Flower–bee interaction assessment of roadsides to sustain pollinator richness in northern Argentine Pampas

Abstract

Agricultural intensification has simplified rural landscapes, threatening pollinators and the ecosystem services they provide. In the northern Argentine Pampas, roadside verges represent some of the few remaining semi-natural habitats embedded within intensively cultivated matrices. We evaluated whether these linear habitats can function as refuges for bee communities and identified plant assemblages that enhance floral resource continuity and pollinator visitation. Between 2013 and 2015, we recorded plant–bee interactions along eight roadside verges in Santa Fe Province, obtaining 1129 visitation records involving 21 bee species and 33 mellitophilous plant species. Interaction networks were strongly dominated by Apis mellifera (76.8% of visits), while Protandrena sp. 2 and Rhophitulus sp. 1 were the most frequent native bees. Sampling completeness was high for dominant species, although richness-based coverage varied among sites, indicating the presence of low-abundance taxa. We applied a genetic algorithm to identify native plant assemblages that maximize floral continuity and bee visitation, considering scenarios with and without A. mellifera. The optimization identified alternative seven-species plant mixes characterized by complementary flowering periods spanning multiple seasons. Floral abundance of selected plant species was positively associated with bee visitation along road verges. These results highlight roadside verges as important refuge for pollinators and provide a practical framework for managing roadside vegetation to support bee diversity in intensively managed agricultural landscapes in the northern Argentine Pampas.