Proximity of complementary habitats affects natural pest control

Abstract: Natural enemies of agricultural pests benefit from landscapes that provide
complementary resources in diverse habitats throughout the year. Yet, the influence of
landscape composition and configuration on natural pest control is poorly understood and
empirical studies are often limited in scope. To address this, we developed a spatially explicit
model, simulating the seasonal dynamics of predatory hoverflies and their aphid prey with
various habitat types and configurations. The model incorporated woody habitats, flower strips, and an early and late crop differing in timing and type of resource availability. Woody habitat provides aphid prey and floral resources in spring and autumn, flower strips provide floral resources in summer and the two crops provide aphid prey in different periods in summer.
We demonstrate that pest suppression improves when semi-natural habitats cover a large
area, with woody habitats having a larger effect than flower strips of equal size. Pest suppression further improves when crop field borders consist of flower strips as well as woody habitats, but the proximity of woody habitats is particularly critical for the early crop. Smaller crop fields strongly enhance pest control, especially when adjacent to the other crop.
Overall, the findings highlight that both habitat composition and spatial configuration can
strongly influence natural pest control. Thus, designing agricultural landscapes to ensure year-round supply of essential resources for natural enemies can increase biological control and contribute to more sustainable farming systems.