Coexistence of natural enemies in a multitrophic host–parasitoid system

Authors

  • Michael B. Bonsall,

    Corresponding author
    1. Department of Biological Sciences and NERC Centre for Population Biology, Imperial College London, Silwood Park Campus, Ascot, U.K.
      *Dr Mike Bonsall, Department of Biological Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, U.K. E-mail: m.bonsall@imperial.ac.uk
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  • Michael P. Hassell,

    1. Department of Biological Sciences and NERC Centre for Population Biology, Imperial College London, Silwood Park Campus, Ascot, U.K.
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  • Patricia M. Reader,

    1. Department of Biological Sciences and NERC Centre for Population Biology, Imperial College London, Silwood Park Campus, Ascot, U.K.
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  • T. Hefin Jones

    1. Department of Biological Sciences and NERC Centre for Population Biology, Imperial College London, Silwood Park Campus, Ascot, U.K.
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    • 1

      Present address: Cardiff School of Biosciences, Cardiff University, PO Box 915, Cardiff CF10 3TL, UK


*Dr Mike Bonsall, Department of Biological Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, U.K. E-mail: m.bonsall@imperial.ac.uk

Abstract

Abstract.  1. This study explored the temporal and spatial aspects of coexistence over many generations in a multispecies host–parasitoid assemblage.

2. The long-term interaction between the cabbage root fly, Delia radicum (Diptera: Anthomyiidae), and two of its natural enemies, Trybliographa rapae (Hymenoptera: Fitigidae) and Aleochara bilineata (Coleoptera: Staphylinidae), in a cultivated field at Silwood Park over 19 years was explored.

3. Although time series showed that the populations were regulated, the impact of the natural enemies was highly variable. Within-year determinants showed that the spatial response of the specialist parasitoid, T. rapae, was predominantly independent of host density while A. bilineata acted simply as a randomly foraging generalist parasitoid.

4. These findings are compared and contrasted with an earlier investigation of the same system when only the first 9 years of the time series were available. This study demonstrated the potential of long-term field studies for exploring hypotheses on population regulation, persistence, and coexistence.

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