Climatic and meteorological factors shaping the potential activity season of sand flies in Southeast Europe

Sand flies, the principal vectors of Leishmania spp., are widely endemic in the Balkans and its neighbouring area. Among many factors, meteorological constraints shape sand fly distribution and activity, and are therefore important to assess to understand sand fly occurrence and prevent transmission of pathogens. To determine the daily limits of sand fly activity in Southeast Europe, we used entomological trapping data of eight species from seven countries, as well as temperature, precipitation, global radiation, wind speed, and sea level pressure data of the E-OBS gridded dataset. While 91.3 % of analyzed sites represented humid subtropical-continental ecotypes, heterogenous meteorological activity thresholds were found between species. By ranking the species based on their meteorological limits, Phlebotomus balcanicus and Ph. papatasi showed the widest general meteorological tolerance, whereas the activity of Sergentomyia minuta, Ph. tobbi, and Ph. simici were observed to be most sensitive to meteorological changes. However, principal ordinate analysis suggested that Ph. neglectus and Ph. mascittii had the widest ecological niches related to their activity constraints, and Ph. tobbi and Ph. simici had the narrowest. Phlebotomus mascitti and Se. minuta exhibited the most notable overall dissimilarity of the meteorological requirements of activity. The ensemble tests showed that the feature importance of different meteorological factors varies by sand fly species related to their activity. This study should help to better understand small-scale differences in sand fly occurrence in Southeast Europe to support future surveys and targeted surveillance to assess pathogen transmission in endemic areas.