This study investigates the prevalence of parasitic helminths in free-ranging domestic cats and dogs near the Chi River and natural reservoirs in Maha Sarakham Province, Thailand. Fecal samples from 39 cats and 148 dogs were analyzed using a modified formalin-ether concentration technique (FECT). The overall prevalence of helminth infections was 64.1% in cats and 51.4% in dogs. Common parasites were detected including soil-transmitted species like Ancylostoma sp. (hookworm), Toxocara spp., and Strongyloides sp., as well as foodborne helminths such as Taenia sp., Hymenolepis sp., Spirometra sp., and Opisthorchis sp. Multiple parasitic infections were commonly found in dogs (57.9%) and cats (46.2%). Our findings suggest that domestic cats and dogs act as important reservoirs for zoonotic helminths in the region. Notably, Opisthorchis viverrini-like eggs were found exclusively in cats, with a prevalence of 23.1%. The intron 5 of domain 1 of the taurocyamine kinase gene (TkD1Int5) was used for genotyping O. viverrini-like eggs. All O. viverrini-like egg samples with TkD1Int5 haplotypes (Ov116–Ov123) were uniquely found in cats. Genetic analysis revealed that TkD1Int5 haplotypes were similar to those previously reported for Opisthorchis viverrini in various species of cyprinid fish across opisthorchiasis-endemic regions in Thailand and Lao PDR. Three TkD1Int5 haplogroups (I–III) were classified, with O. viverrini-like eggs from cats distributed across all haplogroups. Notably, one haplotype (Ov118) was genetically distinct from the others and did not cluster into any haplogroup. These findings highlight the crucial role of cats as reservoir hosts and their potential contribution to the transmission of the zoonotic liver fluke O. viverrini, posing a notable public health concern.

Adult black flies were collected from diverse habitats in five provinces of Laos. In total, 4659 adults (4570 females and 89 males) were collected. Morphological identification, supplemented with the mitochondrial cytochrome c oxidase I gene, revealed 12 species. The most abundant taxa were Simulium khelangense/S. chumpornense and S. asakoae/S. myanmarense with 58% (2628 of 4476) and 38% (1720 of 4476) of the total specimens, respectively. Simulium asakoae/S. myanmarense was the most geographically widespread taxon (65% of sites) from 174 to 1219 m above sea level. The remaining species were far less abundant (<2%) and found in only one or a few locations. Molecular identifications of vertebrate blood meals indicated that most hosts (57 of 66) were chickens. Five taxa, S. asakoae, S. khelangense, S. myanmarense, S. aureohirtum, and S. striatum group, fed on chickens, representing the first hosts records for the latter three taxa. Simulium daoense fed on water buffalo, marking the first record of this species in Laos and the first report of its blood hosts. The abundance and frequent use of domestic chickens as hosts suggests that S. khelangense and S. asakoae could be significant pests and might serve as vectors of avian blood parasites in Laos.

We conducted a comparative chromosomal analysis of 10 nominal species and 3 unidentified species in the Simulium striatum group from six countries. A total of 66 chromosomal rearrangements were found, of which 78.8% were inversions. The group is defined by 11 fixed inversions, of which 6 are unique, supporting the monophyletic status previously indicated by morphological and molecular characters. Only 1 of the 13 taxa had a unique fixed chromosomal rearrangement. Although the group demonstrates significant macrogenomic reorganization, subsequent speciation occurred largely without chromosomal rearrangement. The results conflict with the pattern seen in all other species groups of Simuliidae, in which one or more diagnostic rearrangements are typically expressed among species in the same group. The chromosomes provide limited evidence that four entities are valid species but no evidence for the nine others. The weight of evidence from combined chromosomal, molecular, and morphological data, in addition to the practical considerations made for insular species, supports the species status of seven of these nominal species; the remaining taxa require further study. The S. striatum group, accordingly, is either over-divided into nominal species or deficient in chromosomal discriminators. If most or all nominal species and unnamed species are valid, all but one are homosequential, an unprecedented condition in Simuliidae. This group illustrates the need for the integration of multiple character sets for discovering and delimiting species.

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.

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.

Many biting midge species of the genus Culicoides Latreille are significant pests and vectors that transmit diverse parasites to humans and other animals. However, knowledge of these hematophagous insects in Laos remains limited, with the most recent information reported more than four decades ago. In this study, we investigated Culicoides species diversity, DNA barcoding and host blood sources using specimens collected across seven provinces in northern, central, and southern Laos. A total of 4592 specimens were collected, comprising 3095 females and 1497 males. Morphological identification, complemented by DNA barcode analysis, revealed 26 species (24 named and 2 unnamed), including five (three named and two unnamed) new country records. Culicoides peregrinus was the most abundant species, representing 25.7% (1179 individuals), followed by C. oxystoma at 23.8% (1093 individuals), and C. arakawae/C. mahasarakhamense, which together comprised 18.5% (849 individuals) of the total specimens. DNA barcode analysis demonstrated that this genetic marker is effective for species identification of Culicoides in Laos. Of the 115 COI sequences, 103 (89.6%) were successfully matched with conspecifics in the BOLD database. Cryptic genetic diversity was detected in three species, C. clavipalpis, C. palpifer, and C. huffi, with two, two, and three divergent lineages, respectively. Host blood meal analysis revealed that chickens and domestic water buffalo were the most common blood sources for the investigated Culicoides species. These findings provide important baseline information for future studies on the pest and vectorial roles of Culicoides in Laos.