Whole‐genome resequencing reveals population structure, demographic history, and candidate climate‐associated loci in the Asian citrus psyllid Diaphorina citri

BACKGROUND: Understanding how genomic variation is structured across geography and climate is important for predicting pest responses to environmental change. However, such genome-wide information remains limited for the Asian citrus psyllid (ACP, Diaphorina citri Kuwayama), a major global citrus pest and the principal vector of Huanglongbing in many citrus-growing regions. Here, we analysed whole-genome resequencing data from 199 ACP individuals collected across heterogeneous environments in China to investigate population structure, demographic history, gene flow and candidate climate-associated genetic variation. RESULTS: values ranged from 0.0328 to 0.1551, indicating weak-to-moderate differentiation among groups, with the greatest differentiation involving Group I and low differentiation between Groups II and III. Demographic modelling and TreeMix analyses supported recent gene flow within China. Genome scans identified 281 candidate differentiated genes, and LFMM/RDA analyses detected 6289 environment-associated loci corresponding to 635 genes, including 29 genes associated with Bio10 (mean temperature of the warmest quarter). Among these, the Sgs3-like gene was retained as a representative heat-associated candidate. Expression assays and RNAi knockdown supported a gene-level role for Sgs3-like in heat-stress responses. CONCLUSION: Our study provides a genome-wide framework for understanding population structure, demographic history and candidate climate-associated variation in ACP. Sgs3-like represents a biologically supported candidate for future work on heat-stress responses.