The exploitation of new wilderness areas with crops is increasing and traditional crop substitution has been modified by new more productive crops. The results show the anthropogenic disturbance effect on the sandflies population and Leishmania transmission in endemic areas of Venezuela. Three agroecosystems with variable degrees of ecological disturbance, forest (conserved), cacao (fragmented), and orangery (disturbed), were selected. Four methods to sandfly capture were used; the specimens were identified and infected with Leishmania. Diversity, population structure, ANOVA, Tukey test, and simple correlation analysis were carried out. Shannon traps were able to capture 94.7% of the total sandflies, while CDC light traps, Sticky traps, and direct suction just captured 2.2%, 1.2%, and 0.9%, respectively. The results showed the effect of ecological disturbance degree on the composition of sandflies and population structure, revealing a dominance level increased but decreased on the diversity and richness of sandflies species in the greatest ecological disturbance area in relation to areas with less organic disturbance. Environments more disturbed cause adaptability of certain species such as Lutzomyia gomezi and Lutzomyia walkeri. These changes on the composition of sandflies population and structure emerging species could cause increasing of leishmaniasis transmission.
Introducción. La leishmaniasis es un grave problema de salud pública en muchas partes de América. Las poblaciones expuestas a la leishmaniasis carecen de información de la enfermedad, razón por la cual es necesario realizar intervenciones y evaluaciones educativas que contribuyan a que el control tenga un mayor impacto. Objetivo. Determinar el nivel de conocimientos y prácticas sobre la leishmaniasis tegumentaria y la fauna de flebótomos en las comunidades endémicas de Bolero Alto y Bajo del municipio Pinto Salina del Estado Mérida, Venezuela, entre septiembre de 2006 y julio de 2007. Materiales y métodos. Se elaboró una encuesta en la cual se incluyeron aspectos epidemiológicos, de prevención y de control de la leishmaniasis. Se aplicaron a personas mayores de siete años en viviendas seleccionadas aleatoriamente. También se realizaron capturas intradomiciliarias y peridomiciliarias de flebotominos vectores. Resultados. Más del 68% de los individuos de las comunidades poseía un nivel de conocimientos considerado como insuficiente; los aspectos de mayor desconocimiento fueron en relación con la transmisión y la prevención. Se detectaron siete especies de Lutzomyia de importancia epidemiológica: L youngi, L. ovallesi, L. gomezi, L. walkeri, L. panamensis, L. punctigeniculata y L. venezuelensis. Las especies predominantes para ambas comunidades fueron L. youngi con más del 55% y L. ovallesi con más del 24% del total de especímenes capturados. Conclusión. Se determinó un bajo nivel de conocimientos sobre la leishmaniasis en los pobladores de las comunidades endémicas estudiadas, lo cual se debe tener en cuenta en el desarrollo de alternativas educativas de impacto en el control complementario de la enfermedad. Las mismas deben dirigirse a cubrir las deficiencias de conocimientos más acentuadas en la población, enfocadas a evitar las picaduras del insecto vector.
Leishmaniasis is a public health problem that has been increasing year by year, with the further difficulty that an efficient control system is not available. Therefore, it is necessary to search for less contaminating and dangerous alternatives for controlling Leishmania transmitting sandflies. The purpose of this study was to evaluate the activity of Monticalia greenmaniana (Asteraceae) extracts and essential oil as an adulticide against Lutzomyia migonei (Diptera: Psychodidae) females, from a laboratory colony, in experimental conditions. Dry aerial parts of M. greenmaniana (Hieron) Jeffrey were used. Methanolic and aqueous extracts were prepared, and essential oil was obtained by hydrodistillation. Adulticide tests in pots, adulticide tests in cages, and knocked-down effects were determined. The results obtained demonstrated that methanolic and aqueous extracts produced adulticide activity. The essential oil from M. greenmaniana was proved to be the most toxic against L. migonei, with a 95 % death rate at a concentration of 0.01 mg/ml during a 1-h exposure. The essential oil showed a DL50 = 0.0050 and DL98 = 0.0066 mg/ml. The methanolic extract was DL50 = 0.130 and DL98 = 1.016 mg/ml, and the aqueous extract, DL50 = 0.487 and DL98 10.924 mg/ml. The knocked-down effect for the M. greenmaniana oil showed a KDTL50 = 48.6 and KDTL98 = 90.1 min. It was concluded that the essential oil from M. greenmaniana showed a strong insecticide effect against L. migonei females, which encourages us to continue these studies in search for control alternatives against sandflies.
