Resumen

ALVAREZ GONZALEZ, Leslie; PONCE GARCIA, Gustavo  y  FLORES SUAREZ, Adriana. Mechanisms of Permethrin resistance in two populations of Aedes aegypti in westernVenezuela. Bol Mal Salud Amb [online]. 2016, vol.56, n.1, pp.43-52. ISSN 1690-4648.

Permethrin resistance was determined in Aedes aegypti populations from Trujillo and Zulia states using the bottle bioassay method. Insect knock-down rates during 1h of exposure were recorded and used to calculate the 50% knock-down concentration (KC₅₀) and the mortality after 24 h (LC₅₀). Knock-down and post-recovery resistance were determined by calculating the resistance factors, FRKC₅₀  and FRLC₅₀ . This was done by comparing the KC₅₀ and LC₅₀  values (obtained by regression analysis log-probit) of the field populations with a susceptible New Orleans strain. Metabolic and non-metabolic mechanisms associated with resistance were assessed by measuring the levels of the following enzymes: alpha-esterases, beta-esterases, mixed function oxidases (MFOs) and glutathione-S-transferases (GSTs) using the microplate technique. We also determined the alellic frequency of I1016 by allele specific PCR. Both populations showed a low knock-down resistance (FRKC₅₀ < 5) and moderate post-recovery resistance (FRLC₅₀  between 5 and 10). Overexpression of alpha-esterases was observed in the Loma Linda population and was significantly correlated with the LC₅₀ . The frequency of the I1016 allele was 0.1 for the Pampanito population and 0.17 for the Loma Linda population, and in the latter we also observed homozygous mutants. The existence of metabolic and non-metabolic mechanisms associated with knockdown resistance and post-recovery to permethrin in the populations studied was demonstrated. This should be taken into account before introducing these insecticides to control populations of Ae. aegypti in the region.

Palabras clave : Culicidae; chemical control; detoxification enzymes; kdr mutation.