Problem statement: The dammed up area is an artificial imposition that has caused changes to the natural fauna and flora. The resultant expansion of the Selva Marginal Paranaense del Paraná, which starts in Brazil, increases the possibility of risks of new breeding grounds for the carriers of illnesses such as Malaria, Dengue and Yellow Fever.

Methods: Monitoring started in the area in 1993 and the observations that are mentioned cover the period 2000-2001. The sample stations are located between the Provincia de Corrientes, Argentina in the west and Paraguay in the east. Adult mosquitoes were caught monthly, with parallel traps. One CDC bag had a sleeve and another had alcohol for 24 hours in each station. The study was complemented with the collection of larvae and the collection of adults with human fat (sebo) in areas close to the traps. The captured samples formed part of the reference collection, which permitted comparisons with future samples. These determinations at the generic and specific level formed part of the published taxonomic keys, descriptions and revisions covering the fauna of South America for different scientific magazines and books for universities, research institutions and national and international health organisations.

Outcomes and impact: Variation in the composition and behaviour of the fauna of dipterous hematofagos is fundamental for the prevention of both the increased risk and occurrence of contagious the human illnesses. The current procedures used in evaluating the impact of certain species and the actions needed to mitigate them, stress the importance of the correct taxonomic determination of the fauna. What is important to note, however, is that of the 58 species of mosquitoes found, only 5 were of proven epidemiological value in the region. It is towards these species that efforts of monitoring and control measures need to be directed.

Lessons: The monitoring on the Argentinean side of the Rio Parana revealed 13 species and 58 specimens of the Culicidae family. The taxonomic determinations that stood out were: Anopheles darlinghi and A. albitarsis, carriers of malaria in the study area, an illnesses which is an epidemic in the region; Aedes aegypti, carrier of dengue and yellow fever; Haemagogus leucocelaenus, carrier of yellow fever in the forests; and Culex pipiens, the carrier of filariasis in this region and secondary carrier of yellow fever in the Old World. By identifying the carriers of the epidemic diseases and focussing monitoring and control programmes on these, unnecessary control programmes for other species in the region can be avoided.