Spatial pattern and parasitisation of rose shrubs (Rosa spp.) by Diplolepis rosae
Abstract
Aggregation is a biologically significant property of parasites, because distribution of parasites between hosts is usually aggregated: on a few hosts there are many parasites, while on the majority of hosts there are just a few. We studied the effect of changes in spatial pattern and density of rose shrubs on its parasitisation by D. rosae cynipid wasps. The study was made during two years on eight sample sites. Our results show that rose shrubs on high densities show uniform distribution, while on low densities they appear aggregated using discrepancy and patchiness indices. Aggregated pattern of rose shrubs has a negative correlation with aggregation of galls on shrubs. Spatial distribution of rose shrubs has an effect on parasitisation too, with growing aggregation increases the prevalence of D. rosae.
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