Isolation and genetics of populations of genes associates to the resistance the insecticides in Lutzomyia longipalpis (Lutz e Neiva, 1912) (Diptera: Psychodidae: Phlebotominae), vector of the American Visceral Leishmaniasis.
Sandflies are the vectors of leishmaniasis and Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae) is the main vector of Leishmania infantum chagasi, thecausative agent of American Visceral Leishmaniasis (AVL). Because of its importance as a vector, several studies have been carried out to verify the real taxonomic status of L.longipalpis and the existence of cryptic sibling species among Brazilian populations is still a controversial issue. Fragments of three genes associated with insecticide resistance wereisolated: paralytic (para), Acetylcholinesterase (Ace) and Resistant to dielrin (Rdl). In addition, a region of the para gene were many pyrethroid and DDT resistance mutations occurin other insect species, was used as a molecular marker to study Brazilian populations of L. longipalpis and to investigate the occurrence of mutations potentially associated withinsecticide resistance in this vector. Samples from the Brazilian localities of Sobral (CE), Pancas (ES), Lapinha (MG), Jacobina (BA), Estrela de Alagoas (AL) and Nisia Floresta,Great Natal (RN) were analyzed. The results obtained with the para gene support previous results showing that in Sobral L. longipalpis males carrying one (1S) and two (2S) abdominalspots belong to two sympatric sibling species. The occurrence of fixed differences in the studied gene fragment between the two types of males makes para a very useful molecularmarker to identify females of these two species in future studies. Data presented here also suggests that Pancas, Sobral 2S and Natal belong to the same sibling species, while Sobral 1S,Lapinha, Jacobina and Estrela 1S probably represent four other sibling species in Brazil. These results are in agreement with previous studies using other molecular markers, crossingexperiments, pheromone and copulation song analysis, and strongly support the existence of a species complex among Brazilian populations of L. longipalpis. The present study alsorepresents the first analysis of insecticide resistance genes in this important leishmaniasis vector.
Advisor:Alexandre Afranio Peixoto
School:Faculdades Oswaldo Cruz
Source Type:Master's Thesis
Keywords:Psychodidae Lutzomyia longipalpis Leishmaniasis Visceral Insecticide Resistance
Date of Publication:07/14/2006