Hippobosca equina as an emerging threat in northern temperate zones: Species distribution modelling under climate change

Climate change poses significant threats to arthropod vectors of veterinary importance. Hippobosca equina, the forest fly, is an obligate ectoparasite of ungulates with demonstrated capacity for pathogen transmission. We employed maximum entropy modelling to predict current and future global distribution patterns of H. equina under climate change scenarios. Using 1195 occurrence records and five bioclimatic variables, we generated models for present conditions and future projections (2050s and 2070s) under SSP 3-7.0 and SSP 5-8.5 scenarios. Model performance was robust (AUC = 0.954, TSS validation confirmed). Mean temperature of warmest quarter, temperature seasonality and precipitation seasonality contributed most significantly to distribution patterns. Current suitable habitat centres in temperate Europe, with secondary distributions in western Asia and scattered localities globally. Future projections indicate poleward range shifts, with significant habitat expansion into northern Europe, Russia and North America, while southern temperate regions experience habitat contraction. Quantitative predictions indicate that suitable habitat may increase by up to 24.98%-28.81% and decline by up to 11.45%-17.53% relative to current distributions, depending on the emission scenarios, with the most pronounced turnover occurring under SSP5-8.5 by the 2070s. These findings provide critical baseline data for surveillance programs and inform veterinary public health strategies in regions facing imminent colonization risk.