Does the spatial density of field margins affect aerially dispersing aphid predators, if so, at what scale?
A landscape scale study was carried out investigating the effect of field margin density on aerial predators and their aphid prey. Field margins may aid biocontrol of aphid populations by acting as a source of aphid enemies, or they may act as a sink, drawing aphid enemies away from the crop to reside in a more favourable habitat. Results from 12 winter wheat fields with varying densities of surrounding field margins, showed the total number of predators and Cantharidae to exhibit a negative correlation with field margin density at local scales, but predatory Staphylinidae, especially Tachyporus spp. to show a positive correlation with field margin density at larger scales. Implications for pest control are discussed.