Species diversity and host plant associations of ambrosia beetles in Southeast Asian forests of Laos and Vietnam revealed by DNA barcoding

Abstract The ambrosia beetles of subfamilies Scolytinae and Platypodinae (Curculionidae) comprise over 6000 described species across 26 tribes and 246 genera. They represent one of the most ecologically and economically significant groups of wood‐boring beetles. Despite their importance, quantitative data on host plant associations in tropical Asia remain limited. Accurate host records are essential for understanding interaction networks, assessing pest risk and mitigating the spread of invasive species through international plant and wood trade. We developed an integrative DNA barcoding framework to elucidate the host plant associations of ambrosia beetles sampled directly from infested trees in tropical forests of Laos and Vietnam. A total of 27 species across 16 genera were identified based on the mitochondrial cytochrome oxidase I (COI) sequences obtained from 130 beetle specimens belonging to the two subfamilies. Then, a total of 30 plant species across 17 families were identified based on the nuclear ribosomal internal transcribed spacer (ITS) and chloroplast maturase K ( matK ) sequences obtained from the host plants from which the beetles were collected. Quantitative network analyses using frequency‐based indices revealed that interactions were structured and non‐random. Species‐level specialization ( d ′) varied widely, with Xylosandrus crassiusculus acting as the most dominant generalist species. This species was associated with 19 host plant species across 12 families, accounting for 63% of host records. Network‐level specialization (H2′ = 0.65) indicated moderate overall partitioning and compartmentalized interactions, reflecting uneven host use and limited redundancy among partners. Several previously undocumented host associations were recorded, expanding the known host ranges of multiple taxa in the mainland of Southeast Asia. Our findings improve baseline data for tropical beetles. This information can be used to support the biosecurity and conservation strategies for useful timber species in the region.