The response of predatory arthropods to crop and land-use intensity in an arable ecosystem

Abstract: The aim of this study was to assess the response of predatory arthropods as potentially valuable biocontrol agents to intensity in cropping practice and land-use at field, field boundary, and landscape scales. A multi-model inference approach was used to analyse the variation in pitfall trap counts from forty arable field sites in Scotland. Several intensity variables were found to be important determinants of arthropod abundance. Although the importance of the determinants varied between the predator groups (carabids, spiders, and staphylinids), some general patterns were observed. Local, field scale, conditions were of little importance in determining the abundance of predatory arthropods and there was no indication that the taxa considered were adversely affected by cropping intensity. At the landscape scale, predator abundance was positively associated with the proportion of semi-natural habitats (broadleaf woodland and heath) and specific crops, though the influence of semi-natural habitats was typically an order of magnitude greater than that of the crops. The results indicate that habitat complementarity at the landscape scale is more important than landscape complexity in conserving groups of predatory arthropods and support the need to consider both semi-natural and crop habitats in detail to understand the influence of landscape structure on predatory arthropods.