Oecologia

, Volume 157, Issue 3, pp 521–530

Community structure in ichneumonid parasitoids at different spatial scales

  • Sally E. M. Fraser
  • Calvin Dytham
  • Peter J. Mayhew
  • David Mouillot
  • Barbara J. Anderson
Community Ecology - Original Paper

Abstract

The processes underlying parasitoid community structure are little known. Stochastic niche-apportionment models provide one route to underlying assemblage rules in this and other groups. Previous work has applied this approach to parasitoids found on single host species in single populations. However, parasitoid communities are known to extend across multiple hosts and scales. The patterns of relative abundances generated by five niche-apportionment models were compared to those observed in assemblages of two sub-families of the Ichneumonidae, the Diplazontinae and Pimplinae, at landscape and patch scales, Yorkshire, UK. Three of the five models produced patterns that were significantly different to the observed pattern for all taxonomic levels at both spatial scales. The Diplazontinae fit the random fraction (RF) model at the landscape scale in broadleaved woods. This suggests that hierarchical structuring and biotic interactions may play a role in the structuring of Diplazontinae assemblages at this scale. In contrast the Pimplinae fit the RF model only at the patch scale and only at one site. However, the Pimplini tribe (all chiefly parasitoids of Lepidoptera) fit the random assortment (RA) model at both the landscape and the patch scales, whilst the Ephialtini tribe (wide range of hosts) fit no model at either scale. The ecological interpretation of the RA model suggests that the Pimplini tribe is an unsaturated assemblage, where some of the total available resources are unused. Our results show, through the fit of mechanistic niche-apportionment models, that the processes that may structure ichneumonid parasitoid assemblages are not consistent across taxa and spatial scales.

Keywords

Hymenoptera Niche apportionment Rank abundance Relative abundance distributions Tokeshi models 

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Sally E. M. Fraser
    • 1
  • Calvin Dytham
    • 1
  • Peter J. Mayhew
    • 1
  • David Mouillot
    • 2
  • Barbara J. Anderson
    • 1
  1. 1.Department of BiologyUniversity of YorkYorkUK
  2. 2.UMR CNRS-UMII 5119 Ecosystèmes LagunairesUniversité Montpellier II CC 093Montpellier Cedex 5France

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