Mosquito arboviral vectors at zoonotic interfaces in border provinces in Thailand

Thailand is a biodiversity hotspot with high risk for spillover of zoonotic mosquito-borne viruses. Mosquito vectors of endemic Flaviviruses, Japanese encephalitis virus (JEV) and dengue virus (DENV), are well characterised, yet rapid climate change, land-use shifts, and urbanisation necessitate current surveillance, especially where humans and animals overlap. Seven interfaces, houses ( n = 9), temples ( n = 2), dumpsites ( n = 6), orchards ( n = 8), forest edges ( n = 9), forest interior ( n = 9) and bat caves ( n = 2), were sampled in dry and wet seasons of 2024 to determine mosquito species presence and abundance in four districts: Pong Nam Ron (PNR) and Soi Dao (SD) in Chanthaburi province, Mae Fah Luang (MFL) and Wiang Kaen (WK) in Chiang Rai province. Snapshot sampling deployed 2–3 daily replicates of multiple trap types (Light traps, Biogents Pro traps, Gravid Aedes traps, and Prokopack aspirators) over 48 h per interface. Mosquito presence/absence and abundance across interfaces and seasons were assessed with GLMMs, with Tukey post hoc tests. Rarefied diversity indices were calculated for host-seeking communities at interfaces. Overall, dumpsites had the highest burden of arboviral vector species. Culex gelidus (45.6%, n = 6,195) and Culex vishnui (24.6%, n = 3,348) were the two most abundant vectors and were most prominent at dumpsites. Aedes albopictus (9.0%, n =1,014) was the third top vector, found across all interfaces with high abundances in forests in all districts and at the MFL dumpsite. Host seeking communities at dumpsites were consistently low in diversity as were forest interiors in PNR and WK. This is the first investigation of arboviral vector ecology in Thailand to include dumpsites. These sites support high populations of mosquito vectors that feed day and night, and attract animal species presenting a zoonotic risk to workers and neighbouring farmland communities. Forest sites were also high-risk settings owing to Ae. albopictus predominance. Further investigation into its potential as a bridge vector and role in sylvatic transmission is required. Longitudinal monitoring of rural interfaces is recommended to inform vector control and One Health preparedness.