The spatial dynamics of predatory arthropods and the importance of crop and adjacent margin habitats.
Understanding the distribution patterns and scale of patchiness of beneficial arthropods in fields and field margins, and the spatial and temporal stability of these patterns, can provide valuable information on their ecological requirements and management. The distribution of predatory arthropods (beetles and spiders) was monitored across 66 ha of arable land encompassing six fields and their boundaries using a grid of 973 pitfall trap locations. Sampling was conducted during June and July from 2000-2002. Predatory arthropods increased in number from June to July. They were aggregated into patches, but the location of these differed to some extent between years. Higher numbers of predators were captured in pea compared to cereal fields. Extending the proportion of non-crop area using set-aside in years 2 and 3 increased the numbers of predators up to 100m from these areas by 8% in July.