Structure and diversity of hoverflies (Diptera: Syrphidae) in northwestern Colombian Paramos: towards the identification of bioindicator species in the Tropical Andes

Despite their importance as water reservoirs and endemism hotspots, Paramos or tropical alpine ecosystems are threatened by global warming and anthropic activities. An important but often neglected component of paramo biodiversity are hoverflies (Diptera: Syrphidae), which play key roles in the provision of ecosystem services at high elevations where bee abundance decreases. We characterized the spatial distribution of Syrphidae diversity at two Paramo complexes to identify potential bioindicator species for montane habitats. We hypothesized that bioindicator species must be easily detected and exhibit affinity for a particular habitat when replacement between and/or within habitats tend to be strong. Twelve bimonthly samples of ten days were done at Santa-Ines-Belmira and Sonson Paramo complexes in Colombia, comprising 18 sampling stations distributed among three habitat types: paramo, forest, and grassland. Flies were collected using ground and canopy Malaise traps, colored pan-traps, and sweeping. We estimated alpha and beta diversity components within and between habitats. We identified potential bioindicator species based on exclusivity and fidelity criteria. We collected 2783 specimens belonging to 41 genera and 148 species. Paramo had the highest richness and number of collected specimens (110 species, 84% completeness percentage, n = 1878), followed by forest (88 species, 65%, n = 357), and grassland (59 species, 80%, n = 571). Species replacement was the dominant component of incidence-based beta diversity. The similar contribution of nestedness and turnover between paramo and grassland reinforces the hypothesis that grassland communities may represent disturbed paramo. We propose eleven genera and fourteen species as bioindicators of paramo, one genus for forest, and one genus and two species for grassland, potentially useful to evaluate and implement conservation programs in Andean ecosystems. Implications for insect conservation: Bioindicator species facilitate monitoring the state of ecosystems, a necessary procedure to forecast and mitigate changes due to climate change and anthropogenic advances. Paramos harbor great species richness in relatively small areas and are under constant threat due to agricultural and mining practices. The conservation of these habitats will guarantee not only the continuity and persistence of ecological services provided by hoverflies but also the protection of a unique component of the world’s biodiversity. Bioindicator species facilitate monitoring the state of ecosystems, a necessary procedure to forecast and mitigate changes due to climate change and anthropogenic advances. Paramos harbor great species richness in relatively small areas and are under constant threat due to agricultural and mining practices. The conservation of these habitats will guarantee not only the continuity and persistence of ecological services provided by hoverflies but also the protection of a unique component of the world’s biodiversity.