ABSTRACT
Introducción: la aparición de casos de malaria en zonas donde se creía controlada, como lo es la Región Autónoma Atlántica Norte en Nicaragua, se debe a múltiples factores como el costo de los productos químicos para el control vectorial, zonas de difícil accesibilidad y altos índices de pobreza. Recientemente existe un marcado interés en disminuir la incidencia y prevalencia de la malaria en esta área, mediante la producción y aplicación de alternativas biológicas de control. Objetivos: establecer y estandarizar la cría de Romanomermis culicivorax para la producción masiva en condiciones de laboratorio y su utilización en criaderos naturales para reducir la población de Anopheles albimanus en 3 municipios de la Región Autónoma Atlántica Norte. Métodos: se utilizaron cultivos de una cepa de Romanomermis culicivorax provenientes del Instituto de Medicina Tropical Pedro Kourí de La Habana, Cuba. El establecimiento y la producción de esta cepa se hizo siguiendo la metodología descrita por especialistas cubanos. El trabajo se realizó en 7 criaderos de 5 barrios pertenecientes a los municipios Puerto Cabezas, Waspam y Rosita, desde noviembre de 2009 a marzo de 2011. Resultados: se estableció y estandarizó la cría del nematodo, utilizando la dosis de infestación de 7:1 (7 pre-parasíticos por larva) en condiciones de laboratorio. La dosis de aplicación en los criaderos fue 1 000 pre-parasíticos/m²,demostrando ser adecuada para las condiciones de campo. Se lograron porcentajes de reducción elevados y en menor tiempo en los municipios Waspam y Rosita. Se demostró la permanencia del nematodo en los criaderos. Conclusiones: se establece por primera vez y con éxito la producción masiva de Romanomermis culicivorax en Nicaragua. Los resultados en el terreno demostraron la eficiencia de este nematodo para controlar densidades larvales de Anopheles albimanus, lo cual constituye una alternativa de control vectorial(AU)
Introduction: the emergence of malaria cases in areas where the disease was thought to be controlled, such as the North Atlantic Autonomous Region in Nicaragua, is due to a variety of factors, such as the cost of chemicals for vector control, the inaccessibility of areas and the high rates of poverty. A marked interest has recently arisen in reducing the incidence and prevalence of malaria in the region by developing and implementing biological control alternatives. Objectives: establish and standardize the breeding of Romanomermis culicivorax for mass production under laboratory conditions and for its use in natural breeding sites to reduce the population of Anopheles albimanus in three municipalities of the North Atlantic Autonomous Region. Methods: the study was based on cultures of a Romanomermis culicivorax strain obtained from Pedro Kourí Tropical Medicine Institute in Havana, Cuba. The strain was established and produced following the methodology described by Cuban specialists. The research was conducted at 7 breeding sites from 5 districts in the municipalities of Puerto Cabezas, Waspam and Rosita, from November 2009 to March 2011. Results: breeding of the nematode was established and standardized with a 7:1 infestation dose (7 preparasites per larva) under laboratory conditions. The application dose at breeding sites was 1 000 preparasites/m², which proved to be appropriate for field conditions. High reduction percentages were obtained. These were achieved in a shorter time in the municipalities of Waspam and Rosita. It was found that the nematodes remained at the breeding sites. Conclusions: successful mass production of Romanomermis culicivorax is established for the first time in Nicaragua. Field results show the efficiency of this nematode to control larval densities of Anopheles albimanus, constituting a vector control alternative(AU)
Subject(s)
Pest Control, Biological/methods , Malaria/prevention & control , Mermithoidea/parasitologyABSTRACT
