Urbanization and Apis mellifera roles in plant-animal interaction networks in an urban forest

Pollinating insects are vital to ecosystems, supporting biodiversity, function, and resilience through the services they provide. Urban landscapes affect pollinator abundance and diversity, with both positive and negative outcomes. Understanding interspecific interactions in cities clarifies community organization and function. This study explores the relationship between urbanization and plant-insect visitation networks from two insect orders (Hymenoptera: Apoidea; Diptera: Syrphidae, Bombyliidae) in Chapultepec Forest, Mexico City. Sampling over a year (dry: Nov 2020–Mar 2021; rainy: May–Oct 2021) covered 146 points across the forest and surrounding urban areas. Each point was categorized as low, medium, or high urbanization, based on environmental and urban variables. Connectivity, specialization, nesting, and asymmetry were compared across urbanization levels. A total of 5,430 interactions were recorded, involving 125 plant (60 native, 55 exotic, 10 not defined) and 43 insect (19 native, 6 exotic, 18 not defined) species: 21 Diptera and 22 Hymenoptera. In high-urbanized areas, 28 insect species visited 79 plants; in medium, 20 insects visited 32 plants; in low, 39 insects visited 81 plants. Connectance, nesting, and specialization were similar in high and low levels and higher than in medium. The medium level showed fewer species and generalist dominance (e.g., Apis mellifera ), likely due to local green area management. High nesting values in both low and high levels suggest coexistence of generalists and specialists, increasing network robustness. Apis mellifera was the most influential and central species in all networks, but its importance was lower at low levels of urbanization. These results support strategies for managing urban biodiversity through restoration, conservation, and education programs to preserve pollinators and plant diversity.