decreased functional diversity and biological pest control in conventional compared to organic crop fields功能和生物多样性减少害虫控制相比,在传统有机农田.pdfVIP

Decreased Functional Diversity and Biological Pest Control in Conventional Compared to Organic Crop Fields 1,2 2 1,2 Jochen Krauss *, Iris Gallenberger , Ingolf Steffan-Dewenter ¨ ¨ 1 Department of Animal Ecology and Tropical Biology, University of Wurzburg, Biocentre, Wurzburg, Germany, 2 Population Ecology Group, Department of Animal Ecology I, University of Bayreuth, Bayreuth, Germany Abstract Organic farming is one of the most successful agri-environmental schemes, as humans benefit from high quality food, farmers from higher prices for their products and it often successfully protects biodiversity. However there is little knowledge if organic farming also increases ecosystem services like pest control. We assessed 30 triticale fields (15 organic vs. 15 conventional) and recorded vascular plants, pollinators, aphids and their predators. Further, five conventional fields which were treated with insecticides were compared with 10 non-treated conventional fields. Organic fields had five times higher plant species richness and about twenty times higher pollinator species richness compared to conventional fields. Abundance of pollinators was even more than one-hundred times higher on organic fields. In contrast, the abundance of cereal aphids was five times lower in organic fields, while predator abundances were three times higher and predator-prey ratios twenty times higher in organic fields, indicating a significantly higher potential for biological pest control in organic fields. Insecticide treatment in conventional fields had only a short-term effect on aphid densities while later in the season aphid abundances were