Estudio preliminar sobre el comportamiento de Aedes albopictus de la region central de Venezuela a insecticidas químicos / Preliminary study on the behavior of Aedes albopictus from the central region of Venezuela to chemical insecticides

Aedes albopictus es un competente vector del virus chikungunya, zika y de la mayor parte de los virus de encefalitis equina, capaz de transmitir al menos 24 arbovirus, susceptible a la infeccion (vertical y horizontalmente) por los serotipos del virus dengue. El objetivo fue realizar un estudio preliminar sobre el comportamiento frente a insecticidas organosinteticos de Ae. albopictus de diferentes localidades de tres estados centrales del pais, durante el periodo 2012-2014. Se realizaron pruebas biologicas con botellas tratadas con insecticidas, segun el metodo del CDC e igualmente evaluacion bioquimica para identificar los mecanismos de detoxificacion enzimaticos in vitro y mecanismos de resistencia in vivo con el sinergista butoxido de piperonilo (PB). Todas las cepas evaluadas presentaron sensibilidad al DDT (200 µg/mL) y cuatro de ellas a lambdacialotrina (6,25 µg/mL), solo una, Santos Michelena (SM) presento valores de sobrevivencia. Tambien esto fue observado con: malation (100 µg/mL) con una mortalidad en 30 minutos de 42,6% para Carabobo; 46,2% Distrito Capital (DC); 69,6% Zamora y 75,5% Mario Briceno Iragorry (MBI), solo resulto sensible SM. En cuanto a fenitrotion se encontraron valores de sobrevivencia con mortalidades en 30 minutos de 72,2%; para Carabobo, 30,7% DC y 45,8% MBI; solo expresaron sensibilidad Zamora y SM. En las cepas Carabobo y DC se observo el efecto sinergico FS = 3 y FS = 1,3, respectivamente. Se presume que los valores de sobrevivencia encontrados para insecticidas organofosforados pudiera asociarse con el incremento de esterasas alfa (a) y beta (b), en menor medida por la acetilcolinesterasa insensible (AChei) y las oxidasas con la sobrevivencia a lambdacialotrina en la cepa SM, lo cual podria comprobarse en estudios futuros a realizarse sobre resistencia a insecticidas. Los resultados encontrados en el presente trabajo, constituyen la base para su inicio a corto plazo en Ae. albopictus de Venezuela y la region, a fin de contribuir en la eficacia de las medidas de control quimico de esta especie de importancia medica.

Aedes albopictus is a competent vector of chikungunya virus, zika and most of the equine virus, capable of transmitting at least 24 arboviruses, susceptible to infection (vertically and horizontally) by serotypes of the dengue virus encephalitis. The objective was to conduct a preliminary study on the behavior against Ae. albopictus organosintetic insecticides from different locations in three central states of the country during the period 2012-2014. Bioassays with insecticide-treated bottles were performed according to the method of the CDC and also biochemical evaluation to identify the mechanisms of detoxification enzyme in vitro and in vivo mechanisms of resistance to the synergist piperonyl butoxide (PB). All strains tested showed sensitivity to DDT (200 µg/mL) and four of them lambdacyhalothrin (6.25 µg/mL), only one, Santos Michelena (SM) presented values of survival. This was also observed: malathion (100 µg/mL) with a mortality time (30 min) of 42.6% for Carabobo; 46.2% Capital District (DC); Zamora 69.6% and 75.5% Mario Briceno Iragorry (MBI) was sensitive only SM. As fenitrothion survival values encountered in the mortalities time (30 min) 72.2%; for Carabobo, 30.7% and 45.8% MBI DC; only expressed sensitivity Zamora and SM. In DC strains Carabobo and the synergistic effect was observed FS = 3 and FS = 1.3, respectively.It is presumed that the survival values found for organophosphate insecticides may be associated with increased esterase alpha (a) and beta (b), to a lesser extent insensitive acetylcholinesterase (ACHEI) and oxidases with survival to lambdacialotrine in strain SM , which could be verified in future studies to be carried out on insecticides resistance. The results found in the present work, constitute the basis for its short-term start in Ae. albopictus from Venezuela and the region, in order to contribute to the effectiveness of chemical control measures of this species of medical importance.

