Ecological zonation and phylogeographic structure of Glossina pallidipes (Diptera: Glossinidae) in eastern and southern Africa

Glossina pallidipes, a major vector of African trypanosomiasis, plays a notable role in disease transmission across eastern and southern Africa due to its broad host range, ecological adaptability, and vectorial capacity. This study combined machine learning using 69 environmental, climatic, edaphic, and developmental variables and genetic analysis to delineate the environmental and phylogenetic structuring of G. pallidipes populations. Kernel density estimation revealed three primary hotspots in the Ethiopian and East African Highlands and the Northern Zimbabwe Lowveld, with a secondary focus along the Maasai Steppe. Most occurrences were associated with tropical savanna climates and sparsely populated natural and semi-natural landscapes. Ensemble modelling using five algorithms identified temperature seasonality, precipitation of the coldest quarter, and diurnal temperature range as the strongest predictors of occurrence, highlighting the dominant influence of thermal variability over precipitation metrics. Among developmental factors, larviposition and mortality rates during the dry quarter were most influential, reflecting the role of humidity in reproductive success. K-means Clustering revealed three ecologically distinct groups following an east–west gradient, shaped by elevation, aridity, and thermal variability. Decision tree analysis identified the Köppen Aridity Index and elevation as key discriminators among clusters. Phylogenetic analysis of mitochondrial COI sequences demonstrated clear geographic structuring, with a divergent Ethiopian lineage and high connectivity between Kenyan and Tanzanian populations. Frequent co-occurrence with the African buffalo and the common warthog further supports ecological continuity across savanna mosaics. These results reveal that G. pallidipes populations are primarily structured by climatic gradients and regional connectivity, informing targeted, region-specific vector control strategies.