Landscape composition shapes biological control by promoting off-season predator diversity

Landscape heterogeneity can enhance biodiversity, but its impacts are rarely disaggregated over time. Thus, off-season effects on ecosystem service providers, service delivery and underlying (ecological) determinants often remain occluded. We assessed how landscape structure affects predator biodiversity in subtropical rice systems during winter. Furthermore, we investigated the impact of resident predator populations on the adult abundance of the overwintering generation rice stem borer Chilo suppressalis. To study these dynamics, 32,396 insect predators belonging to 52 species (19 families) were systematically surveyed in 19 fallow rice fields over a span of 3 years. Landscape composition and configuration jointly defined overwintering predator diversity, with the former exhibiting the strongest impacts. Rice fields with winter crop cover embedded in complex landscapes harboured the most diverse predator populations. Field size and forest proximity increased abundance and richness of specific natural enemy taxa, that is carabid beetles and hunting spiders. This, in turn, shaped biological control: across sites and years, overwintering pest abundance was negatively correlated with predator richness. Synthesis and applications. Our work demonstrates how off-season crop management and landscape structure jointly support overwintering predator populations and sustain their biological control potential. Specifically, by enhancing winter ground cover and preserving small fields, local rice growers can enjoy cost-free pest biological control and avoid crop protection expenditures in the next cropping cycle.