Forest structure and heterogeneity increase diversity and alter the composition of host-parasitoid networks

Antagonistic host-parasitoid interactions can be quantified using bipartite and meta networks, which have the potential to reveal how habitat structural elements relate to this important ecosystem function. Here, we analysed the host-parasitoid interactions of cavity-nesting bees and wasps, as well as their abundance, diversity, and species richness with forest structural elements from 127 forest research plots in southwestern Germany. We found that parasitoid abundance, diversity, and species richness all increase with host abundance, a potential mediator between parasitoids and forest structure. Both parasitoid abundance and diversity increased with stand structural complexity, possibly mediated by the abundance of hosts. Additionally, parasitoid abundance increased with increasing standing deadwood and herb cover. The bipartite networks of host-parasitoid interactions showed higher connectance with increasing standing deadwood, herb cover, and host abundance. Analyses of interactions..., Data were gathered by sampling cavity-nesting bees and wasps using trap nests. The abundance and parasitism events in the trap nests were recorded during nest opening, with individuals reared for species identification., , # Forest structure and heterogeneity increase diversity and alter the composition of host-parasitoid networks

### Builder species matrix

* Plot and corner correspond to the plot and corner where the trap nests containing the individuals of each species were collected.
* Each species column is labeled with the capitalised first letter of the genus followed by the species name (e.g. A_antilope represents *Ancistrocerus antilope*). The complete species list with full genera names can be found in the supplement.
* Columns with full genera names contain individuals that could not be identified as species. The T_clavicerum_group contains specimens that could be identified as only a grouping of similar species. Analyses included only specimens that could be identified at the species level.

### Parasitoid species matrix

* Plot and corner correspond to the plot and corner where the trap nests containing the individuals of each species were collected.
* Each species column is labele...