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      Influência dos fatores abióticos na efetividade de Bacillus thuringiensis var. israelensis (Berliner, 1911) para larvas de Aedes aegypti (Linnaeus, 1762) Translated title: Influencia de los factores abióticos en la efectividad de la Bacillus thuringiensis israelensis (Berliner, 1911) contra larvas de Aedes aegypti (Linnaeus, 1762) Translated title: Influence of abiotic factors on the effectiveness of Bacillus thuringiensis israelensis (Berliner, 1911) against larvae of Aedes aegypti (Linnaeus, 1762)

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          Abstract

          Introdução: Bacillus thuringiensis, tem sido usado mundialmente para o controle de culicídeos, especialmente no combate ao Aedes aegypti. Várias formulações vêm sendo fabricadas, no entanto, a efetividade desses inseticidas variam bastante de acordo com as condições ambientais. Objetivo: avaliar a influência dos fatores abióticos na efetividade de B. thuringiensis var. israelensis para larvas de Ae. Aegypti. Métodos: realizou-se bioensaio experimental no campus do CESC/UEMA, com utilização de 20 tanques de cimento, destes, 10 ficaram expostos aos fatores ambientais, e apenas 5 foram tratados e 5 serviram como controle. Os outros 10 tanques foram colocados à sombra, também 5 tratados e 5 não tratados (controle). Após o tratamento foram colocadas 25 larvas em estádio L 3 em cada tanque e realizadas leituras de mortalidade após 24 horas e a cada 7 dias. Semanalmente foram coletadas amostras de água de todos os tanques para medir o número de esporos viáveis e avaliar a reciclagem bacteriana. Resultados e Discussão: o larvicida apresentou eficácia inicial, matando 100 % das larvas nos tanques que estavam ao sol e a sombra. Os fatores ambientais, insolação, temperatura e pluviometria afetaram negativamente a efetividade do produto, pois se observou diminuição na eficácia do produto ao longo da realização do experimento. Observou-se variação do número de esporos ao longo do desenvolvimento do experimento, demonstrando que a bactéria apresenta potencial de reciclagem. Conclusão: esses dados servem como parâmetros para melhoramento de inseticidas à base de Bti, no sentido de se fabricar formulações mais adequadas às condições ambientais da nossa região.

          Translated abstract

          Introducción: la Bacillus thuringiensis se ha utilizado en muchas regiones del mundo para el control de los mosquitos, sobre todo en el combate contra el Aedes aegypti. Se han elaborado varias formulaciones; sin embargo, la efectividad de esos insecticidas varía considerablemente según las condiciones ambientales. Objetivo: evaluar la influencia de los factores abióticos en la efectividad de la B. thuringiensis var. israelensis contra larvas de Ae. aegypti. Métodos: se realizaron bioensayos experimentales en el campus de la CESC / UEMA. Se utilizaron 20 tanques de cemento, 10 de los cuales quedaron expuestos a factores ambientales. De ellos, 5 fueron tratados y 5 sirvieron como controles. Los otros 10 tanques fueron ubicados en la sombra, y también en este caso 5 fueron tratados y 5 no (controles). Después del tratamiento, se colocaron 25 larvas en estadio larval L3 en cada tanque. Se realizaron lecturas de mortalidad luego de 24 horas y cada 7 días. Se tomaron muestras de agua de todos los tanques una vez a la semana para comprobar el número de esporas viables y evaluar el reciclaje bacteriano. Resultados y discusión: el larvicida mostró eficacia inicial, matando el 100 % de las larvas de tanques ubicados tanto al sol como en la sombra. Los factores ambientales, la luz solar, la temperatura y la lluvia afectaron negativamente la efectividad del producto, constatándose una reducción de la misma a lo largo del experimento. Se observaron variaciones en el número de esporas durante el experimento, lo que demuestra que la bacteria presenta potencial de reciclaje. Conclusión: los datos obtenidos sirven de parámetros para el mejoramiento de los insecticidas a base de Bti, con vistas a elaborar formulaciones más acordes con las condiciones ambientales de nuestra región.

          Translated abstract

          Introduction: Bacillus thuringiensis , has been used worldwide for the control of mosquitoes, particularly in combating Aedes aegypti. Various formulations have been made however, the effectiveness of these insecticides vary varies considerably according to the environmental conditions. Objective: to evaluate the influence of abiotic factors on the effectiveness of B. thuringiensis var. israelensis to against larvae of Ae. aegypti. Methods: we conducted bioassay experiments in the campus of the CESC / UEMA. With use of 20 Twenty cement tanks, of these, were used, 10 of which were exposed to environmental factors, and only. Of these, 5 were treated and 5 served as controls. The other 10 tanks were placed in the shade, also again 5 were treated and 5 untreated were not (control). After treatment, the 25 stage L 3 larvae were placed in 25 L 3 each stage tank and mortality. Mortality readings were taken after 24 hours and every 7 days. Weekly water samples were collected from all tanks to measure once a week to check the number of viable spores and evaluate bacterial recycling. Results and discussion: the larvicidal efficacy: The larvicide showed initial efficacy, killing 100 % of the larvae in tanks that were located both in the sun and in the shade. Environmental factors, sunlight, temperature and rainfall negatively affected the effectiveness of the product, because for there was a reduction in the effectiveness of the product throughout the experiment. It was observed variation in the number of spores during the development of the experiment demonstrating, showing that the bacterium has potential recyclability. Conclusion: these data serve as parameters for improving to in Bti-based insecticides, in order to make the with a view to making formulations more suited toin keeping with the environmental conditions of our region.

