Tage der Biodiversität 2027

In Austria, standardized data on hoverflies in agricultural landscapes are currently lacking, although they provide key ecosystem services, including pollination, and are facing populations declines globally. To address this knowledge gap, we systematically surveyed 50 sites in agricultural landscapes, each comprising ten 160 m² cross-transects. Sampling was conducted in 2024 at 40 sites and 2025 at 10 sites, with two or three surveys per site between April and August. In addition to the standardized transects, we investigated microhabitats within each site that displayed high flower or structural richness, where higher hoverfly diversity was expected. Furthermore, at five protected sites, we specifically searched for Brachyopa species and the potentially extinct species Hammerschmidtia ferruginea.

Overall, we recorded nearly 50 % of the hoverfly species known to occur in Austria. Within agricultural landscape, hoverfly diversity was highest in the Alpine region, whereas lower hoverfly diversity was observed in the cropland-dominated eastern Austria. Species diversity varied among habitat types and plant families: particularly high diversity was associated with montane and subalpine pastures and highest number of hoverflies visited plants of the family Asteraceae. Neocnemodon brevidens is new for Austria and 48 species are recorded for the first time in some federal states. At protected sites, we observed 60 % of the Brachyopa species known from Austria, whereas Hammerschmidtia ferruginea could not be detected.

Our project identifies habitat types and plants that are essential for hoverflies and provides an evidence-based foundation for the effective conservation of hoverflies. The results also establish a valuable baseline for future standardized monitoring of hoverfly populations in Austria.