Acción insecticida de análogos sintéticos de girgensohnina y de aceites esenciales sobre Rhodnius prolixus (Hemiptera: Reduviidae)

Introduction: The alkaloid girgensohnine has been used as a natural model in the synthesis of new alkaloid-like alpha-aminonitriles with insecticidal effect against disease vectors.Objective: To evaluate the biocide activity of girgensohnine analogues and essential oils of Cymbopogon flexuosus, Citrus sinensis and Eucalyptus citriodora in stage I and stage V Rhodnius prolixus nymphs.Materials and methods: We used a topical application model in tergites and sternites, as well as exposure to treated surfaces with different exploratory doses of each of the molecules and essential oils to determine the lethal doses (LD50 and LD95).Results: Analogue 3 showed the highest insecticidal activity with 83.3±16.7% of mortality when applied on tergites, 38.9±4.8% on sternites and 16.7±0% on treated surfaces in stage I nymphs at 72 hours (h) and 500 mg.L-1. In stage V nymphs, the compounds induced mortality only in sternums (11.1±9.6% for analogue 6 and 5.5±4.7% for analogues 3 and 7 at 72 h and 1500 mg.L-1). The lethal doses for molecule 3 on tergites in stage I nymphs were LD50 225.60 mg.L-1 and LD95 955.90 mg.L-1. The insecticidal effect of essential oils was observed only in stage I nymphs, with 11.1±4.8% for C. flexuosus when applied in sternites, while using exposure to surfaces treated it was 5.6±4.8% for C. sinensis applied on tergites and 8.3±0% on sternites at 72 h and 1000 mg.L-1.Conclusion: Synthetic girgensohnine analogues, and C. flexuosus and C. sinensis essential oils showed insecticidal activity in R. prolixus. Analogue 3 showed the greatest insecticidal activity among all molecules and oils evaluated under our laboratory conditions.Introducción. El alcaloide natural girgensohnina se ha usado como modelo en la síntesis de nuevos análogos de alcaloidales alfa-aminonitrílicos con efecto insecticida en vectores de enfermedades.Objetivo. Evaluar la actividad biocida de análogos de girgensohnina y de aceites esenciales de las plantas Cymbopogon flexuosus, Citrus sinensis y Eucalyptus citriodora en ninfas de estadios I y V de Rhodnius prolixus.Materiales y métodos. Se empleó la aplicación tópica en terguitos, esternitos y superficies tratadas con diferentes dosis exploratorias de cada una de las moléculas y aceites esenciales para determinar las dosis letales (LD50 y LD95).Resultados. El análogo 3 tuvo la mayor actividad insecticida, con una mortalidad de 83,3±16,7% en los terguitos, de 38,9±4,8 % en los esternitos y de 16,7±0 % a las 72 horas en ninfas de estadio I expuestas a superficies tratadas y 500 mg.L-1. En las ninfas de estadio V solo se presentó mortalidad en los esternitos (11,1±9,6 % con el análogo 6 y 5,5±4,7 % con los análogos 3 y 7 a las 72 h y 1.500 mg.L-1). Las dosis letales para la molécula 3 en los terguitos de ninfas de estadio I fueron las siguientes: DL50, 225,60 mg.L-1y DL95, 955,90 mg.L-1. En cuanto a los aceites esenciales, el efecto insecticida solo se presentó con C. flexuosus (11,1±4,8%) en los esternitos de ninfas de estadio I expuestas a superficies tratadas; con C. sinensis (5,6±4,8%) en los terguitos y en los esternitos (8,3±0%) a las 72 horas y 1.000 mg.L-1.Conclusión. Los análogos sintéticos del alcaloide girgensohnina y los aceites esenciales de C. flexuosus y C. sinensis exhibieron actividad insecticida en R. prolixus. El análogo 3 exhibió la mayor actividad insecticida de todas las moléculas evaluadas bajo las condiciones de laboratorio

Dengue no Estado do Paraná, Brasil: distribuição temporal e espacial no período 1995-2007.

