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Understanding biodiversity effects on prey in multi-enemy systems

Authors

  • Paolo Casula,

    Corresponding author
    1. Centre for Population Biology, Division of Biology, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK
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  • Andrew Wilby,

    1. Centre for Agri-Environmental Research, Department of Agriculture, University of Reading, Reading, Berks RG6 6AR, UK
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  • Matthew B. Thomas

    1. Centre for Population Biology, Division of Biology, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK
    2. CSIRO Entomology, GPO Box 1700, Canberra ACT 2601, Australia
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E-mail: paolocasula@tiscali.it

Abstract

Biodiversity–ecosystem functioning theory would predict that increasing natural enemy richness should enhance prey consumption rate due to functional complementarity of enemy species. However, several studies show that ecological interactions among natural enemies may result in complex effects of enemy diversity on prey consumption. Therefore, the challenge in understanding natural enemy diversity effects is to predict consumption rates of multiple enemies taking into account effects arising from patterns of prey use together with species interactions. Here, we show how complementary and redundant prey use patterns result in additive and saturating effects, respectively, and how ecological interactions such as phenotypic niche shifts, synergy and intraguild predation enlarge the range of outcomes to include null, synergistic and antagonistic effects. This study provides a simple theoretical framework that can be applied to experimental studies to infer the biological mechanisms underlying natural enemy diversity effects on prey.

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