Ground beetle assemblages and distribution of functional traits in olive orchards and vineyards depend on the agricultural management practice

Biodiversity in the Mediterranean is undergoing a decline resulting in reduced ecosystem service provisions. Here we analysed the functional diversity of ground beetles in Mediterranean vineyards and olive orchards using species traits connected to their ecosystem services. Since previous studies showed that habitat type can affect ground beetle trait composition we hypothesized that the proportion of selected traits (body size, feeding preferences, and wing development) would be influenced by integrated pest management (IPM) and organic management (OM), and this would differ from unmanaged habitats. We analysed published data originating from vineyards and olive orchards in several Mediterranean countries with similar agricultural management practices, and for which ground beetles were sampled in a comparable way. We found that significantly more carnivorous species than herbivorous and omnivorous were present from unmanaged habitats compared to OM sites, while there were no significant differences between OM and IPM sites for ground beetles feeding preferences. The proportion of large brachypterous species was highest at unmanaged sites and lowest at IPM sites. Conversely, functional diversities in feeding preferences and size ranges were significantly lower at unmanaged sites. In Croatian sites only, medium-sized macropterous carnivores were the most abundant beetle fauna, with more predatory individuals found in OM sites. Overall, unmanaged habitats supported a higher proportion of carnivorous ground beetle species, while size and wing development were more variable among the sites.