The presence of mosquitoes (Diptera: Culicidae) in flood containment reservoirs in the eastern region of the City of Sao Paulo, Brazil

Introduction: Alterations in the environment contribute to changes in weather patterns, which cause an increase in rainfall, which causes flooding. Flooding has been addressed by building reservoirs, called piscinoes, to contain the excess rain. In this report, we evaluated the Culicidae fauna of epidemiological importance in the reservoirs of Caguacu and Inhumas. Methods: Monthly collections were performed in both reservoirs, which are situated in the eastern section of the city of Sao Paulo. Monthly collections of Culicidae were undertaken using the entomological scoop method and a battery aspirator during the period between March 2006 and February 2007. Descriptive statistical and simple linear regression analyses of the data were carried out. Results: A total of 8,917 Culicidae mosquitoes were collected. The majority of the insects captured were of Culex (Culex) quinquefasciatus, representing 98.9% of the specimens identified in the Inhumas and 95.2% of those identified in Caguacu. In the Caguacu reservoir, the greatest frequency of immature mosquitoes was observed in the spillway (61%). In the Inhumas reservoir, the greatest occurrence of immature Culicidae was detected in the channel (42.6%). The linear regression analysis showed that 87% of the larvae in the third and fourth stages and 60% of the pupae were collected during periods of rainfall. In the Inhumas reservoir, 36% of the larvae and 18% of the pupae were collected during periods of rainfall. Conclusions: Culex quinquefasciatus, a vector for agents of filariasis and arbovirus diseases and a nuisance to the human population, was frequent in both environments. Methods of control of the species in the studied dams are necessary to reduce their epidemiological potential.