Spatial variability of hosts, parasitoids and their interactions across a homogeneous landscape

Species assemblages and their interactions vary through space, generating diversity patterns at different spatial scales. Here, we study the local-scale spatial variation of a cavity-nesting bee and wasp community (hosts), their nest associates (parasitoids), and the resulting antagonistic network over a continuous and homogeneous habitat. To obtain bee/wasp nests we placed trap-nests at 25 sites over a 32 km2 area. We obtained 1541 nests (4954 cells) belonging to 40 host species and containing 27 parasitoid species. The most abundant host species tended to have higher parasitism rate. Community composition dissimilarity was relatively high for both hosts and parasitoids, and the main component of this variability was species turnover, with a very minor contribution of ordered species loss (nestedness). That is, local species richness tended to be similar across the study area and community composition tended to differ between sites. Interestingly, the spatial matching between host and ...