Anopheline diversity, ace-1 resistance and climate-driven habitat projections for Anopheles peditaeniatus in Lao PDR border regions

Over the past two decades, the Lao People’s Democratic Republic (Lao PDR), one of the Greater Mekong Subregion (GMS) countries, has made remarkable progress in malaria control, but heterogeneous transmission, insecticide resistance, cross-border parasite importation and climate-driven vector habitat shifts still hinder malaria elimination. Systematic studies on species composition, insecticide resistance and habitat suitability of Anopheles mosquitoes are essential for targeted interventions. Mosquitoes were overnight collected using battery-operated CDC light traps at four transboundary sites across Laos, Cambodia and Thailand from 2017 to 2019. Species identification was conducted by combining cytochrome c oxidase subunit 2 (COII) and internal transcribed spacer 2 (ITS2) sequencing. Insecticide resistance profiles were evaluated via targeted sequencing of the knockdown resistance ( kdr , L1014F) and acetylcholinesterase-1 ( ace-1 , G119S) loci. Maximum Entropy Model (MaxEnt) ecological niche modeling was employed to predict habitat suitability for Anopheles peditaeniatus using 108 occurrence points and 19 bioclimatic variables from WorldClim version 2.1 at a spatial resolution of 2.5 arc minutes (baseline climate: 1970–2000; future projections: 2021–2040 under various Shared Socio-economic Pathway (SSP) scenarios, derived from the Beijing Climate Center Climate System Model version 2-Medium Resolution (BCC-CSM2-MR) global climate model. Fifteen Anopheles species were identified, with An. kochi (38.46%) and An. sinensis (21.69%) being the dominant species. Among the 18 collected An. peditaeniatus individuals, ace-1 genotyping revealed that 5 were homozygous susceptible (GG) (27.8%), 12 were heterozygous carriers (GS) (66.7%), and 1 was homozygous resistant (SS) (5.6%), while no kdr L1014F mutations were detected in any of the tested species. MaxEnt models showed good performance, with BIO6 (Min Temperature of Coldest Month), BIO18 (Precipitation of Warmest Quarter), and BIO4 (Temperature Seasonality) acting as the key climatic drivers. Under the SSP245, SSP370 and SSP585 scenarios, highly suitable habitats for An. peditaeniatus expanded markedly in the tri-border region; SSP126, by contrast, induced habitat fragmentation, with core suitable areas confined to major wetlands. Molecular and morphological identification of 650 Anopheles specimens identified 15 species whose assemblages displayed marked spatial heterogeneity across the four sampling sites; the overall mosquito community was predominated by An. kochi (38.5%) and An. sinensis (21.7%). The high frequency of the ace-1 G119S mutation in An. peditaeniatus (one of the Anopheles hyrcanus group) highlights the necessity of tailored insecticide rotation strategies to mitigate resistance development. MaxEnt modeling projections pinpoint future hotspots of vector activity for this species. Incorporating these insights into cross-border surveillance systems and targeted intervention measures will enhance malaria elimination efforts amid climatic changes and persistent insecticide resistance threats in the GMS.