RESUMO   Objetivo: Analisar a distribuição espacial e temporal da dengue no Estado do Paraná e sua relação com o incremento de número de casos das áreas de fronteira entre 1995 e 2007. Métodos: Dados de ocorrência dos casos de dengue autóctones e importados em cada município paranaense foram georreferenciados com ArcView GIS 3.2. Foi realizada também uma análise de correlação de Pearson (r), relacionando o número de casos do Estado de Paraná com os Estados do Mato Grosso e São Paulo, Brasil, Argentina e Paraguai. Resultados: A análise dos mapas permitiu reconhecer áreas com maior incidência da virose e a direção da dispersão no Estado. É notável a ocorrência de três ondas epidêmicas, com picos nos biênios 1995/96, 2002/03 e 2006/07. Destacam-se as Regiões Metropolitanas de Londrina e Maringá e a cidade de Foz do Iguaçu, como grandes centros urbanos e com elevado número de casos da dengue. A área formada pelas mesorregiões Oeste, Centro-Oeste, Noroeste, Norte-Central e Norte Pioneiro contribuíram com 98,47% do total de casos, sendo 99,98% autóctones. Conclusões: A ocorrência de ondas epidêmicas e a contínua notificação de casos de dengue, com confirmação sorológica, é um indício de que este agravo se tornou endêmico no Estado. É observado que o maior número de casos no Estado do Paraná ocorre nas áreas de fronteira com o Paraguai e divisa com o Estado do Mato Grosso do Sul. Salud UIS 2010; 42: 113-122 Descritores: Epidemiologia, dengue, distribuição espacial, Aedes aegypti.   RESUMEN   Objetivo: Analizar la distribución espacial y temporal del dengue en el Estado de Paraná y su relación con el incremento de los casos en las áreas de frontera 1995-2007. Métodos: Datos de la ocurrencia de los casos autóctonos e importados en cada municipio paranaense fueron geo-referenciados con ArcVier GIS 3.2 fue también realizado un análisis de correlación de Pearson (r), relacionando el número de casos del Estado de Paraná con los Estados de Mato Grosso y São Paulo, Brasil, Argentina y Paraguay. Resultados: El análisis de los mapas permitió reconocer áreas con mayor incidencia de virus y la dirección de la dispersión en el Estado. Se notaron tres olas epidémicas, con picos en los bienios 1995/96, 2002/03 y 2006/07. Se destacan las regiones metropolitanas de Londrina y Maringá y la ciudad de Foz do Iguaçu, como grandes centros urbanos y con elevado número de casos del dengue. Las áreas formadas por las mesoregiones Oeste, Centro-Oeste, Noroeste, Norte-Central y Norte Pionero contribuyeron con 98,47% del total de casos, siendo 99,98% autóctonos. Conclusiones: La ocurrencia de olas epidémicas y la continua notificación de casos de dengue, con confirmación serológica, es un indicio de que este problema se ha transformado en endémico en el Estado. Es observado que el mayor número de casos en el estado de Paraná ocurre en las fronteras con Paraguay y límites con el Estado de Mato Grosso do Sul. Salud UIS 2010; 42: 113-122 Palabras clave: Epidemiología, dengue, distribución espacial, Aedes aegypti  ABSTRACT   Objective: To analyze the spatial and temporal distribution of dengue in the Paraná state and its relationship to the rising of number of cases in the border areas from 1995 to 2007. Methods: Data of occurrence of autochthonous and allochthonous dengue cases in Paraná were georeferenced whit ArcView GIS 3.2. It was also performed an analysis of the Pearson correlation (r) between the total number cases to State of Paraná with Mato Grosso and São Paulo states, Brazil, Argentina and Paraguay. Results: The maps’ analysis allowed the recognition of areas with higher dengue incidence and the direction of dispersion within the State. It is outstanding the occurrence of three epidemical waves with peaks in 1995/96, 2002/03 and 2006/07. It highlights the metropolitan regions of Londrina and Maringá and the city of Foz do Iguaçu, as large urban centers, present a high number of dengue cases. The area that comprises the West, Mid-west, Northwest, Mid-north and the so-called “Pioneer North” mesoregions contributed with 98.47% of the total number of cases and with 99.98% of solely the autochthonous ones. Conclusions: The occurrence of epidemic waves and the notification of continuous cases of dengue, with serologic confirmation, it is an indication that this disease has become endemic in the state. It is observed that the largest number of cases in the Parana state occurs in the border areas with Paraguay and currency with the Mato Grosso do Sul state. Salud UIS 2010; 42: 113-122 Keywords: Epidemiology, dengue, spatial distribution, Aedes aegypt

