Management matters: A comparison of ant assemblages in organic and conventional vineyards

Agriculture is one of the dominant types of soil use throughout the world, and understanding patterns of species distributions across agroecosystems is a significant challenge for the future. The intensive use of agrochemicals affects the presence and distribution of several taxa, and organic agricultural methods are believed to be more environmentally sound than conventional ones. In general, organically grown crops host higher species richness for many different taxa, although this evidence is not always unequivocal. The aim of this study was to contribute to understanding whether different management options (organic vs. conventional) affect ant assemblages in vineyards, one of the most important permanent crops in Mediterranean-type environments. To this purpose, we analyzed ant assemblages from organic and conventional vineyards in the Chianti area, Italy. To reduce confounding effects, we chose vineyards with similar soil management (frequency of tillage) and placed within a comparable habitat matrix. The results of this study showed that organic and conventional vineyards hosted a similar species pool, but the structure of their assemblages differed and the effect of insecticides particularly appears to be relevant. Both ant abundance and the number of species per unit area were significantly greater in organic than conventional vineyards. The use of insecticides appeared to be particularly relevant given that vineyards that did not use insecticides also had greater alpha and beta diversity than vineyards where these chemicals were used.