Repellent activity of plant essential oils against bites of Lutzomyia migonei (Diptera: Psychodidae). Natural repellents from plant extracts have demonstrated good efficacy against bites of some insect species. The present study evaluated the repellent effect of essential oils extracted from 8 plants species against bites of Lutzomyia migonei, the Leishmania vector. The essential oils were extracted by steam destillation in Clevenger chamber, from the following plants: Hyptis suaveolens, Pimenta racemosa, Piper marginatum, Monticalia imbricatifolia, Pseudognaphalium caeruleocanum, Espeletia shultzii, Plecthranthus amboinicus and Cinnamomun zeylanicum. Repellency tests were performed under laboratory conditions by the human hand method in cage assays, using female colonies of L. migonei. The more effective oils were tested at variable concentrations on different volunteers. The protection percentage and time were calculated. The results showed what oils of P. caeruleocanum and C. zeylanicum were the most effective. Although P. amboinicus oil also had repellent effect showed an irritant effect. The oils P. marginatum, H. suaveolens and P. racemosa showed no repellent effect, while the rest of oil extracts showed significant repellency in variable degrees. P. caeruleocanum and C. zeylanicum oils provided the 95% protection against bites of L. migonei for 3h. The P. caeruleocanum oil showed the greatest protection time, with a mean over 4h and 3h at concentrations of 50% and 10% respectively. The results suggest that the P. caeruleocanum oil could represent a potential natural repellent against Leishmania vectors.
La leishmaniasis constituye un grave problema de salud pública en diferentes partes del mundo. Es conocido que los efectos del calentamiento global han aumentado en los últimos años, con la consecuente modificación, a corto y largo plazo, de los hábitats de los flebotominos, lo que potencialmente puede impactar en la transmisión de la leishmaniasis. En el presente trabajo se evaluó el efecto del cambio climático en la distribución geográfica de los flebotominos transmisores de la leishmaniasis cutánea, en Mérida, Venezuela. Para el análisis se tuvieron en cuenta cuatro especies vectoras Lutzomyia youngi, L. gomezi, L. ovallesi y L. walkeri y se usó un modelo atmósfera-océano Hadcm3, bajo la premisa de cambio climático en un escenario pesimista A2, con proyecciones para los años 2020, 2050 y 2080. Los resultados del modelo mostraron para L. youngi un incremento en su distribución, para L. gomezi cambios y desplazamiento en su distribución potencial futura, para L. ovallesi se mostró como la especie que puede ser más afectada por el aumento de la temperatura, con predicciones de cambios en su distribución futura, y para la distribución de L. walkeri no se mostró afectación por el cambio climático. Por otro lado, el modelo recreó escenarios de cambio climático, con predicciones de solapamiento de las principales especies transmisora, en los municipios de mayor densidad poblacional, lo que sugiere un mayor riesgo de transmisión de la leishmaniasis en el estado Mérida en los próximos años. Los mapas generados proporcionan información relevante para alertar sobre cambios en los patrones de transmisión de la leishmaniasis, además serán una herramienta útil para los entes de control y prevención.
Females of the sand fly Lutzomyia ovallesi (Ortiz) (Diptera: Psychodidae) were fed with blood from various species of vertebrates and analyzed to determine energy reserves under laboratory conditions. L. ovallesi specimens were allowed to artificially feed to satiation through chicken membranes on blood from horse, dog, cow, chicken, goat, pig or human. Caloric reserves were calculated spectrophotometrically after females were homogenized in a solution of sodium dichromate and sulfuric acid. The caloric content of L. ovallesi varied according to the type of vertebrate blood on which it had fed. The highest content (cal/insect) was found in females fed on human blood (0.33), followed in decreasing order by dog, pig, cow, chicken, goat and horse (0.26). Statistical analysis showed significant differences (P < 0.05) among sources. The results showed that human and dog blood meals were more nutritionally efficient. The most inefficient diet for L. ovallesi was horse blood manifested by its poor nutritional quality.
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