Influence of species composition of biocorridors on the abundance of aphids in cereal fields

Agriculture intensification in most European countries over the last 50 years resulted in a significant loss of biodiversity in agro-ecosystems. Attempts are now being made to restore originally complex agricultural landscapes by splitting large fields into smaller units using biocorridors, which are linear elements consisting of trees and shrubs. Such non-crop habitats can act as refuges both for insect predators that may potentially act as biocontrol agents and for insect pests. Bird cherry, Prunus padus (L.), is a winter host of a cereal pest and vector of cereal virus, the aphid Rhopalosiphum padi (L.), and is commonly planted in these biocorridors. The question arises, whether and to what extent the presence and distribution of P. padus in biocorridors influences the abundance of R. padi in nearby fields. This was addressed by monitoring spatial and temporal population dynamics of R. padi in two fields each adjacent to the newly established biocorridor but adjacent to parts of the corridor with different species compositions (only one with P. padus). Our results showed that this aphid colonized the field adjacent to that part of the corridor with P. padus but not the other field. In the second field colonization started close to one edge distant from the corridor and with no P. padus in the vicinity. After excluding the variability explained by spatial and temporal factors we also tested for the effect of environmental factors (weather conditions) on the remaining variability. Of the environmental factors tested, humidity accounted for most of the variability.