Study of karyotype and constitutive heterochromatin of Mansonia spp. (Diptera: Culicidae) in the area surrounding the Jirau Hydroelectric Dam, Rondônia, Brazil

ABSTRACT Background: Mansonia mosquitoes transmit arboviruses to humans. This study describes the karyotypes and C-banding of Mansonia humeralis, Mansonia titillans, Mansonia pseudotitillans, and Mansonia indubitans. Methods: From the 202 larvae, the brain ganglia were dissected (n=120) for the preparation of slides. Twenty slides with well-distended chromosomes for each species (10 for karyotyping and 10 for C-banding) were selected for further study. Results: The haploid genome and the average lengths of the chromosomal arms differed in relation to the centromere between species, and intraspecific differences also occurred in the distribution of the C-bands. Conclusions: These results are useful for better understanding of the chromosomal variability of Mansonia mosquitoes.

Endophytic fungus Phomopsis sp. as a source of 3-nitropropionic acid with larvicidal activity against Aedes aegypti (Linnaeus 1762, Diptera: Culicidae)

ABSTRACT Background: Aedes aegypti is the primary vector of viruses, such as Zika, chikungunya, yellow fever, and dengue. In this context, a biomonitored chemical study was conducted to evaluate the activity of the crude extract of the endophytic fungus Phomopsis sp. against the larvae of Aedes aegypti. Methods: Crude extract, fractions, and isolated substances were evaluated in in-vitro assays against third-stage larvae of Aedes aegypti. Results: We isolated 3-nitropropionic acid with an LC50 of 15.172 ppm and LC90 of 18.178 ppm after 24 hours of larval exposure. Conclusions: The results indicated that 3-nitropropionic acid exerted larvicidal activity.

Oxidative stress induction by crude extract of Xylaria sp. triggers lethality in the larvae of Aedes aegypti (Diptera: Culicidae)

ABSTRACT Background: Aedes aegypti is currently controlled with synthetic larvicides; however, mosquitoes have become highly resistant to these larvicides and difficult to eradicate. Studies have shown that insecticides derived from fungal extracts have various mechanisms of action that reduce the risk of resistance in these mosquitoes. One possible mechanism is uncontrolled production of reactive oxygen species (ROS) in the larvae, which can cause changes at the cellular level. Thus, the crude extract of Xylaria sp. was evaluated to investigate the oxidative effect of this extract in A. aegypti larvae by quantifying the oxidative damage to proteins and lipids. Methods: The larvicidal potential of the crude extract of Xylaria sp. Was evaluated, and the extract was subsequently tested in human lung fibroblasts for cytotoxicity and ROS production. ROS level was quantified in the larvae that were killed following exposure to the extract in the larvicide test. Results: The crude extract of Xylaria sp. Caused cytotoxicity and induced ROS production in human lung fibroblasts and A. aegypti larvae, respectively. In the larvicide trial, the extract showed an LC50 of 264.456 ppm and an LC90 of 364.307 ppm, and was thus considered active. The extract showed greater oxidative damage to lipids and proteins, with LC90 values of 24.7 µmol MDA/L and 14.6278 ×10-3 nmol carbonyl/ mg protein, respectively. Conclusions: Crude extracts of Xylaria sp. induced oxidative stress that may have caused the mortality of A. aegypti larvae.

Do climate changes alter the distribution and transmission of malaria? Evidence assessment and recommendations for future studies

Abstract Malaria, a mosquito-borne infectious disease, is considered a significant global health burden. Climate changes or different weather conditions may impact infectious diseases, specifically those transmitted by insect vectors and contaminated water. Based on the current predictions for climate change associated with the increase in carbon dioxide concentrations in the atmosphere and the increase in atmospheric temperature, the Intergovernmental Panel on Climate Change predicts that in 2050, malaria may threaten some previously unexposed areas worldwide and cause a 50% higher probability of malaria cases. Climate-based distribution models of malaria depict an increase in the geographic distribution of the disease as global environmental temperatures and conditions worsen. Researchers have studied the influence of changes in climate on the prevalence of malaria using different mathematical models that consider different variables and predict the conditions for malaria distribution. In this context, we conducted a mini-review to elucidate the important aspects described in the literature on the influence of climate change in the distribution and transmission of malaria. It is important to develop possible risk management strategies and enhance the surveillance system enhanced even in currently malaria-free areas predicted to experience malaria in the future.