Introducción: la aparición de casos de malaria en zonas donde se creía controlada, como lo es la Región Autónoma Atlántica Norte en Nicaragua, se debe a múltiples factores como el costo de los productos químicos para el control vectorial, zonas de difícil accesibilidad y altos índices de pobreza. Recientemente existe un marcado interés en disminuir la incidencia y prevalencia de la malaria en esta área, mediante la producción y aplicación de alternativas biológicas de control. Objetivos: establecer y estandarizar la cría de Romanomermis culicivorax para la producción masiva en condiciones de laboratorio y su utilización en criaderos naturales para reducir la población de Anopheles albimanus en 3 municipios de la Región Autónoma Atlántica Norte. Métodos: se utilizaron cultivos de una cepa de Romanomermis culicivorax provenientes del Instituto de Medicina Tropical Pedro Kourí de La Habana, Cuba. El establecimiento y la producción de esta cepa se hizo siguiendo la metodología descrita por especialistas cubanos. El trabajo se realizó en 7 criaderos de 5 barrios pertenecientes a los municipios Puerto Cabezas, Waspam y Rosita, desde noviembre de 2009 a marzo de 2011. Resultados: se estableció y estandarizó la cría del nematodo, utilizando la dosis de infestación de 7:1 (7 pre-parasíticos por larva) en condiciones de laboratorio. La dosis de aplicación en los criaderos fue 1 000 pre-parasíticos/m²,demostrando ser adecuada para las condiciones de campo. Se lograron porcentajes de reducción elevados y en menor tiempo en los municipios Waspam y Rosita. Se demostró la permanencia del nematodo en los criaderos. Conclusiones: se establece por primera vez y con éxito la producción masiva de Romanomermis culicivorax en Nicaragua. Los resultados en el terreno demostraron la eficiencia de este nematodo para controlar densidades larvales de Anopheles albimanus, lo cual constituye una alternativa de control vectorial(AU)
Introduction: the emergence of malaria cases in areas where the disease was thought to be controlled, such as the North Atlantic Autonomous Region in Nicaragua, is due to a variety of factors, such as the cost of chemicals for vector control, the inaccessibility of areas and the high rates of poverty. A marked interest has recently arisen in reducing the incidence and prevalence of malaria in the region by developing and implementing biological control alternatives. Objectives: establish and standardize the breeding of Romanomermis culicivorax for mass production under laboratory conditions and for its use in natural breeding sites to reduce the population of Anopheles albimanus in three municipalities of the North Atlantic Autonomous Region. Methods: the study was based on cultures of a Romanomermis culicivorax strain obtained from Pedro Kourí Tropical Medicine Institute in Havana, Cuba. The strain was established and produced following the methodology described by Cuban specialists. The research was conducted at 7 breeding sites from 5 districts in the municipalities of Puerto Cabezas, Waspam and Rosita, from November 2009 to March 2011. Results: breeding of the nematode was established and standardized with a 7:1 infestation dose (7 preparasites per larva) under laboratory conditions. The application dose at breeding sites was 1 000 preparasites/m², which proved to be appropriate for field conditions. High reduction percentages were obtained. These were achieved in a shorter time in the municipalities of Waspam and Rosita. It was found that the nematodes remained at the breeding sites. Conclusions: successful mass production of Romanomermis culicivorax is established for the first time in Nicaragua. Field results show the efficiency of this nematode to control larval densities of Anopheles albimanus, constituting a vector control alternative(AU)
Subject(s)
Malaria/prevention & control , Pest Control, Biological/methods , Mermithoidea/parasitologyABSTRACT
En junio de 1996, en el Estado de Oaxaca, Mexico, se expusieron larvas de mosquito de la especie Aedes aegypti (Linneo) a los preparasitos infectivos del nematodo Romanomermis culicivorax, Ross y Smith, en condiciones de laboratorio y de campo. Para los experimentos de laboratorio se utilizaron larvas en estadio I-IV, colectadas en reservorios naturales. Los experimentos se realizaron por triplicado, con 100 larvas de cada estadio larvario por experimento, y se probaron tres dosis de aplicacion: 5:1, 10:1 y 15:1 (5, 10 o 15 preparasitos por larva de mosquito). Para los estudios de campo se tomaron 13 criaderos naturales de A. aegypti con larvas en estadio I-IV y se aplico una dosis de 15:1 por cada criadero. De acuerdo con los resultados obtenidos en los experimentos de laboratorio, se observo un aumento de la infestacion media de las larvas a medida que aumentaba la dosis de aplicacion desde 5:1 hasta 15:1. Para la dosis de 10:1, la tasa de parasitismo alcanzo valores de 100, 100, 85 y 74 por ciento en las larvas en estadio I, II, III y IV, respectivamente, y, para la dosis de 15:1, valores de 100, 100, 90 y 79 por ciento, respectivamente. Los resultados de las pruebas de campo con la aplicacion de una dosis de 15:1 en los 13 reservorios naturales proporcionaron elevadas tasas de parasitismo, con valores entre 80-98 por ciento, lo que demostro la susceptibilidad de esta especie de mosquito al parasitismo por R. culicivorax en el Estado de Oaxaca, Mexico