Dengue no Estado do Paraná, Brasil: distribuição temporal e espacial no período 1995-2007.

RESUMO   Objetivo: Analisar a distribuição espacial e temporal da dengue no Estado do Paraná e sua relação com o incremento de número de casos das áreas de fronteira entre 1995 e 2007. Métodos: Dados de ocorrência dos casos de dengue autóctones e importados em cada município paranaense foram georreferenciados com ArcView GIS 3.2. Foi realizada também uma análise de correlação de Pearson (r), relacionando o número de casos do Estado de Paraná com os Estados do Mato Grosso e São Paulo, Brasil, Argentina e Paraguai. Resultados: A análise dos mapas permitiu reconhecer áreas com maior incidência da virose e a direção da dispersão no Estado. É notável a ocorrência de três ondas epidêmicas, com picos nos biênios 1995/96, 2002/03 e 2006/07. Destacam-se as Regiões Metropolitanas de Londrina e Maringá e a cidade de Foz do Iguaçu, como grandes centros urbanos e com elevado número de casos da dengue. A área formada pelas mesorregiões Oeste, Centro-Oeste, Noroeste, Norte-Central e Norte Pioneiro contribuíram com 98,47% do total de casos, sendo 99,98% autóctones. Conclusões: A ocorrência de ondas epidêmicas e a contínua notificação de casos de dengue, com confirmação sorológica, é um indício de que este agravo se tornou endêmico no Estado. É observado que o maior número de casos no Estado do Paraná ocorre nas áreas de fronteira com o Paraguai e divisa com o Estado do Mato Grosso do Sul. Salud UIS 2010; 42: 113-122 Descritores: Epidemiologia, dengue, distribuição espacial, Aedes aegypti.   RESUMEN   Objetivo: Analizar la distribución espacial y temporal del dengue en el Estado de Paraná y su relación con el incremento de los casos en las áreas de frontera 1995-2007. Métodos: Datos de la ocurrencia de los casos autóctonos e importados en cada municipio paranaense fueron geo-referenciados con ArcVier GIS 3.2 fue también realizado un análisis de correlación de Pearson (r), relacionando el número de casos del Estado de Paraná con los Estados de Mato Grosso y São Paulo, Brasil, Argentina y Paraguay. Resultados: El análisis de los mapas permitió reconocer áreas con mayor incidencia de virus y la dirección de la dispersión en el Estado. Se notaron tres olas epidémicas, con picos en los bienios 1995/96, 2002/03 y 2006/07. Se destacan las regiones metropolitanas de Londrina y Maringá y la ciudad de Foz do Iguaçu, como grandes centros urbanos y con elevado número de casos del dengue. Las áreas formadas por las mesoregiones Oeste, Centro-Oeste, Noroeste, Norte-Central y Norte Pionero contribuyeron con 98,47% del total de casos, siendo 99,98% autóctonos. Conclusiones: La ocurrencia de olas epidémicas y la continua notificación de casos de dengue, con confirmación serológica, es un indicio de que este problema se ha transformado en endémico en el Estado. Es observado que el mayor número de casos en el estado de Paraná ocurre en las fronteras con Paraguay y límites con el Estado de Mato Grosso do Sul. Salud UIS 2010; 42: 113-122 Palabras clave: Epidemiología, dengue, distribución espacial, Aedes aegypti  ABSTRACT   Objective: To analyze the spatial and temporal distribution of dengue in the Paraná state and its relationship to the rising of number of cases in the border areas from 1995 to 2007. Methods: Data of occurrence of autochthonous and allochthonous dengue cases in Paraná were georeferenced whit ArcView GIS 3.2. It was also performed an analysis of the Pearson correlation (r) between the total number cases to State of Paraná with Mato Grosso and São Paulo states, Brazil, Argentina and Paraguay. Results: The maps’ analysis allowed the recognition of areas with higher dengue incidence and the direction of dispersion within the State. It is outstanding the occurrence of three epidemical waves with peaks in 1995/96, 2002/03 and 2006/07. It highlights the metropolitan regions of Londrina and Maringá and the city of Foz do Iguaçu, as large urban centers, present a high number of dengue cases. The area that comprises the West, Mid-west, Northwest, Mid-north and the so-called “Pioneer North” mesoregions contributed with 98.47% of the total number of cases and with 99.98% of solely the autochthonous ones. Conclusions: The occurrence of epidemic waves and the notification of continuous cases of dengue, with serologic confirmation, it is an indication that this disease has become endemic in the state. It is observed that the largest number of cases in the Parana state occurs in the border areas with Paraguay and currency with the Mato Grosso do Sul state. Salud UIS 2010; 42: 113-122 Keywords: Epidemiology, dengue, spatial distribution, Aedes aegypt