Characterization of artificial larval habitats of Anopheles darlingi (Diptera: Culicidae) in the Brazilian Central Amazon

ABSTRACT Mosquitoes belonging to the Anopheles genus are of great relevance in the epidemiology and transmission of malaria, with their larval phase developing in clean waters in the presence of organic matter. However, the human presence in the Amazon has increasingly influenced the emergence of new breeding sites and larval habitats, such as clay pits, fish ponds and dams, among others. The objective of the study was to characterize mosquito larval habitats using the biotic and abiotic parameters in the metropolitan area of Manaus. We collected in 23 artificial larval habitats in Manaus, classified in dams, fish ponds and clay pits. Water samples, Anopheles larvae, aquatic macrophytes and limnological parameters were collected from each artificial larval habitat. The Larvae Index per Man/Hour and canonical correspondence analysis were used for data analysis. Results indicate that artificial larval habitats with characteristics similar to natural sites present higher larval density, displaying a high abundance of An. triannulatus and An. darlingi. More than 90% of the determined limnological parameters were in agreement with the environmental resolution stipulated by the Brazilian environmental resolution, while pH, dissolved oxygen and phosphorus levels were below the established limits at some of the larval habitats. Conductivity, total suspended solids and phosphorus were positively correlated to the presence of An. albitarsis, An. peryassui and An. nuneztovari in fish ponds, and An. trianulatus and An. braziliensis in dams. Thus, the evaluated limnological variables and habitat structure explain Anopheles species distribution in artificial larval habitats in the metropolitan Manaus region.

Oviposition of Aedes aegypti Linnaeus, 1762 and Aedes albopictus Skuse, 1894 (Diptera: Culicidae) under laboratory and field conditions using ovitraps associated to different control agents, Manaus, Amazonas, Brazil

ABSTRACT The aim of this study was to analyze the effectiveness of different control agents of Aedes aegypti and Aedes albopictus associated with ovitraps under laboratory and field conditions. Five treatments were used: grass infusion + Bacillus thuringiensis israelensis (gI + Bti), grass infusion + Saccharopolyspora spinosa (gI + Ss), grass infusion + Pyriproxyfen (gI + P), distilled water + Toxorhynchites haemorrhoidalis (dW + Th), and grass infusion (gI) (control). The highest mean number of eggs of both species were obtained with grass infusion in the laboratory. Among control agents, the lowest mean of A. aegypti eggs occurred with gI + Ss and the lowest mean of A. albopictus eggs occurred with dW + Th. There was no difference between treatments in A. aegypti (P = 0.4320) and A. albopictus (P = 0.7179). In the field, the highest mean number of eggs for both species were obtained with gI + Ss, and the lowest values were obtained with gI + P (P = 0.0124). The treatments can be applied to both the surveillance and the control, but ovitraps with biological larvicide Bti were more effective and safer considering the number of eggs laid and selectivity of pathogens for mosquitoes.

Isolation and molecular characterization of Bacillus thuringiensis found in soils of the Cerrado region of Brazil, and their toxicity to Aedes aegypti larvae

ABSTRACT This study investigated the potential of Bacillus thuringiensis isolates obtained in the Cerrado region of the Brazilian state of Maranhão for the biological control of Aedes aegypti larvae. The isolates were obtained from soil samples and the identification of the B. thuringiensis colonies was based on morphological characteristics. Bioassays were run to assess the pathogenicity and toxicity of the different strains of the B. thuringiensis against third-instar larvae of A. aegypti. Protein profiles were obtained by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Polymerase chain reaction assays were used to detect the toxin genes found in the bacterial isolates. Overall, 12 (4.0%) of the 300 isolates obtained from 45 soil samples were found to present larvicidal activity, with the BtMA-104, BtMA-401 and BtMA-560 isolates causing 100% of mortality. The BtMA-401 isolate was the most virulent, with the lowest median lethal concentration (LC50) (0.004 × 107 spores/mL), followed by the Bacillus thuringiensis var. israelensis standard (0.32 × 107 spores/mL). The protein profiles of BtMA-25 and BtMA-401 isolates indicated the presence of molecular mass consistent with the presence of the proteins Cry4Aa, Cry11Aa and Cyt1, similar to the profile of Bacillus thuringiensis var. israelensis IPS-82. Surprisingly, however, none of the cry and cyt genes analyzed were amplified in the isolate BtMA-401. The results of the present study revealed the larvicidal potential of B. thuringiensis isolates found in the soils of the Cerrado region from Maranhão, although further research will be necessary to better elucidate and describe other genes associated with the production of insecticidal toxins in these isolates.

