Landscape-mediated interactive effects of conservation and augmentative biological control in organic agroecosystems

Understanding how landscape structure modulates the interplay between conservation and augmentative biological control remains a critical challenge for sustainable pest management. We investigated how landscape composition and configuration shape the abundance of the tomato pest Phthorimaea absoluta, its natural enemies, parasitism rates, and crop productivity in 10 organic tomato farms in the Brazilian Cerrado. By combining pre- and post-release assessments following the augmentative release of the parasitoid Trichogramma pretiosum, we quantified how vegetation cover, patch size, edge complexity, and connectivity across multiple spatial scales influence multitrophic interactions.

Pest abundance declined with increasing natural vegetation both before and after parasitoid release, but responded to landscape connectivity only after the release. In contrast, different landscape attributes shaped natural enemy dynamics and parasitism rates. Larger and more complex natural patches increased natural enemy abundance, whereas connectivity consistently enhanced parasitism rates both before and after the release. Structural equation modeling revealed that both the composition and configuration of natural vegetation significantly affected pest management and reduced fruit damage following the release of T. pretiosum.

We suggest that more heterogeneous landscapes promote coexistence among residents and introduced enemies, mediating additive effects between conservation and augmentative biological control. The results also suggest an edge-mediated resource-complementation mechanism, in which intricate interfaces between crops and native vegetation enhance the spatial integration of both habitats, thereby improving parasitoid retention and performance. These findings underscore the importance of explicitly incorporating landscape context, particularly configuration, into augmentative biological control programs to maximize their effectiveness and long-term sustainability. © 2026 Society of Chemical Industry.