Alves-dos-Santos, I. | bioRxiv Science

bioRxiv2026

From concentration to export: resource contrasts and bee traits shape pollinator spillover to crops

Floral plantings can either concentrate bees or export them to adjacent crops, yet the ecological conditions influencing these outcomes remain unclear. Here, we develop a mathematical model as proof of concept for our previous integrative hypothesis: concentrator and exporter outcomes can arise as alternative, context-dependent outcomes of the same underlying resource-selection process. Using bees as a model and focusing specifically on spillover from floral plantings to crops, we identified resource-specific thresholds separating concentration- and export-favoring conditions. Our model translates differences in relative patch attractiveness into context-dependent concentration and export outcomes and generates resource-specific, testable predictions about the conditions favoring pollinator movement into crops. In our simulations, the concentrator-exporter transition occurred at a lower flowering-intensity contrast than at pollen or nectar contrasts, which suggests that flowering intensity may provide an initial cue for bee movement, whereas nectar and pollen rewards refine or sustain bee responses once crops are perceived as attractive. Spillover thresholds differed among resource contrasts, whereas response steepness varied across bee-trait and community scenarios. Under the model's trait-sensitivity formulation, predicted spillover probability responded more strongly to flowering contrast for specialists than for generalists; colony size amplified this response, whereas bee richness dampened it. Together, these patterns show how flowering and resource contrasts interact with bee traits and community context to shape predicted spillover. Our results confirm that the concentrator and exporter hypotheses can be understood as context-dependent outcomes of the same ecological process rather than as mutually exclusive alternatives. Experimental tests of the predicted thresholds conducted in the field could reveal when and where floral plantings are most likely to promote bee spillover to crops, potentially supporting crop pollination.

ecology↗

bioRxiv2025

An ecological synthesis about the effects of floral plantings on crop pollination by bees

One of the UNs 17 Sustainable Development Goals is a world free from hunger, with sustainable food production and resilient agricultural practices (SDG 2). However, as we approach the 2030 deadline, global food security, a multidimensional challenge, remains unsolved. With a growing human population, food demand will likely increase, leading to more intensive agricultural practices that put bees and their pollination services at risk. Conserving bees is, thus, crucial to ensuring our food security. A promising solution is cultivating floral plantings alongside crops, which can enhance ecosystem services such as pollination. However, floral plantings may also compete with crops for bees. To optimize their benefits, we need to understand when floral plantings facilitate bee spillover to crops, supporting both bee conservation and agricultural productivity. To address this, we synthesized existing knowledge using a research weaving approach, which combines bibliometric and systematic mapping. Our synthesis suggests that the effects of floral plantings result from a complex interplay of factors, including crop type, bee species, floral planting composition, and environmental conditions. To clarify this interplay, we propose an integrative hypothesis to guide future studies. Finally, our results highlight the need for stronger collaboration among researchers to better understand the role of floral plantings in ecological intensification.

ecology↗