Does landscape composition affect pest abundance and their control by natural enemies? A review

Landscape management could contribute to sustainable pest control. Landscape composition, in particular, could either directly impact a pest abundance by affecting its dispersal, mortality or reproduction, or indirectly by affecting its natural enemies. We performed an analysis of the scientific literature to assess how the proportion of different land covers at the landscape level is related to the abundance of pests or to their control by natural enemies. Of 72 independent case studies, 45 reported an effect of landscape composition. Results confirmed the suspected suppressive effect of landscape scale amounts of semi-natural areas on in-field pests: landscapes with higher proportions of semi-natural areas exhibited lower pest abundance or higher pest control in fields. Contrarily, there was no clear direction in relationships between pests and pest control and landscape when the latter was described as the overall proportion of cultivated area or as that of crops host to particular pests. The analysis of original articles indicates that this lack of direction may be due to the diversity of land use intensity in the studied landscapes and to a too rough categorizing of land covers. This pleads for a better consideration of the functionality of crops and of their management in landscapes. (C) 2011 Elsevier B.V. All rights reserved.