Problem statement: Yacyretá is a man-made reservoir, begun in 1996, covering approximately 1,600 square km. It is situated on the Río Paraná between Argentina and Paraguay, and supplies a hydroelectric powerplant that generates electricity for these countries. The reservoir has significantly affected the natural fauna and flora of the region, and the resultant expansion of the adjoining marginal forest from Brazil (Selva Marginal Paranaense del Paraná) could create new breeding grounds for the particular species of mosquito that carry illnesses such as malaria, dengue and yellow fever.

Methods: Monitoring of mosquitoes began in 1993. Sampling stations were located on both the Argentina and Paraguay sides of the reservoir. Adult mosquitoes and larvae were also collected monthly. The captured specimens were added to a reference collection. Results of the monitoring and associated taxonomic research including identification of specimens to genus and species level was published in taxonomic keys, descriptions and revisions in scientific journals and books for universities, research institutions and national and international health organisations.

Outcomes and impact: The study identified 13 genera and 58 species of the Culicidae family for the Argentinean side of the Rio Parana. Of the 58 mosquitoe species, five were proven to be disease carriers of epidemiological significance in the region: Anopheles darlinghi and A. albitarsis, both carriers of malaria, Aedes aegypti, a carrier of dengue and yellow fever, Haemagogus leucocelaenus, a carrier of yellow fever, and Culex pipiens, a carrier of filariasis and secondary carrier of yellow fever.

Lessons: In areas subjected to significant land use changes, expert taxonomic identifications and reference collections of disease carrying and related species are needed to evaluate changing risks and target monitoring and control programmes. Accurate knowledge of current disease vector distributions avoids unnecessary control programmes for other similar but benign species.