ABSTRACT
Hylesia metabus Cramer es una polilla considerada un problema de salud pública debido a que las hembras adultas liberan setas urticantes produciendo dermatitis y prurito intenso en el hombre. En la región nororiental de Venezuela, en dos localidades (Mapire y Pedernales) y durante seis ciclos, se registró el parasitismo natural sobre esta polilla. Para ello, se colectaron pupas en el campo y se mantuvieron bajo condiciones de laboratorio (27ºC, 65 por ciento humedad relativa y ciclo invertido 12L:12O) hasta la eclosión de los adultos. Se determinó que en Mapire el parasitismo aumentó de 33,0 por ciento a 91,1 por ciento en tres ciclos consecutivos estudiados y los principales parasitoides fueron los Diptera: Belvosia spp. (Tachinidae) y Sarcodexia lambens (Sarcophagidae) y diversas especies de Hymenoptera (Ichneumonidae, Chalcidae, Perilampidae, Eulophidae). En Pedernales en tres ciclos consecutivos el parasitismo disminuyó de 29,5 por ciento a 16,1 por ciento, el parasitoide más abundante fue Belvosia spp., con niveles de parasitismo entre 70,7 por ciento y 96,2 por ciento. Solamente durante el tercer ciclo, la contribución de otro parasitoide resultó significativa y correspondió a Neotheronia sp. (Hymenoptera: Ichneumonidae), que causó 27,1 por ciento de parasitismo. Todos los parasitoides obtenidos fueron koinobiontes larva-pupa. Las variaciones poblacionales de H. metabus y sus parasitoides en las áreas estudiadas son discutidas. Belvosia spp. y Sarcodexia lambens son potenciales parasitoides a ser usados en programas de manejo integrado de este insecto plaga.
The moth Hylesia metabus Cramer is considered a public health pest due to the release of urticating hairs by adult females during periodic invasions of towns and villages, producing dermatits in humans. We reported natural parasitism levels for this moth during six life cycles in two localities in northeastern Venezuela. Pupae were collected in the field and maintained under laboratory conditions (27ºC, 65 percent RH, 12L:12D photoperiod) until eclosion. In Mapire, parasitism increased from 33.0 percent to 91.1 percent in the three cycles studied, with the dipterans Belvosia spp. (Tachinidae) and Sarcodexia lambens Wiedemann (Sarcophagidae) and species from Ichneumonidae, Chalcidae, Perilampidae and Eulophidae being the most common. In Pedernales, parasitism decreased from 29.5 percent to 16.1 percent, and Belvosia spp. was the most abundant parasitoids, reaching parasitization levels between 70.7 percent and 96.2 percent. A significative parasitization by Neotheronia sp. (Hymenoptera: Ichneumonidae) (27.1 percent) occurred only in third life cycle. All natural enemies observed were koinobionts, larval-pupa parasitoids. The variations in the populations of H. metabus and its parasitoids in the areas studied are discussed. Belvosia spp. and S. lambens may have potential for use in integrated management program of H. metabus.