Dynamics of the control of Aedes (Stegomyia) aegypti Linnaeus (Diptera, Culicidae) by Bacillus thuringiensis var israelensis, related with temperature, density and concentration of insecticide

The dynamics of the control of Aedes (Stegomyia) aegypti Linnaeus, (Diptera, Culicidae) by Bacillus thuringiensis var israelensis has been related with the temperature, density and concentration of the insecticide. A mathematical model for biological control of Aedes aegypti with Bacillus thuringiensis var israelensis (Bti) was constructed by using data from the literature regarding the biology of the vector. The life cycle was described by differential equations. Lethal concentrations (LC50 and LC95) of Bti were determined in the laboratory under different experimental conditions. Temperature, colony, larvae density and bioinsecticide concentration presented marked differences in the analysis of the whole set of variables; although when analyzed individually, only the temperature and concentration showed changes. The simulations indicated an inverse relationship between temperature and mosquito population, nonetheless, faster growth of populations is reached at higher temperatures. As conclusion, the model suggests the use of integrated control strategies for immature and adult mosquitoes in order to achieve a reduction of Aedes aegypti

Insecticidal action of synthetic girgensohnine analogues and essential oils on Rhodnius prolixus (Hemiptera: Reduviidae)

Introduction: The alkaloid girgensohnine has been used as a natural model in the synthesis of new alkaloid-like alpha-aminonitriles with insecticidal effect against disease vectors. Objective: To evaluate the biocide activity of girgensohnine analogues and essential oils of Cymbopogon flexuosus, Citrus sinensis and Eucalyptus citriodora in stage I and stage V Rhodnius prolixus nymphs. Materials and methods: We used a topical application model in tergites and sternites, as well as exposure to treated surfaces with different exploratory doses of each of the molecules and essential oils to determine the lethal doses (LD50 and LD95). Results: Analogue 3 showed the highest insecticidal activity with 83.3±16.7% of mortality when applied on tergites, 38.9±4.8% on sternites and 16.7±0% on treated surfaces in stage I nymphs at 72 hours (h) and 500 mg.L-1. In stage V nymphs, the compounds induced mortality only in sternums (11.1±9.6% for analogue 6 and 5.5±4.7% for analogues 3 and 7 at 72 h and 1500 mg.L-1). The lethal doses for molecule 3 on tergites in stage I nymphs were LD50 225.60 mg.L-1 and LD95 955.90 mg.L-1. The insecticidal effect of essential oils was observed only in stage I nymphs, with 11.1±4.8% for C. flexuosus when applied in sternites, while using exposure to surfaces treated it was 5.6±4.8% for C. sinensis applied on tergites and 8.3±0% on sternites at 72 h and 1000 mg.L-1. Conclusion: Synthetic girgensohnine analogues, and C. flexuosus and C. sinensis essential oils showed insecticidal activity in R. prolixus. Analogue 3 showed the greatest insecticidal activity among all molecules and oils evaluated under our laboratory conditions

