Diversity and Host Blood Meal Analysis of Culicoides (Diptera: Ceratopogonidae) from Laos

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.