Biologia comparada de populações de Lutzomyia umbratilis (diptera: psychodidae) da amazônia central brasileira

Lutzomyia umbratilis Ward & Fraiha (Diptera: Psychodidae) is the main phlebotomine sand fly vector of cutaneous leishmaniasis due to Leishmania guyanensis Floch (Kinetoplastida: Trypanosomatidae) in northern South America. Populations of L. umbratilis naturally infected by Leishmania guyanensis can be found east of the Rio Negro and north of the Rio Amazonas. South of the Amazon river system, only natural infections by trypanosomatids other than Leishmania have been reported in L. umbratilis. With the aim of detecting possible geographical variations in natural populations of L. umbratilis separated by the Negro-Amazonas system, the present work integrated morphologic and molecular studies. Sand fly catches were done in the state of Amazonas: Manaus, Pitinga, Manacapuru and Novo Airão. A total of 46 morphologic characters of 40 fourth instar larvae of each population were measured, and the data were analyzed by univariate and multivariate analyses. The results showed highly significant differences among the populations. The chaetotaxy and description of the pupa of L. umbratilis was accomplished. Characters of the armature of the genital atrium of adults from Manacapuru and Manaus were compared, showing slight qualitative differences, and significant differences in relation to the size of the spines. Through conventional coloration the polytene chromosome was observed, but the bands could not be analyzed, and the kariotype was shown to be 2n=6. A total of 300 specimens of each population were used for the isoenzyme analyses, and 12 enzymatic systems were tested in starch gel and starch-agarose with specific buffers and staining. The analysis of 10 enzymatic loci showed that the allelic frequencies did not demonstrate significant differences, and the proportion of polymorphic loci were the same among the populations. The results of the coefficient F of Wright showed that all the loci presented low genic structuring. The genetic distance was very close among the populations, suggesting that they are homogeneous. Additional studies using other genetic markers and morphometric characters should be considered in the future in order to confirm the existence of geographical variations among these populations.Lutzomyia umbratilis ) Ward & Fraiha (Diptera: Psychodidae é o principal flebotomíneo vetor de leishmaniose tegumentar devido a Leishmania guyanensis Floch (Kinetoplastida: Trypanosomatidae) ao norte da América do Sul. Populações de L. umbratilis infectadas naturalmente por Leishmania guyanensis podem ser encontradas ao leste do Rio Negro e ao norte do Rio Amazonas. Ao sul do sistema fluvial do Rio Amazonas, somente infecções naturais por tripanosomatídeos não-leishmanióticos têm sido registradas. Visando detectar possíveis variações geográficas em populações naturais de L. umbratilis separadas pelo sistema fluvial Negro-Amazonas, o presente trabalho teve como objetivo principal integrar estudos de taxonomia morfológica e molecular. As coletas foram realizadas no estado do Amazonas: Manaus, Pitinga, Manacapuru e Novo Airão. Foram medidos 46 caracteres morfológicos de 40 larvas de quarto estádio de cada população, e os dados analisados através de análise univariada e multivariada. Os resultados mostraram diferenças altamente significantes entre as populações. Foi realizado a quetotaxia e a descrição da pupa de L. umbratilis. Caracteres da armadura do átrio genital de adultos de Manacapuru e Manaus foram comparados, mostrando ligeiras diferenças qualitativas, e diferenças significantes em relação ao tamanho dos espinhos. Mediante coloração convencional o cromossomo politênico foi evidenciado, mas sem condições de análise das bandas, e o cariótipo com 2n=6 foi observado. Nas análises de isoenzimas foram utilizados 300 espécimes de cada população. Foram testados 12 sistemas enzimáticos em gel de amido e amido-agarose com tampões e coloração específica. A análise de 10 locos enzimáticos mostrou que as freqüências alélicas não demonstraram diferenças significativas, a proporção de locos polimórficos foi igual nas populações. Os resultados do coeficiente F de Wright mostraram que todos os locos apresentaram baixa estruturação gênica. A distância genética foi muito próxima entre as populações, sugerindo que sejam homogêneas. Estudos utilizando outros marcadores genéticos e caracteres morfométricos devem ser realizados a fim de discriminar em mais detalhes as variações geográficas entre essas e outras populações de L. umbratilis

Trypanosoma cruzi discrete typing unit TcIV implicated in a case of acute Chagas disease in a domiciliated dog in the western Amazon

Chagas disease is caused by the protozoan Trypanosoma cruzi. Seven lineages have been identified based on different molecular markers, namely TcI, TcII, TcIII, TcIV, TcV, TcVI, and TcBat. Dogs play the role of epidemiological sentinels being domestic reservoirs of T. cruzi. The aim of the current study was to report the first case of CD in a domestic dog in Manaus, Amazonas, Brazil, infected with T. cruzi DTU TcIV. We hope our report encourages veterinarians and surveillance professionals to a take a deeper look at T. cruzi infection in domestic animals.publishersversionpublishe

Biodefensive Based on <i>Piper nigrum</i> Essential Oil for Controlling of <i>Anopheles aquasalis</i> Larvae: Influence of Temperature (35 °C) and Preservatives

Considerable efforts have been spent on the development of biodefensives based on the encapsulation of essential oils for controlling of urban pests from their larval stage, especially as anopheline controlling agents. The larval source management of Anopheles aquasalis is important for malaria prevention. For this reason, this research proposes larvicidal biodefensives based on polymeric particles loaded with Piper nigrum essential oil, considering the influence of temperature (35 °C) and preservatives on the formulation stability. The biodefensive containing the preservative phenoxyethanol/methylisothiazolinone (PNE) resulted in 5 months of shelf-life storage with an Encapsulation Efficiency (EE%) of essential oil of 70%. The biodefensive PNE (containing 500 µg.mL−1 of encapsulated essential oil) presented a polydisperse particle size distribution, ranging from D10 = (127 ± 10) nm to D90 = (472 ± 78) nm and a particle mean size of (236 ± 34) nm. The AFM images revealed a spherical morphology with an external surface almost regular and smooth. The controlled release of the essential oil was evaluated up to 72 h according to the Korsmeyer-Peppas mathematical model, confirming the anomalous transport (n = 0.64 in pH = 3 and pH = 10, and n = 0.65 in pH = 7). The total larvae mortality on the in loco bioassays was almost reached (92%) after 24 h. However, according to the in vitro bioassays applying the in natura essential oil alone, the concentration of 454 μg.mL−1 resulted on the mortality of 70% of the larvae after 24 h. For this reason, the highest efficiency of the biodefensive PNE may be related to the encapsulation of essential oil, delivering the loaded particles more efficiently inside the larvae. From this perspective, the present study shows that a formulation based on P. nigrum essential oil may be taken into account in the integrated management of disease vector mosquitoes