When size matters: a morphological measurement that informs on the potential pest control function by soil arthropod communities

Promoting pest control provided by soil arthropod communities can enhance sustainable agricultural production. Despite years of research aimed at predicting the pest control potential of these communities, few studies have described natural enemy communities composed of multiple taxonomic orders through a functional lens and identified traits involved in predator–prey interactions. Arthropod predator communities consist of individuals from several taxonomic orders exhibiting significant physical and behavioral differences that likely contribute differently to pest control. These inter-order differences justify the adoption of a functional approach, rather than a taxonomic one, to describe predator communities. However, there is no generalized functional trait identified to describe arthropod predator communities and predict the pest control potential by these communities. To address this knowledge gap, we reviewed 194 relationships from the literature, examining various traits and feeding characteristics for different groups of ground-dwelling arthropod predators (spiders, Coleoptera, and Chilopoda). We tried to determine whether a functional trait can be identified to explain the pest control potential across a multi-taxonomic assemblage. Each relationship was described in terms of the trait, the feeding characteristic, and the direction of the relationship in quantitative studies. Across all taxonomic groups, we consistently observed a positive relationship between predator body size and prey body size. This relationship was the most tested and the most shared among orders. Consequently, this study provides a proxy trait (body size) that can be used to predict a potential of predation and therefore inform on the pest control provided by multi-taxonomic assemblages of predators.