The giant water bug, Lethocerus indicus (Lepeletier and Serville, 1825 Lepeletier, A.L.M. , and Serville, J.G.A. (1825), ‘Belostoma Section’, in Encyclopédie Méthodique. Histoire Naturelle Des Animaux Volumes 10. Paris: Chez Panckoucke, Imprimeur-Libraire, pp. 271–273. [Google Scholar] ), is one of the most important edible insects in Thailand. This study investigated the genetic diversity of L. indicus from natural resources in northeast Thailand by using mitochondrial DNA sequences. Ninety adults of L. indicus were collected from 12 different localities by light trap and hand-net methods. Nucleotide and haplotype diversity of cytochrome c oxidase subunit 1 (CO1) sequences were relatively high. The 43 CO1 haplotypes (Li1–Li43) with 26 unique haplotypes were classified and used to generate a star-like haplotype network. The most common haplotypes were Li6 and Li2 shared between 19 and 15 sequences, respectively from nine different localities. A phylogenetic tree clearly separated L. indicus from the other species and closely clustered with a sibling species, L. patruelis (Stål, 1854 Stål, C. (1854), ‘Nya Hemiptera’, in Öfversigt af Kongliga Vetenskaps-Akademiens Förhandlingar Volume arg. 10. Stockholm: P.A. Norstedt & Söner, pp. 231–255. [Google Scholar] ). However, the comprehensive genetic variation of L. indicus covering broad range of areas needs to be further explored.

Jewel beetles of the genus Sternocera are widely distributed across tropical regions, including Thailand and Lao PDR, where the green-legged S. aequisignata Saunders, 1866, and red-legged S. ruficornis Saunders, 1866, are commonly found. These jewel beetles have significant economic importance, as they are edible, and their iridescent wings are used to create jewelry, leading to high market demand and intensive harvesting. Additionally, their habitats are being rapidly destroyed, resulting in population decline. However, genetic information on these species remains limited. This study aims to investigate the genetic diversity of S. aequisignata and S. ruficornis from various localities in Thailand and Lao PDR using mitochondrial cytochrome c oxidase subunit 1 (CO1) and 16S ribosomal DNA (16S rDNA) sequences. High genetic diversity was observed, with 45 and 62 CO1 haplotypes and 35 and 28 16S rDNA haplotypes identified in S. aequisignata and S. ruficornis populations, respectively. Haplotype network and phylogenetic analyses clearly distinguish S. aequisignata from S. ruficornis. Based on CO1 sequences, S. aequisignata was divided into three distinct haplogroups (GG1–GG3). Haplogroup GG1 was the most widespread, occurring in both Thailand and Lao PDR, while haplogroups GG2 and GG3 were restricted to some localities in northern, western, and northeastern Thailand, as well as Lao PDR. These findings suggest the presence of cryptic diversity within S. aequisignata, with at least three genetically distinct groups. Further comprehensive studies on the biology, ecology, and genetic diversity of these jewel beetles across their distribution range are essential to better understand their evolutionary dynamics.

Spilostethus pandurus is a phytophagous insect widely distributed across Asia, Europe, and Africa, yet its genetic variation remains poorly understood. This study presents the first comprehensive analysis of the genetic diversity and structure of S. pandurus in Thailand using mitochondrial cytochrome c oxidase subunit 1 (CO1) sequences from 202 individuals across 27 localities. A total of 58 haplotypes were identified, with high haplotype and nucleotide diversity observed, suggesting substantial genetic variation. The haplotype network revealed a star-like topology, indicating recent population expansion or ongoing gene flow. Neutrality tests and mismatch distribution analyses showed no strong signal of recent demographic expansion. Phylogenetic analysis confirmed that all Thai specimens clustered within a well-supported S. pandurus clade along with sequences from India, Namibia, and Europe. Analysis of Molecular Variance (AMOVA) revealed significant genetic differentiation among four continental groups, indicating that geographic isolation and restricted gene flow have shaped genetic divergence at a broad biogeographic scale. Further research using highly polymorphic nuclear markers is recommended to better resolve the population structure and evolutionary history of S. pandurus in Thailand and beyond.

Platycorynus peregrinus (Herbst, 1783) is a leaf beetle of agricultural importance, yet its genetic diversity and population structure remain poorly understood. We analyzed mitochondrial cytochrome c oxidase subunit I (COI) sequences from 147 individuals across 19 populations in Thailand. Forty-five haplotypes were identified, showing high haplotype diversity (0.942) and moderate nucleotide diversity (0.00562). Significant genetic differentiation (Φ_ST = 0.0000–0.7857) was strongly associated with geographical distance, and this population structure was further supported by AMOVA (F_CT = 0.21925, p < 0.001). Neutrality tests and mismatch distribution analyses revealed signals of population expansion, alongside evidence of localized differentiation. The substantial genetic variability observed suggests high dispersal ability and possible cryptic lineages. These insights not only advance understanding of the evolutionary dynamics of P. peregrinus but also provide valuable guidance for developing sustainable pest management strategies.

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.

Five edible species of the genus Kaempferia—K. minuta, K. phuphanensis, K. sisaketensis, K. takensis, and K. udonensis—in Thailand were cytologically studied by their root tips. The somatic chromosome numbers of all species were found to be 2n = 22, and the FNs of all species were revealed to be 44. The karyotype of all five rare and endemic species was provided: 10m + 12sm with three satellites for K. minuta, 12m + 10sm with six satellites for K. phuphanensis, 18m + 4sm with four satellites for K. sisaketensis, 6m + 10sm + 6st with three satellites for K. takensis, and 14m + 2sm + 6st with two satellites for K. udonensis. This research identified all new karyological information regarding the chromosome number, FN, karyotype, and ideogram of all the species. They all had a symmetrical karyotype. The chromosome structures and karyotype formula of five edible Kaempferia species from Thailand can be used for species identification.