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Study of ecological parameters of Culicids found in wooded nature reserves and in urban areas of São José do Rio Preto, São Paulo State, Brazil

Grant number: 06/00360-3
Support type:Regular Research Grants
Duration: July 01, 2006 - January 31, 2008
Field of knowledge:Biological Sciences - Parasitology
Principal Investigator:Margareth Regina Dibo
Grantee:Margareth Regina Dibo
Home Institution: Superintendência de Controle de Endemias (SUCEN). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

West Nile Fever is a viral zoonotic disease transmitted by vectors that infect birds, mosquitoes and mammals, including man. The symptoms in humans are similar to influenza with fever, but acute meningitis and encephalitis can occur; fatal cases are related to over fifty-year-olds. The virus is transmitted by arthropods of the Culicidae family, in particular of the Culex genera, although it has been detected in Aedes, Ochlerotatus, Anopheles and Psorophora. Given that São José do Rio Preto is situated on the flight path of migrating birds, it is important to know the diversity of culicids that exist in wooded areas of the municipal as well as to investigate a possible contact between the dominant or most common species human settings during the months of the year. Culex quinquefasciatus is very common in urban areas and generally has a high density which highlights the importance of evaluating breeding places of this species in these surroundings. Objectives. To measure the diversity of the species of adult culicids found in wooded nature reserves in the municipal; to describe the seasonal variations of the dominant culicid species found in these reserves and to associate this with the climate conditions. Other objectives include to measure the abundance of larva from the species of Culex genera found in the urban area and to describe the seasonal variations of these larva. Methods. The study will be carried out in four wooded areas in the municipal and in some places of the urban area established as breeding places for the Culex genera. Collections of adult culicids from wooded areas will be made using five CDC-type light traps installed at equal distances along a straight line and turned on for 12-hour periods. Larva will be collected, in urban areas, from a systematic sample of breeding points. Both activities will be made once per month over one year. The specimens will be identified in the laboratory. Thermohygrometers will be installed in each wooded area and the rainfall will be obtained through the Department of Agriculture. All the information will be entered in a database using the Excel Program and the statistical analysis will be achieved using the SPSS Program version 11.0.The diversity will be measured using two methods: quantification of the number of species in the woods (richness) and the structure of the culicid community based on dominance and equitability of the individuals, enabling a comparison between areas. The variation of seasonal activity of each of the species of dominant adult culicids and their comparison in the wooded areas will be verified using the Williams’ average. The correlation of adult mosquitoes of each of the dominant species with the rainfall, the temperature and the humidity will be checked using the correlation coefficient. The effect of precipitation, temperature and humidity variables in respect to the abundance of mosquitoes will be verified using Linear Regression or Generalized Estimation Equation models depending on the normality of the data. The abundance of larva belonging to the Culex genera will be calculated in the urban area using their absolute and relative frequencies. The percentage of larva obtained for each of the species according to the months of the year with their respective 95% confidence intervals will be presented. (AU)