Effects of landscape complexity on parasitoid diversity and biological controlof cereal aphids

Abstract: We studied aphid-parasitoid complex in wheat agroecosystems in two consequentyears in two contrasting landscape types, simple and complex (defined on the basis of percentageof non-arable land within each 1.5km diameter circular landscape sector). Complex landscapessupported higher parasitoid density and species richness, but also higher density of aphids, thuspossibly counterbalancing the positive effects of biological control. Therefore, both aphids andparasitoids benefited from increased landscape complexity. Parasitism rates gave even less clearconclusion: direction of the effect of landscape complexity on the parasitism rate was opposite intwo consequent years.