Subject(s)
Animals , Lepidoptera/parasitology , Larva/parasitology , Pest Control, Biological , Pupa/parasitology , VenezuelaABSTRACT
Extracts of propolis samples collected in Brazil and Bulgaria were assayed against four Leishmania species - Leishmania amazonensis, L. braziliensis, L. chagasi from the New World, and L. major from the Old World - associated to different clinical forms of leishmaniasis. The composition of the extracts has been previously characterized by high temperature high resolution gas chromatography coupled to mass spectrometry. Considering the chemical differences among the extracts and the behavior of the parasites, it was observed significant differences in the leishmanicidal activities with IC50/1 day values in the range of 2.8 to 229.3 µg/ml . An overall analysis showed that for all the species evaluated, Bulgarian extracts were more active than the ethanol Brazilian extract. As the assayed propolis extracts have their chemical composition determined it merits further investigation the effect of individual components or their combinations on each Leishmania species
Subject(s)
Animals , Anopheles , Bacillus thuringiensis , Larva , Pest Control, Biological/methods , Sodium ChlorideABSTRACT
Actualmente existen diferentes productos a base de Bacillus spp. que tienen un efecto larvicida sobre Anopheles spp., vectores de la malaria. Sin embargo, su eficacia es variable dependiendo de la especie blanco y las condiciones ambientales. Se evaluó la efectividad del producto Griselesf® (Bacillus sphaericus 2362) como controlador biológico de Anopheles aquasalis, principal vector de malaria en el estado Sucre, en dos ocasiones bajo las mismas condiciones de laboratorio, en el año 2002 y luego en el 2006. Se prepararon soluciones del producto a concentraciones de 1, 5, 10, 50 y 100 ppm (año 2002) y 5, 25, 50, 75 y 100 ppm (año 2006), en 600 mL de agua potable. Luego se trasvasaron 100 mL de cada una de las soluciones en envases plásticos de 250 mL y se colocaron 10 larvas de los estadíos tercero tardío o cuarto temprano en cada uno de los recipientes. En el 2002, a los 48 horas en 100 ppm el Griselesf® había matado solamente 0,84% de la población aumentando a 25% a las 72 horas. En el 2006, en 100 ppm, hubo mortalidades de 6,67 y 11,67% de las poblaciones de las larvas a las 48 y 72 horas respectivamente. Los resultados sugieren que Griselesf® no es efectivo contra las larvas de An. aquasalis del estado Sucre.
Subject(s)
Anopheles , Bacillus , Malaria/prevention & control , Environmental Health , VenezuelaABSTRACT
Se presenta la distribución fisiográfica de los vectores de malaria en Venezuela, basada en la revisión de trabajos publicados y consultas a especialistas a partir de los primeros registros disponibles desde 1910 hasta el presente. La información recopilada fue plasmada en mapas realizados con el programa Surfer (V. 8.01) y ubicados en las diferentes ecoregiones identificadas para Venezuela. El presente trabajo constituye un primer esfuerzo por crear una base de datos sobre la distribución de anofelinos vectores de malaria en Venezuela y ponerla a disposición del MSDS y la comunidad científica
Subject(s)
Animals , Disease Vectors , Malaria , Biological Specimen BanksABSTRACT
The symptoms of Anopheles aquasalis larvae naturally infected by a microsporidium, and the ultrastructure of the infecting spores is described. The larvae were maintained under laboratory conditions in salt concentrations of 10 g/l and 20 g/l of water. Daily recordings of the mortality of the larvae were made and the dates of change of instar were noted. Infected larvae were processed for transmission electronic microscopy using conventional methods at pH 7.2 and 260 mOsm/l. The infection by the microsporidia was positively correlated with an increase in the mean duration of the fourth instar of 2.88 to 6.33 days in 10 g/l of salt and of 2.47 to 6.14 days in 20 g/l of salt...
Subject(s)
Animals , Female , Anopheles , Microsporida , Larva , Microscopy, Electron , Microsporida , Survival Analysis , VenezuelaABSTRACT
Lepidopteran larvae may be attacked by different viruses, many of which belong to the Baculoviridae family. Whilst studying the ultrastructure of the neck gland in Dione junio larvae we found that in later instars the larvae showed symptoms of attack by two types of virus. The glands were prepared for optical and electron microscopy using sodium cacodylate buffer and standard procedures (0.1M, pH 7.2). The neck gland is composed of two oval internal sacks which communicate with the exterior via an extracellular channel. Each sack contains, in its external region, cells with large, irregular nuclei and a dense cytoplasm containing numerous small mitochondria. In infected larvae, the tissues are damaged and the nuclear polyhedrosis virus can be observed in several of the nuclei. In the cytoplasm another "rickettsia type" virus, may be observed. The pathogenic viruses present in D. junio larvae could be studied as potential biological controls of this pest.