The association of Mediterranean plant species with herbivorous arthropods and its effect on pest abundance in organic vineyards

Abstract

Non-crop plant resources, such as hedgerows and adjacent woodland areas, may impact the distribution of pest species in the crop. Knowledge on the associations between plants and arthropods as well as their impact on pest distribution is thus key to adequately manage agroecosystems. We selected a number of native Mediterranean plant species located around organic vineyards in Southern Portugal and determined their associations with species of Auchenorrhyncha and phytophagous tetranychid and tenuipalpid mites, including the main species of vineyard pests in the area. We also tested if the abundance of vineyard pests is affected by the distance to the edge and the species of plants present. Most non-crop plants and ground cover vegetation harbored very low numbers of leafhopper pests. Rubus ulmifolius and Tamarix africana proved to be a repository of non-pest Auchenorrhyncha species, with the former also serving as winter repository of the pest Jacobiasca lybica. Rosa canina and Fraxinus angustifolia hosted abundant populations of the spider mite Tetranychus urticae. Still, plots next to plant biodiverse margins harbored fewer numbers of T. urticae, when compared with plots next to other vineyards. Furthermore, pest abundance in vineyards increased with growing distance to plant biodiverse margins. Our results high-light the benefits of biodiverse margins in reducing pest abundance and point to the importance of a good selection of plant species when managing and planning these non-crop plant resources.