Actividad tóxica de piretroides en una cepa experimental de lutzomyia longipalpis Lutz & Neiva 1912 (Díptera: Psichodidae) procedente del Valle del Magdalena Medio, Colombia

Abstract

For vector control L. longipalpis, foci of visceral leishmaniasis, the application of residual insecticides, particularly pyrethroids group is recommended, however, little is known about the toxicity of pyrethroids in this vector. The aim of the study was to determine in an experimental strain of L. longipalpis, toxicity, through concentration and mortality trials, the pyrethroids cyhalothrin, deltamethrin and alpha-cypermethrin. The tests were made following the guidelines of the WHO, but instead of containers exposure and impregnated papers WHO, glass bottles Wheaton 250 ml treated with 1 ml of insecticide solution in absolute alcohol were used, following the protocol of the Centers for Disease Control (CDC). Groups of 10 female L. longipalpis without blood supply were exposed in treated bottles, 5 concentrations of each pyrethroid, which caused between 5 and 100% mortality in L. longipalpis. After an hour of exposure, females were transferred to containers observation and mortality was recorded after 24 h. Each concentration was repeated 6 times. Lethal concentrations (ug / ml) that killed 50 and 95% (LC50 and LC95) of exposed females of L. longipalpis were 0.05 and 0.86 for cyhalothrin, deltamethrin 0.53 and 4.72 to 0.24 and 3.62 and for alpha-cypermethrin. Based on the LC50 obtained, the lambda is the most toxic to L. longipalpis pyrethroid, followed by alpha-cypermethrin and deltamethrin. The LC50 of cyhalothrin was 4.8 times lower than that of alpha-cypermethrin and 10.6 times less than that of deltamethrin. The discriminating Concentrations (LC99 x 2), useful in monitoring susceptibility to the three pyrethroids in populations exposed were 5.4, 22.2 and 23.4 ug / ml for lambda, alpha-cypermethrin and deltamethrin, respectively. It is expected that these data will be useful in studies of the effects of sublethal concentrations of three pyrethroids in the behavior of L. longipalpis and studies vector susceptibility to them.