From conservation to crop pollination: an ecological synthesis of floral planting effects on bee activity within crops

In the coming decades, food demand will likely increase with human population growth, leading to more intensive agricultural practices that threaten bees and their pollination services. This threat is worrisome because many crops depend on bees to produce fruits and seeds, making bee conservation crucial for food security. A sustainable strategy to conserve bees involves establishing floral plantings alongside crops. However, their effects on crop pollination remain contradictory: while some studies show positive outcomes, others report negative or inconsistent results. These contrasting patterns align with two mutually exclusive hypotheses: exporter and concentrator . The former suggests that floral plantings promote pollinator spillover to crops, whereas the latter proposes that they concentrate pollinators for themselves. To explore how to maximize the exporter effect, we synthesized existing knowledge using a research weaving approach that combines bibliometric and systematic mapping to identify the factors and mechanisms that influence floral planting effects. Our synthesis shows that, despite a substantial body of literature on floral plantings, data for specifically assessing bee activity within crops remain limited, and contradictory findings still challenge optimization efforts. Even so, crop type, floral planting composition, bee group, and environmental context emerge as the main interlinked factors driving floral planting effects. Moreover, our synthesis suggests that the concentrator and exporter hypotheses represent sequential stages of the same ecological phenomenon, which we explain as a new integrative hypothesis . Finally, future studies should test how those key factors interact to evaluate this hypothesis and determine pollination outcomes across crops and regions, advancing ecological intensification.