Molecular exploration of mosquitoes and their vector-borne pathogens in urban water environments in Benin

Malaria and dengue fever, both transmitted by mosquitoes, are major health concerns in (sub)tropical regions, with expanding endemic ranges. Monitoring mosquito populations and the pathogens they carry is crucial for effective vector control. Here, we explored molecular-based surveillance using environmental water samples as an alternative to conventional mosquito collection methods. A total of 154 samples were collected from eight environment types, including septic tanks, urban drainage, lake, groundwater, puddles, and tire tracks, in urban Benin. Polymerase chain reaction and high-throughput sequencing were used to detect gene fragments of mosquitoes and pathogens such as dengue virus and Plasmodium spp., a group of parasitic protozoa that cause malaria. The presence of DNA from several medically important mosquito species, including Aedes aegypti, Anopheles gambiae, Culex pipiens or Cx. quinquefasciatus, Cx. tritaeniorhynchus, and Mansonia africana, was identified in 12 samples from urban drainage, lake, groundwater, and tire tracks. However, neither dengue virus nor Plasmodium was found. These findings highlight both the potential and current limitations of environmental DNA for mosquito and pathogen surveillance. Improving primer specificity and refining sequencing protocols will be necessary to improve sensitivity and reliability. Despite these limitations, this approach offers a promising non-invasive approach that does not require mosquito capture and can complement traditional mosquito monitoring to strengthen vector control programs.