Global potential distribution and realized niche conservatism during biological invasion of Culicoides imicola from Africa to the Mediterranean basin of Europe

Abstract

Many Culicoides species transmit arboviruses that affect animals and humans. Culicoides imicola, a key vector of bluetongue virus (BTV), has expanded its range from Africa to Europe, spreading disease. Biting midges breed in diverse habitats and contribute significantly to the epidemiology of vector-borne diseases. In the present study, C. imicola occurrences were obtained and spatially filtered, resulting in 703 occurrences divided into the training and validation datasets (a 70–30 % split). Four bioclimatic variable sets were created based on their contributions to environmental niche modeling. Ecological niche models were built using combinations of variables and feature classes, and evaluated based on the Akaike information criterion, the omission rate, and partial receiver operating characteristic curve analysis using the Kuenm package in R version 4.2.3. Niche comparison between the native (Africa) and invaded (Europe) regions was performed using NicheA 3.0 and niche dynamics, including unfilling, expansion, and stability, with ecoregions delineating native and invaded areas determined using the Ecospat package in R version 4.2.3. The results indicated that C. imicola had a wide transcontinental distribution; the model predicted suitable habitats mainly in subtropical and temperate zones. The niche overlap analysis showed that the Jaccard index and Schoener’s D predicted low niche overlap between the native and invaded areas, with limited expansion and 93.6 % niche stability. The niches of C. imicola’s native and invaded areas were more similar than would be expected by chance, but they were not equivalent. In conclusion, there was high niche stability for C. imicola between Africa and Mediterranean Europe, with temperature strongly influencing its distribution.