Effects of landscape heterogeneity on crop colonization by natural predators of pests in protected horticultural cropping systems

Abstract: In Mediterranean regions, colonization of protected horticultural crops by native predatory mirid bugs is frequent, but these processes remain highly heterogeneous among crops. Our study aimed at assessing the effects of crop management practices and local landscape heterogeneity (landscape composition and configuration within 300 m buffers around crops) on populations of Macrolophus and Dicyphus mirids in protected tomato crops in southern France. We found significant effects of landscape heterogeneity on mirid populations, but effects were similar for landscape composition and configuration. Tomato crops were colonized the most by Macrolophus mirids in landscapes with fallow, that seemed to act as source of mirids for crops. In contrast, crop colonization was reduced by nearby orchard, which reflected either sink or dilution effects. Mirid popuations were also reduced in crops with intensive management practices. Maintaining large areas of fallow is important to enhance native beneficial fauna, but adopting integrated plant management practices remains the most promising strategy to enhance mirid populations in protected horticultural crops.