Nationwide larval mosquito sampling in Cambodian households: Vector species in anthropogenic breeding sites

Vector control remains a key strategy in reducing mosquito-borne disease transmission. Understanding mosquito species distribution, diversity, and breeding habitat ecology is crucial for effective surveillance and to define targeted vector control interventions. We conducted a study to understand the diversity and habitat preferences of mosquito larvae across Cambodia during the rainy season from July to September 2024. Mosquito larvae were collected from a variety of breeding habitats located around households across all 25 provinces. The national sampling was conducted once during the rainy season in urban (city) and rural (village) areas within each province. Collected larvae were reared to adult emergence in the insectarium for morphological identification, further confirmed with molecular techniques. We found 37 mosquito species in the households, of which 12 are vectors of pathogens such as dengue and Japanese encephalitis viruses, and Plasmodium species, representing 93% of all collected mosquitoes. Larvae were predominantly found in anthropized artificial breeding habitats, accounting for 98% of all larvae collected. Notably, the two primary dengue vectors, Aedes aegypti and Ae. albopictus, were recorded from all 52 sampling locations. In addition, our study identified the presence of Aedes vittatus in 12 provinces, a new confirmed vector of dengue in Cambodia. We also recorded eight Japanese encephalitis vectors, with at least one species from all sampling sites. There were no statistically significant differences in larval mosquito biodiversity (relative abundance, number of species, Shannon and Simpson diversity indices) between cities and villages, with 15 species occurring in both environments, representing 41% of the species and 99% of all mosquitoes collected. The widespread and predominant presence of dengue and Japanese encephalitis vectors in every household confirms the endemic circulation of these diseases in Cambodia.