Anopheles diversity and malaria infection in the cocais zone, state of Maranhão, Brazil

A survey of the Anopheles species was conducted in the municipality of São Mateus, in the state of Maranhão. Species hematophagy habits, the influence of seasonality as well as the vector's infection by Plasmodium were studied. The female Anopheles mosquitoes were captured between February and December 2010 and in March 2012, from 18h00 to 21h00, in intra and peridomiciles. PCR was used for the infection studies. A total 615 specimens of Anopheles were captured, of which 223 (36.2%) in the locality of Piquizeiro and 392 (63.8%) on the Retiro Velho Farm belonging to the species An. nuneztovari, An. darlingi, An. triannulatus, An. albitarsise, and An. oswaldoi. In Piquizeiro most specimens were captured in the intradomiciliary area, while on the Retiro Velho Farm they were mostly found in the peridomiciliary area. The results show the influence of seasonality and time of capture in the hematophagy frequency of the captured Anopheles. The negative result for Plasmodium infection demonstrates a reduction in the number of malaria cases in the State during the study period

Effect of Bacillus sphaericus Neide on Anopheles (Diptera: Culicidae) and associated insect fauna in fish ponds in the Amazon

ABSTRACTWe analyzed the effects of Bacillus sphaericus on Anopheles larvae and on the associated insect fauna in fish farming ponds. Five breeding sites in the peri-urban area of the city of Manaus, AM, Brazil, were studied. Seven samples were collected from each breeding site and B. sphaericus was applied and reapplied after 15 days. The samples were made at 24 h before application, 24 h post-application and 5 and 15 days post-application. We determined abundance, larval reduction and larval density for Anopheles, and abundance, richness, Shannon diversity index and classified according to the functional trophic groups for associated insect fauna. A total of 904 Anopheles larvae were collected and distributed into five species. Density data and larval reduction demonstrated the rapid effect of the biolarvicide 24 h after application. A total of 4874 associated aquatic insects belonging to six orders and 23 families were collected. Regression analysis of diversity and richness indicated that the application of the biolarvicide had no influence on these indices and thus no effect on the associated insect fauna for a period of 30 days. B. sphaericus was found to be highly effective against the larvae of Anopheles, eliminating the larvae in the first days after application, with no effect on the associated insect fauna present in the fish ponds analyzed.

Isolation of Bacillus thuringiensis from the state of Amazonas, in Brazil, and screening against Aedes aegypti (Diptera, Culicidae)

We investigated the use of Bacillus thuringiensis isolated in the state of Amazonas, in Brazil, for the biological control of the dengue vector Aedes aegypti. From 25 soil samples collected in nine municipalities, 484 bacterial colonies were obtained, 57 (11.78%) of which were identified as B. thuringiensis. Six isolates, IBt-03, IBt-06, IBt-07, IBt-28, IBt-30, and BtAM-27 showed insecticidal activity, and only BtAM-27 presents the five genes investigated cry4Aa, cry4Ba, cry10Aa, cry11Aa, and cry11Ba. The IBt-07 and IBt- 28, with lower LC50 values, showed equal toxicity compared to the standards. The isolates of B. thuringiensis from Amazonas constitute potential new means of biological control for A. aegypti, because of their larvicidal activity and the possibility that they may also contain new combinations of toxins.

