Biological Rape Pest Control in Spatio-Temporally Changing Landscapes

摘要: Community structure and trophic interactions depend on landscape context. We analysed of the pollen beetle (Meligethes aeneus) its parasitoids oilseed rape (Brassica napus) in 15 agricultural landscapes differing structural complexity (∼50–100% arable land) interannual changes crop area (with ∼7% maximum expansion ∼8% contraction from year to year). A patch potted plants was placed centre each for standardized measurement. Parasitism decreased herbivory increased as percentage land surrounding increased. Thus, semi-natural habitats appeared support parasitoid populations contributing reduction beetle. In addition, parasitism following expansion, contraction, indicating dilution concentration effects higher level populations. When habitat dropped below a value ∼20% landscape, or when between years exceeded ∼5% respectively, threshold about 32–36%, which success classical biological control has never been reported. geographic scale analysis using five spatial scales ranging 0.5 3 km diameter, showed best correlations with both interannually changing crops at same scales, i.e., sectors 1–2 thereby suggesting that this ‘functional scale’ indicates their dispersal abilities.