The functional landscape: the influence of landscape and management on natural pest suppression in Brussels sprout

This study investigates the effect of green veins in the landscape on the natural control of small white butterfly Pieris rapae Linnaeus and diamondback moth Plutella xylostella Linnaeus in Brussels sprout fields. The abundance of the two herbivores was compared at 22 organic farms in various landscape plots throughout The Netherlands, at four spatial scales, i.e. circles of 0.3, 1,2 and 10 km diameter around the fields. In the surrounding landscape the network of line features as hedgerows and trees and the total horticultural area varied strongly. We found that abundance of larvae from both species was negatively correlated with the length of hedgerows in the landscape (scale of 2 km diameter). Numbers of larvae of both species were higher in Brussels sprout fields in agricultural landscapes with a larger total horticultural area. The results suggest that landscapes with dense networks of hedgerows and a limited horticultural area may have potential for pest control.