Comparative Study of Potential Habitats for Simulium qinghaiense (Diptera: Simuliidae) in the Huangshui River Basin, Qinghai–Tibet Plateau: An Analysis Using Four Ecological Niche Models and Optimized Approaches

Simple Summary Simulium qinghaiense, endemic to the Huangshui River, serves as a critical environmental indicator for assessing the ecological health of both the river and its surrounding landscapes. Notably, the female adults of S. qinghaiense could directly cause severe economic losses for farmers. Despite its ecological importance, there is currently a gap in research regarding the potential areas of this species within the region. This study marks the first comprehensive integration of the MaxEnt model (with parameter optimization), GARP, BIOCLIM, and DOMAIN models. Utilizing actual survey data on the geographical distribution of S. qinghaiense in the Huangshui River Basin, coupled with bioclimatic and altitudinal variables, we conduct a comparative prediction of the potential areas for this species. All four models exhibit excellent predictive accuracy, surpassing random models, with MaxEnt showcasing superior performance. The primary concentration of suitable areas is observed in the central and southern regions of the Huangshui River Basin. The MaxEnt model is then employed to simulate predictions of distribution and changes across different periods, revealing that the Qilian Mountains may provide a potentially favorable refuge for this species during the ice age. In conclusion, the findings of this study offer a scientific foundation for ecosystem conservation in the Huangshui River Basin, as well as monitoring and early warning for threshold densities of S. qinghaiense. Abstract The Huangshui River, a vital tributary in the upper reaches of the Yellow River within the eastern Qinghai–Tibet Plateau, is home to the endemic black fly species S. qinghaiense. In this study, we conducted a systematic survey of the distribution of the species in the Huangshui River basin, revealing its predominant presence along the river’s main stem. Based on four ecological niche models—MaxEnt with parameter optimization; GARP; BIOCLIM; and DOMAIN—we conduct a comparative analysis; evaluating the accuracy of AUC and Kappa values. Our findings indicate that optimizing parameters significantly improves the MaxEnt model’s predictive accuracy by reducing complexity and overfitting. Furthermore, all four models exhibit higher accuracy compared to a random model, with MaxEnt demonstrating the highest AUC and Kappa values (0.9756 and 0.8118, respectively), showcasing significant superiority over the other models (p < 0.05). Evaluation of predictions from the four models elucidates that potential areas of S. qinghaiense in the Huangshui River basin are primarily concentrated in the central and southern areas, with precipitation exerting a predominant influence. Building upon these results, we utilized the MaxEnt model to forecast changes in suitable areas and distribution centers during the Last Interglacial (LIG), Mid-Holocene (MH), and future periods under three climate scenarios. The results indicate significantly smaller suitable areas during LIG and MH compared to the present, with the center of distribution shifting southeastward from the Qilian Mountains to the central part of the basin. In the future, suitable areas under different climate scenarios are expected to contract, with the center of distribution shifting southeastward. These findings provide important theoretical references for monitoring, early warning, and control measures for S. qinghaiense in the region, contributing to ecological health assessment.