Improving natural pest suppression in arable farming: field margins and the importance of ground dwelling predators

Abstract

Overwintering of soil dwelling arthropods and especially carabid beetles was much higher in unmown perennial field margins than in mown grass strips or barren crop fields. Over 200 generalist predators per m2 were trapped in field margin enclosures after hibernation. Predator exclusion experiments showed that high-density aphid colonies in May were reduced by 49% compared to predator-free conditions, both in field margins and in summer wheat crops. Over a 4 years period, aphid infestation levels in summer wheat and potatoes were 15%-65% lower in a farming system with a network of perennial field margins, compared to a system without field margins. However, Diamond back moth and slug damage in Brussels sprouts were higher in the system with field margins compared to the control system without margins