Predicting Potential Range Shifts and Molecular Approaches in Four <i>Diolcogaster</i> Ashmead Species (Hymenoptera: Braconidae, Microgastrinae)

<i>Diolcogaster</i> Ashmead is a genus of Microgastrinae (Hymenoptera: Braconidae) wasps with patchy distribution ranges. This study assessed and predicted the geographical distribution of four <i>Diolcogaster</i> species worldwide using field data and species distribution models (SDMs). The models projected the contemporary and future distributional ranges for the twenty-first century. Nine informative environmental variables were employed to model the ecological niche with the MaxEnt model. Furthermore, a maximum likelihood phylogenetic estimation tree was reconstructed using IQ-TREE, with the underlying data being <i>COI</i>-based. Finally, PopART was used to perform a haplotype network analysis to assess the haplotype diversity and evolutionary distances of the four <i>Diolcogaster</i> species. The MaxEnt models showed excellent predictive performance (AUC > 0.9, TSS > 0.8) for all species. <i>Diolcogaster claritibia</i> occupied the widest and most suitable niches globally, followed by <i>D. mayae</i>, <i>D. alvearia</i>, and <i>D. spreta</i>. Molecular analyses supported the predicted models, indicating that <i>D. claritibia</i>'s adaptation to various habitats. Two environmental variables significantly influenced the distribution patterns of the four species. <i>Diolcogaster claritibia</i> and <i>D. mayae</i> are ecologically versatile, adapting to diverse habitats, elevations, and environmental conditions. Thus, their distribution ranges may extend beyond the previously documented limits. The four <i>Diolcogaster</i> species are currently predominantly found in temperate regions, preferring cooler climates. The model predicts that these species will expand into subtropical regions. This study offers a foundational theoretical framework for the practical rearing and strategic use of the wasps, as all Microgastrinae members are important biocontrol agents of caterpillar larvae.