Genetic Variation and Demographic History of Green Weevil Hypomeces pulviger (Herbst, 1795) (Coleoptera: Curculionidae) in Thailand Examined by Mitochondrial DNA Sequences.

The population genetic diversity and demographic history of Hypomeces pulviger in Thailand were examined based on mitochondrial cytochrome c oxidase subunit 1 (CO1) and 16S ribosomal DNA (16S rDNA) sequence data. A total of 171 and 104 individuals from multiple populations were analyzed using CO1 and 16S rDNA sequences, respectively. The CO1 sequence dataset revealed high haplotype diversity (Hd = 0.999) and moderate nucleotide diversity (Nd = 0.0323), whereas the 16S rDNA showed lower diversity (Hd = 0.750, Nd = 0.0026). Population structure analyses showed low to moderate differentiation in CO1 sequences with a significant isolation-by-distance pattern, suggesting distance-limited gene flow, while 16S rDNA sequences showed weaker structure. Neutrality tests and mismatch distribution analyses supported a recent population expansion, as indicated by significantly negative Fu's Fs and a unimodal distribution. Haplotype network and phylogenetic analyses further demonstrated greater resolution in the CO1 gene compared to the 16S rRNA gene. Collectively, H. pulviger populations in Thailand are genetically diverse, connected, and expanding, likely facilitated by both natural dispersal and agricultural activities. These findings provide important insights for understanding pest dynamics and developing effective management strategies.