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          Climate variability and change in the United States: potential impacts on vector- and rodent-borne diseases.

          Diseases such as plague, typhus, malaria, yellow fever, and dengue fever, transmitted between humans by blood-feeding arthropods, were once common in the United States. Many of these diseases are no longer present, mainly because of changes in land use, agricultural methods, residential patterns, human behavior, and vector control. However, diseases that may be transmitted to humans from wild birds or mammals (zoonoses) continue to circulate in nature in many parts of the country. Most vector-borne diseases exhibit a distinct seasonal pattern, which clearly suggests that they are weather sensitive. Rainfall, temperature, and other weather variables affect in many ways both the vectors and the pathogens they transmit. For example, high temperatures can increase or reduce survival rate, depending on the vector, its behavior, ecology, and many other factors. Thus, the probability of transmission may or may not be increased by higher temperatures. The tremendous growth in international travel increases the risk of importation of vector-borne diseases, some of which can be transmitted locally under suitable circumstances at the right time of the year. But demographic and sociologic factors also play a critical role in determining disease incidence, and it is unlikely that these diseases will cause major epidemics in the United States if the public health infrastructure is maintained and improved.
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            Aspectos críticos do controle do dengue no Brasil

            O dengue é hoje a principal doença re-emergente no mundo. Na ausência de uma vacina preventiva eficaz, de tratamento etiológico e quimioprofilaxia efetivos, o único elo vulnerável para reduzir a sua transmissão é o mosquito Aedes aegypti, seu principal vetor. As dificuldades de combater este mosquito, em grandes e médias cidades, são muitas. Há facilidades para sua proliferação e limitações para reduzir seus índices de infestação, geradas pela complexidade da vida urbana atual. Os objetivos do controle do dengue devem ser estabelecidos com base nos conhecimentos científicos e técnicos disponíveis. Assim, não sendo possível evitar casos de dengue em áreas infestadas pelo A. aegypti, é possível prevenir epidemias de grandes dimensões por meio do aprimoramento da vigilância epidemiológica, e é possível e factível reduzir a letalidade da doença, dos níveis atuais de 5 a 6% para cerca de 1% das formas graves. A elaboração e execução de planos estratégicos de organização da assistência aos casos suspeitos de dengue têm mostrado, tanto em outros países, como em algumas cidades brasileiras, ser um instrumento muito útil na redução da letalidade.
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              Effect of Insecticide Resistance on Development, Longevity and Reproduction of Field or Laboratory Selected Aedes aegypti Populations

              Aedes aegypti dispersion is the major reason for the increase in dengue transmission in South America. In Brazil, control of this mosquito strongly relies on the use of pyrethroids and organophosphates against adults and larvae, respectively. In consequence, many Ae. aegypti field populations are resistant to these compounds. Resistance has a significant adaptive value in the presence of insecticide treatment. However some selected mechanisms can influence important biological processes, leading to a high fitness cost in the absence of insecticide pressure. We investigated the dynamics of insecticide resistance and its potential fitness cost in five field populations and in a lineage selected for deltamethrin resistance in the laboratory, for nine generations. For all populations the life-trait parameters investigated were larval development, sex ratio, adult longevity, relative amount of ingested blood, rate of ovipositing females, size of egglaying and eggs viability. In the five natural populations, the effects on the life-trait parameters were discrete but directly proportional to resistance level. In addition, several viability parameters were strongly affected in the laboratory selected population compared to its unselected control. Our results suggest that mechanisms selected for organophosphate and pyrethroid resistance caused the accumulation of alleles with negative effects on different life-traits and corroborate the hypothesis that insecticide resistance is associated with a high fitness cost.
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                Author and article information

                Journal
                mtr
                Revista Cubana de Medicina Tropical
                Rev Cubana Med Trop
                Centro Nacional de Información de Ciencias Médicas (Ciudad de la Habana, , Cuba )
                0375-0760
                1561-3054
                August 2014
                : 66
                : 2
                : 174-190
                Affiliations
                [03] Manaus AM orgnameInstituto Nacional de Pesquisas da Amazônia orgdiv1Laboratório de Malária e Dengue Brasil
                [01] orgnameUniversidade Estadual do Maranhao orgdiv1Laboratório de Entomologia Médica Brasil
                [02] Campus Codó MA orgnameUniversidade Federal do Maranhao Brasil
                Article
                S0375-07602014000200003 S0375-0760(14)06600203
                e4e7c648-00c5-4eae-b708-de93997ce407

                This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

                History
                : 28 February 2014
                : 07 May 2013
                Page count
                Figures: 0, Tables: 0, Equations: 0, References: 28, Pages: 17
                Product

                SciELO Cuba

                Categories
                ARTÍCULOS ORIGINALES

                dengue,controle biológico,Bacillus thuringiensis,control biológico,vector,biological control,vetor

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