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Keywords:

  • Coexistence;
  • land use;
  • landscape fragmentation;
  • parasitism rate;
  • parasitoid incidence;
  • tritrophic system

Abstract

  1. When resources are spatially fragmented, strength of competition between species is diminished by alternative patterns of resource use and parasitoids of the same host species become potential competitors. The coexistence of competing species in spatially fragmented habitats may be achieved, however, due to niche partitioning and alternative responses to patch characteristics. To evaluate responses to resource patterns facilitating coexistence, we examined the resource use patterns of four parasitoid species (Orthopelma mediator, Pteromalus bedeguaris, Torymus bedeguaris and Glyphomerus stigma) of the gall inducer Diplolepis rosae at both landscape and local scales.
  2. Parasitoid species of rose gall communities behave differently at landscape and local scales. Parasitism rates and parasitoid incidence showed correlations with local characteristics in some cases, with landscape characteristics in others and, in some other cases with both.
  3. Species responses to the examined characteristics depend rather on life history traits of parasitoids than on their frequency within the community. The examined parasitoids responded differently to landscape and local characteristics, while their phenology corresponded with their responses. Species emerging earlier in spring (O. mediator and P. bedeguaris) responded only to local variations, while later emerging species (T. bedeguaris and G. stigma) were sensitive to landscape characteristics as well.
  4. Differences between species-specific and overall responses highlight the importance of species characteristics when considering multiparasitoid communities, and support both fine and coarse partitioning between different species coexisting in the community.