Landscape conservation and local interactions with non-crop plants aid in structuring bee assemblages in organic tropical agroecosystems

Landscape structure and local floral resources can modulate bee diversity and ecological interactions in agroecosystems. Theory predicts that, at different spatial scales, both factors may interact and influence assemblage patterns and interactions simultaneously, ultimately affecting the provision of ecosystem services. We investigated how habitat heterogeneity at different spatial scales influenced the assemblage of tomato flower-visiting bees in organic cropped areas in the Cerrado biome, Brazil, from 2019 to 2020. We also evaluated the structure and stability of the interaction network among tomatoes, non-crop plants, and bees. We found that landscape heterogeneity can benefit and serve as a source of bee species when natural vegetation remnants are not highly fragmented in the landscape. Non-crop plants increase the permeability of agroecosystems to bees by providing additional and diverse floral resources. The interaction network between non-crop plants and bees was found to be modular and robust, suggesting spatial habitat partitioning among the bee species. The presence of non-crop plants plays a central role in preventing bee species loss in the cropped areas by locally maintaining the stability of the interaction network. Implications for insect conservation Factors operating at multiple spatial scales determine species occurrence in the landscape, but local interactions with non-crop plants dictate habitat permeability to species. Such factors should be considered when designing strategies to make tropical agroecosystems more permeable and functional to bee biodiversity and the pollination services they provide.