Climate change-driven range shifts in a cosmopolitan synanthropic insect: global habitat suitability modeling and projections for Clogmia albipunctata.

Climate change is fundamentally reshaping the geographic distributions of species worldwide, with particular implications for synanthropic organisms closely associated with human environments. Clogmia albipunctata (Diptera: Psychodidae), commonly known as the drain fly, is a cosmopolitan insect of increasing concern due to its ability to establish populations across diverse climatic regions and its documented role as a mechanical vector of human pathogens. We employed maximum entropy (MaxEnt) species distribution modeling to project the global habitat suitability of C. albipunctata under present-day conditions and two contrasting future climate scenarios (RCP 2.6 and RCP 8.5) for mid-century (2050) and end-of-century (2070) timeframes. Based on 7,244 spatially independent occurrence records and five optimized bioclimatic variables (BIO1, BIO7, BIO10, BIO11, BIO12), our current habitat suitability model achieved strong predictive performance (AUC = 0.82, TSS = 0.86). Results indicate that dominant limiting variables are annual mean temperature (BIO1) and annual precipitation (BIO12), with BIO7 (annual temperature range) acting as a key constraint in regions of high thermal seasonality, reflecting the species' sensitivity to temperature fluctuation, while cold-season thermal conditions constrain poleward expansion. Projections reveal heterogeneous range dynamics: tropical and subtropical regions show net habitat loss under high-emission scenarios (RCP 8.5), with losses exceeding 8% in the Mediterranean basin and southwestern North America by 2070. Conversely, temperate and boreal regions exhibit substantial habitat gains, particularly across Central Asia and East Asia (8.9% and 9.2% respectively under RCP 8.5 by 2070). Under the mitigation scenario (RCP 2.6), distributional changes remain modest, underscoring the importance of emissions mitigation for constraining expansion of climatically suitable habitat. The potential expansion of C. albipunctata into previously unsuitable regions raises public health concerns, given the species' documented involvement in myiasis cases and its role as a potential vector of pathogenic microorganisms. Our findings provide a quantitative foundation for anticipating geographic shifts in this medically important species and inform targeted surveillance strategies in regions projected to experience habitat suitability increases.