Synthesis of new α-amino nitriles with insecticidal action on Aedes aegypti (Diptera: Culicidae)

Aedes aegypti is the principal vector of arboviral pathogens that may cause diseases as dengue fever, chikungunya and zika. The harmful environmental effects of commercial pesticides coalesced with the development of insecticide-resistant populations encourage the discovery and generation of new alternative products as a tool to reduce the incidence of vector-borne diseases. In this work, through the classic three component Strecker reaction of commercial benzaldehydes, cyclic secondary amines and KCN, a new series of nine α-amino nitriles, girgensohnine analogs, has been synthetized and screened for larvicide and adulticide properties against A. aegypti, one of the dominant vectors of dengue, chikungunya and zika in tropical and subtropical areas all over the world. Molecules 3 and 4 were identified as potential larvicidal agents with LC50 values of 50.55 and 69.59 ppm, respectively. Molecule 3 showed 100% of mortality after 2 h of treatment when a concentration of 30 ppm in adulticidal assays was evaluated. Additionally, in order to elucidate the mode of action of these molecules, their acetylcholinesterase (AChE) inhibitory properties were evaluated using the Ellman assay. It was found that the molecules possess a weak AChE inhibitory activity with IC50 values between 148.80 and 259.40 μM, indicating that AChE could not be a principal target for insecticide activity. Keywords: Arthropod-borne diseases, Girgensohnine analogs, Strecker reaction, Insecticidal activity, Vector contro

Review of semiochemicals that mediate the oviposition of mosquitoes: a possible sustainable tool for the control and monitoring of Culicidae

The choice for suitable places for female mosquitoes to lay eggs is a key-factor for the survival of immature stages (eggs and larvae). This knowledge stands out in importance concerning the control of disease vectors. The selection of a place for oviposition requires a set of chemical, visual, olfactory and tactile cues that interact with the female before laying eggs, helping the localization of adequate sites for oviposition. The present paper presents a bibliographic revision on the main aspects of semiochemicals in regard to mosquitoes' oviposition, aiding the comprehension of their mechanisms and estimation of their potential as a tool for the monitoring and control of the Culicidae.A seleção de locais adequados pelas fêmeas de mosquitos para depositarem seus ovos é um fator chave para a sobrevivência de seus imaturos (ovos e larvas). O conhecimento das relações ecológicas implicadas neste processo é de grande importância quando se refere a vetores de agentes patogênicos. A determinação do local de oviposição pelas fêmeas grávidas envolve uma rede de mensagens químicas, visuais, olfativas e táteis que facilitam a localização de lugares adequados para depositarem seus ovos. Neste trabalho é apresentada uma revisão bibliográfica dos principais aspectos relacionados com semioquímicos presentes na oviposição dos mosquitos auxiliando no entendimento dos mecanismos de atuação dos mesmos e potencializando a aplicação destes semioquímicos como uma possível ferramenta de monitoramento e controle de Culicidae

Insecticide resistance and genetic variability in natural populations of Aedes (Stegomyia) aegypti (Diptera: Culicidae) from Colombia