Subject(s)
Mermithoidea/parasitology , Aedes/parasitology , Laboratories , Case-Control Studies , MexicoABSTRACT
In September and November 1996 Romanomermis iyengari Welch, a parasite of larval mosquitoes, was released in 44 natural larval habitat sites of Anopheles pseudopunctipennis Theobald in an attempt to reduce the larval populations of this important malaria vector. The selected treatment sites ranged in size from 5 to 500 m2. The study was carried out in Pochutla District of Oaxaca State, on the Pacific coast of Mexico. Chemical pesticides to reduce vector populations have been the principal tool in malaria suppression campaigns. However, the excessive use of these chemicals has created pesticide resistance and other serious collateral problems. Therefore, a biological control project using agents that are pathogens of Anopheles larvae was initiated in 1996. The principal objective was to establish mass rearing capacities for R. iyengari. Detailed methodology for rearing and introducing these nematodes into mosquito larval habitats was established at the National Polytechnic Institute of Oaxaca State. Before application of the parasites to larval habitats, site characteristics were determined, including size, depth, aquatic vegetation, salinity, pH, conductivity, temperature, and pretreatment larval density. With a compressed air sprayer, infective mermithid parasites were released at rates of either 2,000 or 3,000/m2, and the parasites produced high levels of infection. Anopheles populations were sampled 72 h posttreatment, and the larvae obtained were taken to the laboratory and examined through microscopic dissection to determine infection levels and mean parasitism. Nematode parasitism ranged from 85 to 100% at all the treatment sites, even though no previous information concerning field parasitism of An. pseudopunctipennis by R. iyengari has been reported. In addition, a significant reduction of mosquito larval density at the treatment sites was found five days after the nematode application. Levels of parasitism were indicative of the number of mosquito larvae killed by the treatment since infected larvae never progressed to the pupal stage. Results from sampling nine of the sites 2 months after the initial application of nematodes indicated that a high number of mosquito larvae were infected by parasites that had emerged from eggs previously deposited in the stratum. This work suggests the potential of this mermithid to reduce An. pseudopunctipennis populations in Oaxaca State.
Subject(s)
Anopheles/parasitology , Malaria/parasitology , Mermithoidea/parasitology , Mosquito Control , Animals , Antiparasitic Agents , Disease Vectors , Epidemiologic Methods , Humans , Larva/drug effects , Malaria/epidemiology , Malaria/prevention & control , Mexico/epidemiology , Pesticides/pharmacologyABSTRACT
About 80 species of mermithids parasitic in blackflies have been recorded from the Ethiopian and Holarctic regions. Species of three genera, Mesomermis, Gastromermis and Isomermis, are most common parasites of blackflies. Critical periods during the ontogenesis of all mermithids are associated with the penetration of infective larvae into the host and protective reactions of the later. Intraspecific hybridization of the parasites is recommended in order to increase the effectiveness of mermithids as agents of biological control of blackflies.
Subject(s)
Diptera/parasitology , Mermithoidea/parasitology , Pest Control, Biological , Animals , Biology , Female , Hybridization, Genetic , Larva/parasitology , Mermithoidea/classification , USSRABSTRACT
A double infection of the larvae of Aedes flavescens and A. cantans with Thelohania opacita and larvae of Mermithidae was established. The double infection is not accompanied by the rise of pathogenic effect of the parasites on the hosts. Mermithids parasitizing mosquitoes infected with microsporidians inhibit the development of Protozoa. The inhibition degree depends on the duration of contacts of coparasites as well as on the developmental phase of microsporidians at the moment of penetration of nematodes.