Ecoepidemiology and biology of Eratyrus mucronatus Stål, 1859 (Hemiptera: Reduviidae: Triatominae), a sylvatic vector of Chagas disease in the Brazilian Amazon

Introduction Eratyrus mucronatus Stål, 1859 is a wild triatomine vector of Trypanosoma cruzi Chagas, 1909. However, little is known regarding the biology and ecoepidemiology of this triatomine in the Brazilian Amazon. The present study describes the biology of E. mucronatus grown under laboratory conditions and the epidemiological aspects of its natural breeding sites. Methods Five colonies were monitored in the field for 3 years. Temperature and humidity measurements were taken in the mornings and afternoons at the natural breeding sites, and the behavior and distribution of the nymphs and adults were observed in the wild colony. We also monitored the life cycle under controlled laboratory conditions. Results Some factors that were considered decisive for the establishment of these colonies were present at all of the colonies studied in the field. These factors included an active termite nest, a vertebrate for repast, and dry and shaded substrates with temperatures of 24-28°C and with humidity of 80-90%. A generation was developed in 274 days under these microclimatic conditions in the laboratory. Conclusions The climatic variables described in the field indicate that these environmental parameters have a limiting effect on the dispersal and colonization of E. mucronatus to new environments. ...

Larvicidal effects of endophytic and basidiomycete fungus extracts on Aedes and Anopheles larvae (Diptera, Culicidae)

Introduction In vitro bioassays were performed to access the larvicidal activity of crude extracts from the endophytic fungus Pestalotiopsis virgulata (Melanconiales, Amphisphaeriaceae) and the saprophytic fungus Pycnoporus sanguineus (Basidiomycetes, Polyporaceae) against the mosquitoes Aedes aegypti and Anopheles nuneztovari. Methods The extracts were tested at concentrations of 100, 200, 300, 400 and 500ppm. Ethyl acetate mycelia (EAM) extracts and liquid culture media (LCM) from Pe. virgulata and Py. sanguineus were tested against third instar larvae of Ae. aegypti and An. nuneztovari. Results The larvicidal activity of the EAM extracts from Pe. virgulata against Ae. aegypti had an LC50=101.8ppm, and the extract from the basidiomycete fungus Py. sanguineus had an LC50=156.8ppm against the Ae. aegypti larvae. The Pe. virgulata extract had an LC50=16.3ppm against the An. nuneztovari larvae, and the Py. sanguineus extract had an LC50=87.2ppm against these larvae. Conclusions These results highlight the larvicidal effect of EAM extracts from the endophyte Pe. virgulata against the two larval mosquitoes tested. Thus, Pe. virgulata and Py. sanguineus have the potential for the production of bioactive substances against larvae of these two tropical disease vectors, with An. nuneztovari being more susceptible to these extracts. .

Evaluation of larvicidal activity and brine shrimp toxicity of rhizome extracts of Zingiber zerumbet (L.) Smith

Introduction In this study, we used dichloromethane (DCM) and methanol (MeOH) extracts of the Zingiber zerumbet rhizome to evaluate brine shrimp lethality and larvicidal activity on Aedes aegypti and Anopheles nuneztovari mosquitoes. Methods Bioassays were performed by exposing third-instar larvae of each mosquito species to the DCM or MeOH extracts. Results Probit analysis with DCM and MeOH extracts demonstrated efficient larvicidal activity against A. aegypti and A. nuneztovari larvae. Conclusions The DCM and MeOH extracts showed higher activity against A. nuneztovari larvae than against A. aegypti larvae, suggesting that the extracts have species-specific activity. .

Variation in Aedes aegypti (Linnaeus) (Diptera, Culicidae) infestation in artificial containers in Caxias, state of Maranhão, Brazil / Variação da infestação de Aedes aegypti (Linnaeus), (Diptera, Culicidae) em recipientes artificiais em Caxias, estado do Maranhão, Brasil

