Organic fertilisation enhances generalist predators and suppresses aphid growth in the absence of specialist predators

Biological control by natural enemies is a valuable ecosystem service. The predator community in crop field combination of predators dwelling the and those moving into it from surrounding landscape. former mainly affected management, latter more composition Yet, separate combined effects local landscape management on pest suppression have seldom been investigated. We set-up mesocosms within an existing long-term agricultural experiment to investigate organic manure or inorganic mineral fertilisation, simulated spillover different types: no predators, generalist (wolf spiders) specialist (ladybirds). examined whether aphid density was driven top-down bottom-up processes under fertilisation treatments, how magnitude composition. found positive synergistic between growth. Top-down aphids effective presence Bottom-up plant biomass growth dominated inorganically fertilised plots. Organic gave same yield, but through mechanisms. abundance locally emerging treatment increased yielding levels comparable with plants, being effects. Synthesis applications. enhanced emergence increasing suppression. In contrast, communities were unable suppress populations treatments. Here, inflow outside essential for lowering population Managing landscapes promote mobile emerges as particularly important fields without amendments. advise active promotion both secure conservation biological insect