The taxon‐ and functional trait‐dependent effects of field margin and landscape composition on predatory arthropods in wheat fields of the North China Plain

Abstract

Abstract Semi‐natural habitats are regularly shown to affect the diversity of predatory invertebrates at both local and landscape scales. In this study, we investigated the effects of three different vegetated field margins and the surrounding landscape composition on two common natural enemy taxa, carabids and spiders, in wheat fields of the North China Plain. Carabids and spiders were sampled using pitfall traps located at 36 wheat fields near three different field margin types – grassy strip, poplar woodland and unvegetated pathway. In‐field diversity of carabids and spiders was not significantly differentiated by field margin type while species richness of total carabids and abundance of small spiders increased with increasing field margin width, and the abundance of adult spiders, ground hunting spiders, small and medium‐sized spiders decreased with increasing distance to the field margin. At the landscape scale, the abundance of all and large carabids was positively correlated with % woodland, while abundances of all and small carabids were negatively correlated with % grassy area. The abundance of spiders was positively related to % grassy area, while the links between % woodland and adult spider abundance in the fields varied between field margin types. Our results indicated that natural enemies showed diverging, taxon‐ and functional group‐specific links to semi‐natural habitats at both local and landscape scales. Both the creation of mixtures between woodlands and grasslands across agricultural landscapes and an increase in field margin width are identified as efficient measures to promote carabid and spider diversity.