Estado de la resistencia a insecticidas organosintéticos de Aedes aegypti de Coro, estado Falcon, Venezuela / Status of resistance to organo-synthetic insecticides by an Aedes aegypti strain from Coro, Falcon state, Venezuela

Aedes aegypti es una de las especies más estudiadas en salud pública por ser vector primario en el ser humano del virus dengue, fiebre amarilla, chikungunya y zika. Se evaluó la respuesta a los insecticidas organofosforados malatión, fenitrotión, pirimifos-metil al carbamato propoxur y al piretroide lambdacialotrina en una cepa de campo denominada Coro, conformada por un pool de material (inmaduro) colectado en barriadas con alta casuística de dengue ubicadas en municipio Miranda, estado Falcón, Venezuela; en comparación con la cepa susceptible Rockefeller. Se realizaron los bioensayos en botellas tratadas con insecticidas, según el método del CDC e igualmente se identificaron los mecanismos de resistencia in vitro a través de pruebas bioquímicas. La cepa evaluada resultó resistente a malatión (45 min), fenitrotión (75 min) pirimifos-metil (75 min) con respecto a la cepa susceptible con 30, 45 y 45 min.respectivamente, con porcentajes de mortalidad en el tiempo umbral de 89,2% malatión; 55,7% fenitrotión; 56,6%, pirimifos-metil. Se encontró susceptibilidad al carbamato propoxur y al piretroide lambdacialotrina. En cuanto a las pruebas bioquímicas se encontraron valores elevados para esterasas alfa (α) y beta (β) con diferencias estadísticamente significativas (P<0,05) al comparar con la cepa susceptible. La acetilcolinesterasa inhibida (Achei) a pesar de encontrar diferencias significativas con la cepa Rockefeller los valores están por debajo de la misma. La resistencia de la cepa Coro a los insecticidas organofosforados parece asociarse con el incremento de las esterasas alfa (α) y beta (β). Los resultados obtenidos representan un aporte valioso para monitorear la resistencia de Ae. aegypti a nivel local dentro de un programa de manejo integrado de vectores.

Aedes aegypti is one of the most studied species in public health as the primary vector in humans the dengue, chicunguya, zyca virus and yellow fever. Response to organophosphorus insecticides malathion, fenitrothion, methyl-pirimiphos and carbamate propoxur was evaluated and the pyrethroid lambda-field strain called Coro, made up of a pool of material (immature) collected in neighborhoods with high casuistry of dengue Coro located in Miranda municipality, Falcón state, Venezuela; compared with the susceptible Rockfeller. Bioassays in insecticide-treated bottles were performed according to the method of the CDC and also the mechanisms of resistance in vitro were identified by biochemical tests. The resistant strain was evaluated to malathion (45 min), fenitrothion (75 min) methyl-pirimiphos (75 min) compared to the susceptible strain with 30, 45 and 45 min respectively, with mortality rates of 89 time threshold, 2% malathion, fenitrothion 55.7%, 56.6%, pirimiphos-methyl. Susceptibility to propoxur carbamate and pyrethroid lambda was found. As for the high values for biochemical tests esterases alpha (α) and beta (β) with statistically significant differences (P< 0.05) compared with the susceptible strain were found. Inhibited aceltilcholinesterase (Achei) despite significant differences with the Rockefeller strain values are below the same acetylcholinesterase. Falcon resistance to organophosphate insecticides strain appears to be associated with increased alpha esterases (α) and beta (β). The results represent a valuable contribution to monitor the resistance of Ae. aegypti locally within a program of integrated vector management.