The potential of agri-environment schemes to enhance biocontrol in arable crops.

Abstract

Many of the existing agri-environment options will support pest natural enemies through the provision of an overwintering environment, a source of alternative food or a refuge from disturbance. The extent to which these improve biocontrol or encourage crop pests remains largely unquantified. A number of fundamental questions remain to be answered before agri-environment schemes can be fully utilised for biocontrol. These include identifying: which types of natural enemy are the most effective and should be encouraged; how these operate across the landscape and what proportion of the landscape should be devoted to the creation of beneficial habitats and how these should be arranged spatially. Methods to quantify the impact of agri-environment options should focus on quantification of pest control rather than measurements of natural enemies per se because their abundance and diversity varies hugely according to habitat quality and surrounding land management. Moreover, because of the complexity and instability of agroecosystems, relationships between natural enemy abundance and pest control are likely to be highly variable and unpredictable. Habitat diversification may add resilience to the system and thereby improve the consistency of biocontrol.