Mosquito control prevails as the most efficient method to protect humans from the dengue virus, despite recent efforts to find a vaccine for this disease. We evaluated insecticide resistance and genetic variability in natural populations of Aedes aegypti (Linnaeus, 1762) from Colombia. This is the first Colombian study examining kdr mutations and population structure. Bioassays with larvae of three mosquito populations (Armenia, Calarcá and Montenegro) were performed according to the World Health Organization (WHO) guidelines, using Temephos. For the analysis of the Val1016Ile mutation and genetic diversity, we sampled recently-emerged adults from four mosquito populations (Armenia, Calarcá, Montenegro and Barcelona). Following the WHO protocol, bioassays implemented with larvae showed resistance to Temephos in mosquito populations from Armenia (77% ± 2) and Calarcá (62% ± 14), and an incipient altered susceptibility at Montenegro (88% ± 8). The RR95 of mosquito populations ranged from 3.7 (Montenegro) to 6.0 (Calarca). The Val1016Ile mutation analysis of 107 genotyped samples indicates that 94% of the specimens were homozygous for the wild allele (1016Val) and 6% were heterozygous (Val1016Ile). The 1016Ile allele was not found in Barcelona. Genetic variability analysis found three mitochondrial lineages with low genetic diversity and gene flow. In comparison with haplotypes from the American continent, those from this study suggest connections with Mexican and North American populations. These results confirm that a continuous monitoring and managing program of A. aegypti resistance in the state of Quindío is required

Insecticidal activity of three species of Guatteria (Annonaceae) against Aedes aegypti (Diptera: Culicidae)

the products of vegetal origin were assessed for bioactive substances to reduce reliance on organophosphate and pyrethroid insecticides, to which insect populations have become resistant. For this reason the aim of this study was to assess whether the essential oils of Guatteria hispida, G. blepharophylla and G. friesiana have insecticidal effect against A. aegypti under laboratory conditions. Essential oils were extracted through hydrodistillation using a modified Clevenger apparatus and analyzed by Gas Chromatography (CG-FID), Gas Chromatography coupled to Mass Spectrometry (GC-MS), and Nuclear Magnetic Resonance (NMR). the bioassays were analyzed according to the Probit model. The GC-MS and NMR analyses confirmed that the leaves of G. blepharophylla have the caryophyllene oxide as their main component; in G. friesiana the a-,b- and g-eudesmols prevail, and in G. hispida a- and b-pinene, and (E)-caryophyllene are the predominant compounds. the lethal concentrations LC50, LC95 and LC99, were respectively 85.74, 199.35 and 282.76ppm for G. hispida; 58.72, 107.6 and 138.37ppm for G. blepharophylla; and 52.6, 94.37 and 120.22ppm for G. friesiana. the oil extracted from G. friesiana presented the best insecticidal effect.Se evalúan productos de origen vegetal en busca de sustancias bioactivas que tengan la capacidad de reducir la dependencia de insecticidas organofosforados y piretroides, a los que las poblaciones de insectos se han vuelto resistentes. Por esta razón el objetivo de este estudio fue evaluar si los aceites esenciales de Guatteria hispida, G. blepharophylla y G. friesiana presentan efecto insecticida contra A. aegypti bajo condiciones de laboratorio. Los aceites esenciales se extrajeron a través de hidrodestilación por medio de un aparato tipo Clevenger, analizados por Cromatografía Gaseosa acoplada a Espectrometría de Masas (CG-EM) y Resonancia Magnética Nuclear (RMN). Los bioensayos se analizaron de acuerdo con el modelo Probit. Los análisis de (CG-EM) y (RMN) confirmaron que las hojas de G. blepharophylla presentan óxido de cariofileno como el principal componente; en G. friesiana fue a-, b- y g-eudesmol, y en G. hispida a- y b-pineno y (E)-cariofileno fueron los compuestos predominantes. La concentraciones letales CL50, CL95 y CL99 fueron respectivamente 85,74, 199,35 y 282,76ppm para G. hispida; 58.72, 107.6 y 138.37 ppm para G. blepharophylla; 52,6, 94,37 y 120,22ppm para G. friesiana. El aceite extraído de G. friesiana presentó el mejor efecto insecticida.publishe