[Culicidae (Diptera) in a dam construction area in the state of São Paulo, Brazil].

Objective: To describe the culicidae fauna in an area impacted by environmental changes caused by the construction of a dam.

Methods: The studied area was the Porto Primavera dam construction site in Southeastern Brazil. Monthly culicidae samples were taken in six exploratory sites in the pre-filling period and in one fixed site, one year before (1997-1998) and after the first filling (1999-2000). Adult mosquitoes were captured in the morning with an aspirator and with Shannon and CDC traps during the evening twilight period. Immature stages were captured using a ladle in the larger breeding sites and with a pipette in the smaller ones.

Results: In the pre-filling period of the dam, a total of 944 immature culicidae specimens, from ten species, were captured. A total of 14,932 adults were captured, including 7,031 mosquitoes from ten species in the exploratory points and 7,901 specimens from eight genera in the fixed site. After the first stage of the dam filling, the immature stages total was 1,201, from four genera, and the captured mosquitoes total was 5,912, from nine genera. There was a population reduction of the genera Aedes and Psorophora and an increase of the following species populations: Aedeomyia, Anopheles, Culex (Melanoconion), Mansonia and Uranotaenia.

Conclusions: The environmental changes caused due to the construction of the Porto Primavera Dam contributed to an increase in the population density of some culicidae vectors, causing a nuisance and the potential risk of the transmission of pathogens to humans.