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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.

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RESUMO

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.(AU)

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Objetivo Evaluar la actividad larvicida de dos fracciones etéreas de Heli opsisoppositifolia (L.) Drucey Jaegeria hirta (Lag.) Less en larvas de Aedes (Stegomyia) aegypti (L.) de 3-4 ínstar, en el municipio de Armenia, Quindio. Métodos Se realizó la colecta y análisis fitoquímico preliminar de dos especies vegetales, H. oppositifolia y J. hirta. Fueron preparadas fracciones etéreas de las dos especies. Con estas fracciones, fueron evaluadas 11 concentraciones para determinar las concentraciones letales CL50, CL90 y CL95 después de 24 y 48h. Con los resultados de las CL50,CL90 y CL95, se simuló y construyó un modelo que describe la dinámica población-concentración letal. Resultados La marcha fitoquímica preliminar permitió caracterizar en H. oppositifolia y J. hirta la presencia de: Taninos, flavonoides, quinonas, glicósidos cardiotónicos, esteroles, lactonas, terpenos, coumarinas y alcaloides. Las CL, 48 después para J. hirta (CL5024 CL9070 y CL9593 ppm) fueron menores que H. oppositifolia (CL5039, CL9077y CL9594 ppm). El ANOVA factorial confirmó esta tendencia, J. hirta (66 %, F=18.5, p<0.05) y H. oppositifolia (34 %, F=18.5, p<0.05). La simulación matemática sugiere que la aplicación cada 15 días de la CL50, y cada 30 días de las CL90 y CL95 de cualquiera de las dos especies, tienen la misma respuesta que la utilización de las CL90 y CL95 cada 30 días o la CL50 cada 15 días. Conclusión Ambas especies poseen efecto larvicida. Sin embargo, J. hirta se mostró más promisoria como futuro bioinsecticida para el control de estados inmaduros de Ae. aegypti.(AU)

Objective Evaluating the larvicidal activity of two ether factions from Asteraceae (the aster, daisy or sunflower family, i.e. Heli opsisoppositifolia (L.) Druce (oxeye, sunflower-like) and Jaegeria hirta (Lag.) Less (weed-like)) on Aedes (Stegomyia) aegypti (L.) final third instar or initial fourth instar larvae near the town of Armenia in the Quindío Department in Colombia. Methods H. oppositifolia and J. hirta plants were collected and submitted to phytochemical analysis. Ether fractions were prepared form both species to assess 11 concentrations for determining LC50, LC90 and LC95 lethal concentrations after 24 and 48h. The LC50, LC90 and LC95 results were used to create a mathematical model for describing lethal population-concentration dynamics. Results Phytochemical analysis identified tannins, flavonoids, quinones, cardiac glycosides, sterols, lactones, terpenes, courmarins and alkaloids in H. oppositifolia and J. hirta. LC after 48h regarding J. hirta (LC50 24, LC90 70 and LC95 93ppm) was lower than those for H. oppositifolia (LC50 39, LC90 77 and LC95 94 ppm). A factorial ANOVA test confirmed this trend: 66 %, F=18.5 and p<0.05 for J. hirta and 34 %, F=18.5 and p<0.05 for H. oppositifolia. The mathematical simulation model suggested that using LC50 every 15 days and LC90 and LC95 every 30 days from either of these species led to the same response compared to using LC90 and LC95 every 30 days or LC50 every 15 days. Conclusion Both species had a larvicidal effect. However, J. Hirta turned out to be more promising as an eventual bioinsecticide for controlling A. Aegypti immature states.(AU)

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OBJECTIVE: Evaluating the larvicidal activity of two ether factions from Asteraceae (the aster, daisy or sunflower family, i.e. Heli opsisoppositifolia (L.) Druce (oxeye, sunflower-like) and Jaegeria hirta (Lag.) Less (weed-like)) on Aedes (Stegomyia) aegypti (L.) final third instar or initial fourth instar larvae near the town of Armenia in the Quindío Department in Colombia. METHODS: H. oppositifolia and J. hirta plants were collected and submitted to phytochemical analysis. Ether fractions were prepared form both species to assess 11 concentrations for determining LC50, LC90 and LC95 lethal concentrations after 24 and 48 h. The LC50, LC90 and LC95 results were used to create a mathematical model for describing lethal population-concentration dynamics. RESULTS: Phytochemical analysis identified tannins, flavonoids, quinones, cardiac glycosides, sterols, lactones, terpenes, courmarins and alkaloids in H. oppositifolia and J. hirta. LC after 48 h regarding J. hirta (LC50 24, LC90 70 and LC95 93 ppm) was lower than those for H. oppositifolia (LC50 39, LC90 77 and LC95 94 ppm). A factorial ANOVA test confirmed this trend: 66 %, F=18.5 and p<0.05 for J. hirta and 34 %, F=18.5 and p<0.05 for H. oppositifolia. The mathematical simulation model suggested that using LC50 every 15 days and LC90 and LC95 every 30 days from either of these species led to the same response compared to using LC90 and LC95 every 30 days or LC50 every 15 days. CONCLUSION: Both species had a larvicidal effect. However, J. Hirta turned out to be more promising as an eventual bioinsecticide for controlling A. Aegypti immature states.

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