The Role of Diptera in Pollination within a Peri-Urban Forest of Popayán, Cauca, Colombia.

Plant–pollinator interactions are essential for maintaining ecosystem functioning, yet the role of Diptera as floral visitors remains poorly documented in Andean peri-urban forests. This study aimed to characterize the floristic composition and evaluate the interaction network between angiosperms and Diptera in a peri-urban forest fragment in Popayán, Cauca, Colombia.

Floristic surveys were conducted using ten 30 × 2 m transects. Floral visitors were recorded through direct observations following a phytocentric approach during six field campaigns. Only insects contacting reproductive structures and displaying pollinator-like behavior were considered. Captured specimens were identified to the lowest possible taxonomic level, and interaction matrices were used to analyze network structure.

A total of 68 plant species belonging to 31 families were recorded, with Orchidaceae, Rubiaceae, and Araceae being the most representative. Herbs and shrubs predominated, suggesting an intermediate successional stage. Fifty-six interactions involving 33 Diptera species and 18 plant species were documented within a 2.96-ha area. Only 26.5% of the recorded plant species interacted with Diptera, indicating selective use of floral resources. The network exhibited low connectance (0.072), intermediate specialization (H2′ = 0.34), and a nested structure, suggesting that specialist species interact preferentially with generalist species. Psychotria carthagenensis and Miconia theaezans concentrated the highest number of interactions, likely due to their abundant, accessible flowers and prolonged resource availability.

Diptera contribute substantially to pollination processes and network connectivity in this peri-urban forest. Their interactions are associated with specific floral traits and vegetation structure, highlighting the ecological importance of shrubs and understory species in maintaining pollination services and ecosystem resilience in fragmented Andean landscapes.