Nacional de Promoción Cientifica y Tecnológica of Argentina and Fundación Antorchas.

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Affiliations

  1. *IFEVA-Departamento de Recursos Naturales y Ambiente, Facultad de Agronomia, Universidad de Buenos Aires, Av. San Martin 4453, 1417 Buenos Aires, Argentina

    • Marina Omacini
    • , Enrique J. Chaneton
    •  & Claudio M. Ghersa
  2. †Department of Biology and NERC Centre for Population Biology, Imperial College at Silwood Park, Ascot, Berkshire SL5 7PY, UK

    • Christine B. Müller
  3. ‡The Zoological Society of London, Institute of Zoology, Regent's Park, London NW1 4RY, UK

    • Christine B. Müller

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Correspondence to Marina Omacini or Christine B. Müller.

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https://doi.org/10.1038/35051070

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