INTRODUCTION: Dengue is a serious public health problem worldwide, with cases reported annually in tropical and subtropical regions. Aedes aegypti (Linnaeus, 1762), the main vector of dengue, is a domiciliary species with high dispersal and survival capacities and can use various artificial containers as breeding sites. We assessed potential container breeding sites of A. aegypti in the municipality of Caxias, Maranhão, Brazil. METHODS: In the initial phase, we analyzed 900 properties in 3 neighborhoods during the dry and rainy seasons (August-October 2005 and February-April 2006, respectively). During the second sampling period, September 2006-August 2007, we used 5 assessment cycles for 300 properties in a single neighborhood. RESULTS: During the dry and rainy seasons, water-storage containers comprised 55.7% (n = 1,970) and 48.5% (n = 1,836) of the total containers inspected, and showed the highest productivity of immature A. aegypti; we found 23.7 and 106.1 individuals/container, respectively, in peridomicile sites. In intradomicile sites, water-storage containers were also the most important breeding sites with 86.4% (n = 973) and 85.6% (n = 900) of all containers and a mean of 7.9 and 108.3 individuals/container in the dry and rainy seaso-October 2006 (1,342). The highest number of positives (70) was recorded in May, mostly (94%) in storage containers. CONCLUSIONS: Storage containers are the principal and most productive A. aegypti breeding sites and are a major contributing factor to the maintenance of this vector in Caxias.

INTRODUÇÃO: A dengue constitui de um sério problema de saúde pública mundial, com casos sendo registrados anualmente nas regiões tropicais e subtropicais. O Aedes aegypti(Linnaeus, 1762) é o principal vetor da doença, um mosquito domiciliado de fácil dispersão e sobrevivência, com capacidade de utilizar variados recipientes artificiais como criadouro. Em vista disso, neste trabalho investigou-se os tipos de recipientes potenciais criadouros de A. aegypti na Cidade de Caxias, Maranhão, Brasil. MÉTODOS: Inicialmente, a pesquisa foi desenvolvida em três bairros e 900 imóveis analisados no período da seca e das chuvas (agosto a outubro de 2005 e fevereiro a abril de 2006, respectivamente). Um segundo período de amostragem ocorreu de setembro de 2006 a agosto de 2007 em que inspeções de cinco ciclos foram desenvolvidas em um dos bairros com 300 imóveis amostrados. RESULTADOS: Os recipientes de armazenamento de água representaram 55,7% (n=1.970) e 48,5% (n=1.836) do total dos inspecionados, e maior produtividade de imaturos de A. aegypti, com proporção de 23,7 e 106,1 por recipiente no peridomicílio, nas estações seca e chuvosa respectivamente. No intradomicílio, também foi mais representativo, 86,4% (n=973) e 84,6% (n=900), apresentando média de 7,9 e 108,3 indivíduos, nas duas estações. O maior número de recipientes com água foi registrado em setembro e outubro 2006 (1.342), obtendo-se maior número de positivos (70) no mês de maio, sendo (94%) pertencentes ao grupo armazenamento. CONCLUSÕES: Armazenamento são os principais criadouros de A. aegypti, contribuindo na manutenção do vetor na cidade de Caxias, Maranhão.

Evaluation of students' knowledge as a contribution to dengue control programs / Avaliação do conhecimento dos estudantes como contribuição ao programa de controle da dengue

Trata-se de um inquérito amostral (700 entrevistas) realizado em 14 Escolas Públicas da Rede Municipal de Ensino na cidade de Caxias, Estado do Maranhão. O inquérito foi realizado entre julho e dezembro de 2007, em escolas localizadas em sete bairros periféricos da zona oeste, os quais apresentaram registros de alta densidade de imaturos de Aedes aegypti nos últimos três anos. Avaliou-se por meio da aplicação de questionário fechado, o conhecimento dos escolares sobre o dengue, seu vetor e prevenção. Os resultados mostraram que as escolas do bairro Trizidela, com melhores condições sociais e urbanas em relação aos demais bairros periféricos, apresentaram estudantes com conhecimentos mais adequados. Contudo, as campanhas educativas são necessárias como medidas para fortalecer as mudanças de comportamento da população, pois foi mencionada a existência de criadouros nas áreas examinadas, com maior prevalência dos recipientes de armazenamento no bairro Tamarineiro. A pesquisa pode servir como subsídio para orientar novas ações educativas das equipes locais de controle do dengue.

