Selection of Bacillus thuringiensis Berliner strains to control Aedes aegypti Linnaeus

The present study aimed to select strains of Bacillus thuringiensis with insecticidal activity against Aedes aegypti. It was tested sixteen strains of bacteria, isolated from Paraná state, Brazil, that were used in laboratory assays with mosquito larvae. Tests were carried out in two stages, first one to select the most efficient strains (screening) and second to estimate LC50. The protein profile of the highest toxicity of strain was obtained by SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis). The best performance of larval mortality was produced by BR-01 strain, which 96.7% mortality rate, significantly higher than others. In the second part, there was obtained a LC50 of 9.07 µL.L-1 fermented extract. The protein profile revealed many peptides between 15 and 140kDa, similar to that reported in Bacillus thuringiensis ser. israelensis strains which high toxicity to mosquito species.O presente trabalho buscou selecionar cepas de Bacillus thuringiensis com atividade inseticida contra Aedes aegypti. Foram testadas 16 estirpes da bactéria provenientes do estado do Paraná, Brasil, que foram utilizadas em ensaios laboratoriais com larvas do culicídeos. Os testes foram realizados em duas etapas, a primeira com a seleção de cepas e a segunda para estimar a CL 50 das cepas com melhores resultados. O perfil protéico do isolado de maior toxicidade foi obtido por SDS-PAGE (dodecil sulfato de sódio –eletroforese em gel de poliacrilamida). O melhor resultado de mortalidade foi produzido com a cepa BR-01, que produziu 96,7% de mortalidade de A. aegypti, valor significativamente superior aos demais. Na segunda fase, obteve-se CL50 de 9,07 μL.L -1 de extrato fermentado. O perfil protéico revelou peptídeos entre 15 e 140 kDa, resultado semelhante ao relatado nas cepas de Bacillus thuringiensis var. israelensis de maior toxicidade às espécies de culicídeo

Genetic variability of populations of Nyssomyia neivai in the Northern State of Paraná, Brazil

The genetic study of sandfly populations needs to be further explored given the importance of these insects for public health. Were sequenced the NDH4 mitochondrial gene from populations of Nyssomyia neivai from Doutor Camargo, Lobato, Japira, and Porto Rico, municipalities in the State of Paraná, Brazil, to understand the genetic structure and gene flow. Eighty specimens of Ny. Neivai were sequenced, 20 from each municipality, and 269 base pairs were obtained. A total of 27 haplotypes and 28 polymorphic sites were found, along with a haplotypic diversity of 0.80696 and a nucleotide diversity of 0.00567. Haplotype H5, with 33 specimens, was the most common among the four populations. Only haplotypes H5 and H7 were present in all four populations. The population from Doutor Camargo showed the highest genetic diversity, and only this population shared haplotypes with those from the other municipalities. The highest number of haplotypes was sheared with Lobato which also had the highest number of unique haplotypes. This probably occurred because of constant anthropic changes that happened in the environment during the first half of the twentieth century, mainly after 1998. There was no significant correlation between genetic and geographical distances regarding these populations. However, the highest genetic and geographical distances, and the lowest gene flow were observed between Japira and Porto Rico. Geographical distance is a possible barrier between these municipalities through the blocking of haplotype sharing

Low Gene Flow of Aedes aegypti between Dengue-Endemic and Dengue-Free Areas in Southeastern and Southern Brazil

International audienceWe present a population genetic study of Aedes aegypti in Brazil using isoenzyme markers. Four poly-morphic loci were used to examine 11 mosquito collections at four periods in 2003. Samples from a dengue-endemic area (southeastern region) and a dengue-free area (southern region) connected by an important network of roads and railways were analyzed. The degree of genetic differentiation observed between populations is consistent with limited gene flow between them. There was no evidence of passive dispersion of Ae. aegypti by vehicles among the different routes linking metropolitan areas

Higher genetic variation estimated by microsatellites compared to isoenzyme markers in Aedes aegypti from Rio de Janeiro

Aedes aegypti populations from five districts in Rio de Janeiro were analyzed using five microsatellites and six isoenzyme markers, to assess the amount of variation and patterns of gene flow at local levels. Microsatellite loci were polymorphic enough to detect genetic differentiation of populations collected at small geographic scales (e.g. within a city). Ae. aegypti populations were highly differentiated as well in the city center as in the outskirt. Thus, dengue virus propagation by mosquitoes could be as efficient in the urban area as in the outskirt of Rio de Janeiro, the main entry point of dengue in Brazil