Resumen

ALVAREZ GONZALEZ, Leslie et al. Mechanisms associated with knockdown resistance to deltamethrin in Aedes aegypti from western Venezuela. Bol Mal Salud Amb [online]. 2014, vol.54, n.1, pp.58-67. ISSN 1690-4648.

The biochemical and molecular mechanisms associated with resistance to deltamethrin were determined in female Aedes aegypti taken from different mosquito populations captured in Trujillo, Lara and Tachira states. Individuals from each population were subjected to 1 h of exposure to deltamethrin using the CK₅₀ previously determined by the bottle bioassay. The mosquitoes were then placed in containers free from insecticide and separated into 4 phenotypes: mosquitoes that were not knocked down after 1 h of exposure, those that recovered 4 h after exposure, those that were still alive 24 h after exposure and those that were dead at 24 h. Each of the mosquitoes in these groups was then dissected to separate the head-thorax, and abdomen. Biochemical tests were performed on the head-thorax to determine the presence of resistance-related enzymes including: α-and β-esterases, glutathione S-transferase and insensitive acetylcholinesterase. The abdomen was used for molecular tests to amplify the specific allele Val 1016 and Ile 1016. The quantities of detoxifying enzymes increased between 4 and 24 h after exposure to deltamethrin in mosquitoes from most of the populations tested although no significant differences between these and the susceptible New Orleans strain (NO) were found, except for mosquitoes from the Ureña population which showed a significant increase in β-esterase with higher values in the "survivors" phenotype compared to the "dead" phenotype at 24 h. The wild genotype V1016/V1016 prevailed over the heterozygous and homozygous mutants in the four phenotypes in the majority of the populations studied, with exception of the Ureña population where the resistant homozygote I1016/I1016 was the predominant genotype. The V1016I mutation was associated with the knockdown resistance observed in the evaluated populations emphasizing the importance of the early detection of this and other mutations in the sodium channel which have been linked with resistance to pyrethroids. These aspects should be considered before applying deltamethrin to control these Ae. Aegypti populations.

Palabras clave : deltamethrin; knockdown resistance; mutation; sodium channel; enzimes.

        · resumen en Español     · texto en Español     · Español ( pdf )