Influence of agricultural management on canopy-dwelling predatory and herbivorous arthropod communities in Swedish apple orchards

Abstract: Local agricultural management, and in particular pesticide usage, is a major driver of many arthropod communities in agroecosystems. For example, it is known to cause a significant impact on pest’s natural enemies abundance and diversity. The aim of our study was to establish the effect of agricultural management on the community of predatory and phytophagous canopy-dwelling arthropods in Swedish apple orchards. Arthropods were sampled from the tree canopy in organic and conventional orchards using a field insect aspirator. We compared the composition at family level of the two functional groups considered (predators and herbivores) using multivariate analysis. Significant differences were obtained for the predatory community between organic and conventional orchards. Principal component analysis showed a clear clustering of conventional farms mainly associated to lower abundances of predatory mirids, anthocorids, ladybirds, dustywings and spiders. Furthermore, there was a higher variation in the predatory arthropod community in organic compared to conventional orchards. No differences were observed for the herbivore community collected in suction samples between management schemes suggesting a different response pattern to orchard management compared to the predatory community during the 2013 growing season.