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Populations of Culex quinquefasciatus (Diptera: Culicidae) from the State of São Paulo: comparative analyses based on ribosomal DNA, geometric morphometry and egg micrography

Grant number: 07/01665-5
Support type:Scholarships in Brazil - Master
Effective date (Start): September 01, 2007
Effective date (End): March 31, 2009
Field of knowledge:Biological Sciences - Parasitology
Principal Investigator:Lincoln Suesdek Rocha
Grantee:Camila Moratore
Home Institution: Instituto Butantan. Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

The dipteran Culex quinquefasciatus is among the species of Culicidae of medical importance. This species is a vector of bancroftian filariasis in Neotropics and may be vector of arbovirus in several countries, as for example, the West Nile Virus, the aethiological agente of a severe encephalitis. This mosquito has synanthropic habits, is capable of living in polluted areas in the cities, and may develop resistance to some inseticides. Owing to its medical relevance of Cx. quinquefasciatus, several attempts of elimination and populational control have been tried. In general, a limiting factor to such methods is the microevolutionary processes of insects, through which biological aspects of a species evolve in short intervals of time and space. Hence, microevolutionary studies are a central issue in medical entomology. Microevolutionary studies usually begin by populational characterization throughout geographical transects. As with other culicids of medical importance, population genetics, populational differentiation, and insecticide tolerance of Cx. quinquefasciatus has been studied in many regions of the world. Nevertheless, such studies involving Cx. quinquefasciatus are quite scarce in Brazil. In the State of São Paulo, there are some occurrences of Cx. quinquefasciatus which should be investigated with attention.In an important touristical point of São Paulo county, the Parque Ecológico do Tietê (P.E.T.), the species is very abundant and inconvenient for thousands of tourists and inhabitants of that region. Furthermore this urban park houses several species of autoctonous and migrating vertebrates, which are potential hosts of ethiological agents of zoonoses vectored by mosquitoes.In another county of the state of São Paulo, Pariquera-Açu (~150km away from the capital), where the culicidofauna is quite well known the species is also abundant, inconvenient for humans and sometimes inconvenient for cows and other animals. This region is particularly interesting since it comprises urban, semi-urban and rural areas near to “Altantic forest” ecosystem. Since this locality is ecologically peculiar, it is possible that it houses culicid populations with peculiar biological characters as well.The counties of São Paulo and Pariquera-Açu are, thus, regions of great culicidological relevance, not to mention that they are ecologically quite distinct and geographically distant. It is still unknown whether there are genetic/morphological differences or gene flow between those two localities or not. In order to test these hypotheses, the two populations will be compared through different biological tools, which are so far admittedly useful in populational characterization: a) aspects within the ribosomal DNA; b) wing morphometrics; c) egg micrography. We aim to identify biological variations that may have any evolutionary importance for this species, which could contribute to improvement of populational control methods.