Effects of agroforestry on Phytoseiidae communities (Acari: Mesostigmata) in vineyards. A synthesis of a 10-year period of observations

Several species of the predatory mite family Phytoseiidae are of major economic importance for biological pest control in crops, including grapevines. Plant diversification in agrosystems is reported to enhance useful biodiversity and provide ecosystem services. Thus, agroforestry, which consists in co-planting trees and crops, is assumed to be a possible way to ensure regulation of pest outbreaks by phytoseiid mites. This paper investigates the effect of trees (Pinus pinea and Sorbus domestica) within vineyards on Phytoseiidae communities. Five experimental plots were considered, two where vines were co-planted with P. pinea and S. domestica, and three monoculture plots: vines, P. pinea and S. domestica. Sampling was carried out on vines and trees in 2003, 2004, 2005, 2010 and 2012. A higher Phytoseiidae diversity was observed in agroforestry plots than in monoculture plots. Kampimodromus aberrans (replacing T. [ T. ] exhilaratus) seemed to colonize these plots 15 years after its plantation, especially when vines were co-planted with P. pinea. Factors affecting these faunistical changes are discussed. Effects on Phytoseiidae densities differed depending on grape cultivartree species associations. Factors affecting these interactions are discussed; plant diversity does not simply lead to a higher density and diversity of natural enemies.