Spatial scale mismatches between pest and natural enemies challenge conservation biological control in tropical organic agroecosystems

Abstract Conservation biological control (CBC) is a key strategy for sustainable pest management in organic farming; yet, its effectiveness is influenced by landscape structure. This study investigates how landscape structure (composition and configuration) affects the tomato leafminer ( Phthorimaea absoluta ) and its natural enemies in organic tomato crops in Brazil. Fieldwork was conducted on 20 farms from 2023 to 2024. Pest and natural enemy populations were sampled using pheromone traps, beat sheets, and sticky traps, and biological control was quantified via egg parasitism and predation rates. Landscape metrics were assessed within varying buffer distances using high-resolution land cover data and spatial models. We showed that P. absoluta abundance decreased with increasing natural vegetation cover and increased with agricultural patch connectivity, responding at a broad spatial scale (3.1 km). In contrast, natural enemies responded to finer-scale landscape features (0.8 km for parasitoids and 1.6 km for predators), with abundance linked to natural patch size, richness to natural connectivity, and diversity to natural patch shape. Parasitism was enhanced by natural patch connectivity and fractality but reduced by agricultural connectivity and patch size, while predation remained unaffected. These findings demonstrate a spatial mismatch between pest and enemy responses and highlight the importance of landscape configuration beyond habitat amount in enhancing CBC effectiveness. This research underscores the need for spatially explicit landscape planning that promotes enemy-friendly habitats while limiting pest connectivity, offering actionable insights for the design of agroecological strategies in tropical organic systems.