This study describes a survey (n=700) carried out in 14 elementary schools in the municipality of Caxias, State of Maranhão, Brazil. The survey was conducted between July and December 2007 in schools from seven neighborhoods on the outskirts of the western part of the municipality, where for the past three years high densities of immature Aedes aegypti mosquitoes have been recorded. The students' knowledge of dengue, its vector, and disease prevention was evaluated by targeted questionnaires. The students with the most comprehensive knowledge were found in schools in the Trizidela neighborhood, which has better social and urban conditions than the other neighborhoods. Moreover, educational campaigns are necessary to reinforce behavioral changes of the population, because the existence of breeding sites in the areas examined was mentioned, especially in the Tamarineiro neighborhood. The survey can be used to assist with new educational activities of local teams working with dengue control.

Variabilidade genética em populações de Anopheles darlingi (Diptera: Culicidae) e relação ao comportamento da atividade de picar, analisada por RAPD / Genetic variability in populations of Anopheles darlingi (Diptera: Culicidae) and relationship to biting activity behavior as analyzed by RAPD

Duas populações naturais de Anopheles darlingi foram analisadas quanto aos padrões de variabilidade genética relacionados ao comportamento hematofágico, cujas coletas foram realizadas no intra, peri e extradomicíio, em dois municípios do Estado do Amazonas: Coari e Manaus. Os resultados evidenciaram amplo número de fragmentos polimórficos, bem como elevada variabilidade genética nessas populações. Na população de Coari, a porcentagem de locos polimórficos (P) e heterozigosidade (He) variou de 77,63% - 84,86% e 0,2851 0,3069, respectivamente, sendo a maior variabilidade genética detectada nas subpopulações do intradomicílio, e a menor nas do peridomicílio. A população de Manaus mostrou variabilidade genética similar a de Coari (P= 75% - 78,94% e He= 0,2732 0,2741), onde também foi detectada maior variabilidade genética no intradomicílio. Os dados de qui-quadrado (x²= 695,89; GL= 304; P < 0,001) e de F ST (F ST= 0,0775 ± 0,0072) foram significativos, indicando uma estruturação micro geográfica, decorrente de alguma redução no fluxo gênico. Esses resultados podem ser interpretados como sendo em resposta à pressão de seleção face aos inseticidas, que permanecem residuais nas paredes dos domicílios.

Two natural populations of Anopheles darlingi, collected in the intra, peri and extra domicile of two townships in the State of Amazonas, Coari and Manaus, were assayed as to their hematophagic behaviour-related genetic variability patterns. Findings revealed a large number of polymorphic fragments as well as high genetic variability in these populations. Polymorphic loci rate (P) and heterozygosity (He) in the Coari population varied between 77.63% - 84.86% and 0.2851 0.3069, respectively, with the highest and lowest genetic variability being detected in the intra- and peri-domicile sub-populations, respectively. The Manaus population showed genetic variability and heterozygosity similar to those in Coari (P= 75% - 78.94% and He= 0.2732 0.2741), where higher genetic variability was detected in the intra-domicile as well. Chi-square data (x²= 695.89; GL= 304; P < 0.001) and F ST (F ST= 0.0775 ± 0.0072) were significant, indicating micro-geographic structuring resulting from some decreased gene flow. These findings point out the selective pressure response to the residual insecticide remaining on household walls after the entire neighbourhood had been sprayed with it during malaria control programs.

Genetic variability among Anopheles species belonging to the Nyssorhynchus and Anopheles subgenera in the Amazon region / Variabilidade genética entre espécies de Anopheles dos subgêneros Nyssorhynchus e Anopheles da região Amazônica

INTRODUCTION: Isoenzymatic analyses were performed involving species of the Nyssorhynchus and Anopheles subgenera in order to estimate the intra and interspecies genetic variability. METHODS: Mosquitoes were caught at different localities in the Amazon region. The collection and rearing of mosquitoes in the laboratory followed specific protocols. For the genetic variability analyses, the technique of horizontal electrophoresis on starch and starch-agarose gel with appropriate buffer systems was used. The alloenzyme variation was estimated using the Biosys-1 software. RESULTS: Out of the 13 loci, eight were polymorphic. Anopheles nuneztovari presented the largest number of alleles per locus, while the smallest number was detected in Anopheles marajoara from Macapá. The largest number of polymorphic loci was found for Anopheles marajoara from Maruanum and the smallest for Anopheles benarrochi (Guayará Mirim). Anopheles darlingi (Macapá) presented the greatest heterozygosity (Ho = 0.167 ± 0.071), while the lowest heterozygosity (Ho = 0.045 ± 0.019) was observed in Anopheles intermedius (Pacoval) of the subgenus Anopheles. Wright's F coefficient revealed considerable genetic structuring between the populations of Anopheles darlingi (Fst = 0.110) and between the populations of Anopheles marajoara (Fst = 0.082). CONCLUSIONS: Considering all the species studied, the genetic distance ranged from 0.008 to 1.114. The greatest distance was between Anopheles mattogrossensis and Anopheles oswaldoi, while the smallest was between the Anopheles benarrochi populations.

