Author: Morillas Agreda Emmilce
Coauthors: Garcia Molinos Jorge and Garitano-Zavala Álvaro

Pollination is one of the most crucial ecosystem services, playing a decisive role in supporting sustainable development worldwide. However, the global decline of pollinators has significant ecological and economic consequences. Urbanization, which disrupts natural habitats, is a major driver of pollinator biodiversity loss. Despite this, existing knowledge on how urbanization affects pollinators is geographically biased, predominantly focusing on developed regions such as Europe and the USA, while much less is understood about areas that remain underrepresented.
Accordingly, this work presents two independent studies assessing the impact of urbanization on insect pollinators in the cities of La Paz (Bolivia) and Sapporo (Japan). In each study, pollinator communities were analyzed along an urbanization gradient categorized from high to low, based on vegetation characteristics and impervious surface percentage. Pollinator diversity was evaluated through field sampling using entomological nets and colored pan traps, between October and May in Bolivia and from May to September in Japan. Additionally, plant species diversity was recorded to assess its influence on pollinators and their interaction networks.
Pollinator richness, abundance, and composition declined in highly and moderately urbanized areas, leading to more homogeneous and simplified communities. In La Paz, native flower richness was a key determinant of bee diversity. In Sapporo, pollinator diversity was influenced by multiple factors, including distance to the city border, impervious surfaces, and flower abundance and richness. Bees and beetles were the primary pollinators driving differences between urbanization levels. Furthermore, flower-pollinator interactions were more frequent in sites with medium and low urbanization, suggesting more complex and diverse networks in less urbanized areas.
These findings highlight the importance of urban green spaces in sustaining pollinator diversity, composition, and interactions. Urban green areas should support a high diversity of native and wild floral resources to maintain pollinator communities in cities. The loss of such resources contributes to pollinator community simplification, reducing essential ecosystem services. Therefore, strategic urban planning for pollinator conservation is essential for achieving the Sustainable Development Goals (SDGs), particularly those related to sustainable cities.
Keywords: Bees, cities, diversity, richness, composition, interactions, green areas, environmental management, sustainable development.