Maritza Rondón

Effect of Environmental Disturbance on the Population of Sandflies and Leishmania Transmission in an Endemic Area of Venezuela

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.

Distribution of Vector Sandflies Leishmaniasis from an Endemic Area of Venezuela

Background: Sandflies distribution is associated with different factors linked to climate changes that might cause alterations in their distribution and increase the risk of leishmaniasis transmission. Present work aims to determine the composition and structure of sandflies from an endemic area of Venezuela and its relationship to environmental variables. Method: Various locations were sampled, four sandflies capture methods were used and weather variables capture site, altitude, temperature and relative humidity were recorded. Specimens were identified. Abundance, dominance and species richness was estimated and multivariate analysis was performed. Results: L. youngi is the main species associated with sandfly transmission of Leishmania in the highlands (≥ 600 m.asl), while L. gomezi, L. ovallesi and L. walkeri were found in lower altitudes and higher temperatures, prevailed in the lowlands (≤ 600 m. asl). Sandflies in the warmer lower altitudes showed greater species richness, greater biodiversity, and lower dominance than those at higher altitudes. Conclusion: The sandflies composition and structure changed according to climate factors, showing a speciesspecific dispersion pattern. Relevant data for sandfly vectors species of Leishmania are provided that should be considered in implementing control and prevention measures

Insecticide Activity of Ageratina jahnii and Ageratina pichinchensis (Asteraceae) against Lutzomyia migonei (Diptera: Psychodidae)

Background: Insects are mostly pathogens transmitters, thus the necessity of finding effective bioinsecticides to combat them. In the present investigation, the insecticide activity of Ageratina jahnii and Ageratina pichinchensis (Asteraceae) essential oils, methanol, and aqueous extracts was evaluated against Lutzomyia migonei (Diptera: Psychodidae) females, Leishmania transmitters, a wide distributed parasitosis in Latin America. Materials and Methods: All extracts were prepared by maceration at room temperature, and essential oils were obtained by hydrodistillation process. Females of L. migonei were used in the bioassays using the adulticide test in pots. Results: Essential oils from both assayed plant species showed 100% of L. migonei mortality at 48 h of exposure at the concentration of 10 mg/ml. A. jahnii essential oil exhibited the following values, LD50 = 0.39 mg/ml, LD90 = 1.57 mg/ml, LD95 = 2.31 mg/ml, and LD99 = 4.80 mg/ml while for A. pichinchensis essential oil values were LD50 = 0.31 mg/ml, LD90 = 0.99 mg/ml, LD95 = 1.38 mg/ml, and LD99 = 2.55 mg/ml. Conclusion: Higher toxicity was observed with A. pichinchensis essential oil against L. migonei, comparing to A. jahnii oil. Two new plant species are being reported, showing bioactive properties against common tropical disease vectors such as L. migonei, hence, opening possibilities to a more environmental friendly control.