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 three 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 harbored the most diverse predator
populations. Field size and forest proximity increased abundance and
richness of specific natural enemy taxa, i.e., 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.