INTRODUÇÃO: Análises isoenzimáticas foram realizadas envolvendo espécies dos subgêneros Nyssorhynchus e Anopheles para estimar a variabilidade genética intra e interespecífica. MÉTODOS: Os mosquitos foram capturados em diferentes localidades da região Amazônica. A coleta e a criação dos mosquitos em laboratório foram conforme protocolos específicos. Na análise da variabilidade genética empregou-se a técnica de eletroforese horizontal em géis de amido e amido-agarose com sistemas tampões apropriados. A variação alozímica foi estimada pelo Programa Biosys-1. RESULTADOS: Dos 13 loci, oito foram polimórficos. Anopheles nuneztovari apresentou o maior número de alelos por loco, sendo o menor detectado para Anopheles albitarsis (Macapá). O maior número de loci polimórficos foi detectado em Anopheles marajoara (Maruanum) e o menor, em Anopheles benarrochi (Guayará Mirim). Anopheles darlingi (Macapá) apresentou a maior heterozigosidade (Ho = 0,167 ± 0.071) e a menor (Ho = 0,045 ± 0.019) foi observada em Anopheles intermedius (Pacoval) do subgênero Anopheles. O coeficiente F de Wright evidenciou considerável estruturação genética entre populações de Anopheles darlingi (Fst= 0,110) e entre as populações de Anopheles marajoara (Fst= 0,082). CONCLUSÕES: Considerando todas as espécies estudadas, a distância genética variou de 0,008 a 1,144, onde a maior distância foi entre Anopheles mattogrossensis e Anopheles oswaldoi e a menor, entre as populações de Anopheles benarrochi.

Gram-scale isolation of isobrucein B and neosergeolide from Picrolemma sprucei Hook. f. / Isolamento de isobruceina B e neosergeolida de Picrolemma sprucei Hook. f. em escala-grama

Quassinoids neosergeolide and isobrucein B, obtained from Picrolemma sprucei, have proven in vitro antitumor, antimalarial, anthelminthic, cytotoxic, insecticide and leishmanicidal activities. There is interest in the in vivo pharmacological study of these natural compounds and their semi-synthetic derivatives, however, the quantities obtained in previous extraction processes have been shown to be a limiting factor for continuation of these studies. Herein, we describe a method for obtaining grams of these quassinoids whose purification relies only on recrystallization.

Os quassinóides neosergeolida e isobruceína B, obtidos de Picrolemma sprucei, possuem atividades antitumoral, antimalárica, anti-helmíntica, citotóxica, inseticida e anti-leishmania comprovadas em estudos in vitro. Há interesse no estudo farmacológico in vivo dessas substâncias naturais e de seus derivados semi-sintéticos, porém a quantidade obtida nos processos de extração tem se mostrado um fator limitante à continuação desses estudos. No presente trabalho, descrevemos um método para obtenção de gramas desses quassinóides cuja purificação depende apenas de cristalização fracionada.

