Predicting the potential distribution of Aedes albopictus in the Black Sea region at the range edge

Aedes albopictus is a globally invasive species and a major vector of multiple arboviruses that cause human disease. The species has been spreading throughout the Black Sea region since 2011, posing an important public health threat. Here, we use a species distribution modeling to predict the potential distribution of Ae. albopictus including updated field collections from the Black Sea region and georeferenced occurrence data from the European Centre for Disease Prevention and Control, Global Biodiversity Information Facility, and Mosquito Alert. Temperature and precipitation values from WorldClim Bioclimatic data and LandScan human population density data served as environmental variables, and models were run using a maximum entropy algorithm in the Maxent program. Human population density contributed the greatest to model performance, followed by minimum temperature of the coldest month. In the Black Sea region, we observed patchy but notable increases in predicted suitability compared to previous global models, including in less densely populated areas. In addition to multiple coastal areas, temperate rainforests of the Caucasus and around the Bosphorus were predicted to be highly suitable for Ae. albopictus. Our field collections confirm Ae. albopictus at high elevations (1779 m), highlighting the need to include habitats at the interface of areas predicted environmentally unsuitable in transboundary surveillance efforts. Model outputs provide new information for institutions monitoring the spread of this invasive vector. Results indicate the need for comprehensive, region-focused surveillance and control strategies to mitigate Ae. albopictus expansion in areas previously considered unsuitable in Georgia, Turkey, Ukraine, and their neighboring countries.