Controle da malária: eficácia de formulados de Bacillus sphaericus 2362 contra larvas de espécies de anopheles em criadouros artificiais - tanques de psicultura e criadouros de Olaria / Malaria control: efficacy of Bacillus sphaericus 2362 formulations against anopheles species larvae in man-made breeding sites such as fish culture ponds and brickyard puddles

Objetivo: Avaliar a eficácia e a persistência de diferentes formulações de Bacillus sphaericus 2362, em doses com o dobro do que é recomendado pels fabricantes, para controle das formas imaturas de espécies de Anopheles, vetor da malária, diante da composição da água dos criadouros artificiais. Métodos: Tanques de psicultura e lagos de olaria, localizados nos municípios de Manaus e Iranduba e contendo formas imaturas de anofelinos, foram tratados com concentrações dobradas. As doses dos larvicidas - Vectolex - 22Kg/ha, Griselesf- 200L/ha e Spherimos- 6L/ha - foram aplicadas nos seguintes criadouros: Sítio Fazendinha- 7 tanques e 1 controle (sem larvicidas); Sítio Três Irmãos- 6 tanques e 1 controle; Sítio Santa Cecília- 9 tanques e 2 controles: Olaria Cerama- 26 lagoas e 5 controles. Coletas de anofelinos para determinar os índices de larva por homem/hora (ILHH) das formas jovens (primeiro e segundo estádios) e das formas maduras (terceiro e quarto estádios) foram feitas antes da aplicação e após no segundo, sétimo, décimo quarto, vigésimo primeiro, vigésimo oitavo e trigésimo quinto dias. Resultados: Os resultados da densidade larvária nos criadouros artificiais demonstram que, nos tanques de psicultura, o número de larvas observado foi quatro vezes maior (33.729 larvas) do que nos criadouros de olaria (7.972 larvas). Na avaliação dos formulados nos tanques de psicultura de Manaus e Iranduba, observaram-se menores valores do ILHH, na leitura do segundo dia, nos criadouros onde se aplicam Vectolex e Spherimos do que nos criadouros-controle; nos tanques tratados com Griselesf, ao contrário, os valores do ILHH estavam próximos aos encontrados no controle, ultrapassando esses índices larvários nas demais observações. Os formulados Spherimos e Vectolex apresentaram padrões similares de redução próximos a 100por cento, no segundo dia de observação, tanto para as larvas jovens como para as maduras. Quando se consideram os resultados para o Griselesf...

Analysis of toxicity on Bacillus sphaericus from amazonian soils to Anopheles darlingi and Culex quinquefasciatus larvae / Análise da toxicidade em Bacillus sphaericus de solos da Amazônia em larvas de Anopheles darlingi e Culex quinquefasciatus

Bioassays under laboratory conditions aiming to determine the larvicidal activity of Bacillus sphaericus were carried out on Anopheles darlingi and Culex quinquefasciatus. In order to estimate the toxicity through median lethal concentration (LC50) and the relative potency of the strains to B. sphaericus standard strain 2362, probit analysis was performed utilizing the POLO-PC program. The findings of LC50 pointed out high effectiveness on strains IB15 (0.040 ppm), IB19 and S1116 (0.048 ppm), IB16 (0.052 ppm) and S265 (0.057 ppm). Strain IB15 presented nearly 50 percent more potency than strain 2362 in bioassays conducted on A. darlingi. It was observed that IB16 and S1116 strains were the most powerful against C. quinquefasciatus, showing to be about 300-400 percent stronger than 2362 strain. The results show that laboratory conditioned evaluation can be an important way to select promising bacteria with entomopathogenic action on biolarvicides production for use on mosquitoes breeding sites.

Bioensaios sob condições de laboratório foram realizados em larvas de Anopheles darlingi e Culex quinquefasciatus, visando determinar a atividade larvicida de Bacillus sphaericus. Para estimar a toxicidade através da concentração letal mediana (CL50) e a potência das estirpes em relação à estirpe padrão 2362, foi realizada a análise de probit utilizando o programa POLO-PC. Os resultados da CL50 apontaram alta efetividade para as estirpes IB15 (0,040 ppm), IB19 e S1116 (0,048 ppm), IB16 (0,052 ppm) e S265 (0,057 ppm). A estirpe IB15 apresentou potência cerca de 50 por cento maior que a estirpe 2362 nos bioensaios realizados com A. darlingi. Foi observado que as estirpes IB16 e S1116 foram as mais tóxicas para controle de C. quinquefasciatus, mostrando-se cerca de 300-400 por cento mais potente. Os resultados mostram que a avaliação em laboratório é uma importante etapa para selecionar bactérias com ação entomopatogênica a serem usadas na para a produção de biolarvicidas para uso nos criadouros das larvas de mosquitos.