Pyrethroid Insecticide-Resistant Strain of Aedes Aegypti From Cuba Induced by Deltamethrin Selection

Abstract

A sample of Aedes aegypti L. from Santiago de Cuba with a high level of deltamethrin resistance (113.7 x at the 50% lethal concentration [LC50]), was subjected to deltamethrin selection to determine the capacity of this population to evolve higher resistance under intensive laboratory selection pressure, to characterize that resistance, to attempt to identify some of the mechanisms involved, and to use it as a reference strain for future molecular research. High resistance developed after 12 generations of selection (1,425 x). After selection for 12 generations with deltamethrin, the Santiago de Cuba colony (SAN-F12) showed little or no cross-resistance to the organophosphates evaluated, but high cross-resistance was observed for all the pyrethroids in larvae from this strain: lambdacyhalothrin (197.5 x), cypermethrin (45 x), and cyfluthrin (41.2 x). Adult bioassays reveal that a SAN-F12 strain was resistant to the pyrethroid and the organochlorine dichlorodiphenyltrichloroethane (DDT). Synergism tests implicated detoxifying esterase or glutathione S-transferase (GST) and monooxygenase in pyrethroid resistance. Biochemical tests reveal that acetylcholinesterase was not involved in deltamethrin resistance. The frequency of GST enzyme increased from 0.43 in Santiago de Cuba to 0.88 in SAN-F12. Esterase frequency increased from 0.12 in Santiago de Cuba to 0.63 in SAN-F6 and it diminished to 0.38 in SAN-F12. The polyacrylamide gel electrophoresis and inhibition study suggests the presence of elevated esterase activity not associated with pyrethroid resistance. The presence of both DDT and pyrethroid resistance in the SAN-F12 strain suggests the presence of a knockdown (Kdr)-type resistance mechanism, although the frequency of this mechanism was low. Resistance to deltamethrin could be associated with esterase or GST mechanisms, and more investigation is required. This information contributes to the improvement of resistance management strategies in the Cuban Ae. aegypti control program.

Point mutations in domain II of the voltage-gated sodium channel gene in deltamethrin-resistant Aedes aegypti (Diptera: Culicidae)

“…Insecticides have frequently been sprayed using fogging machines to kill adult mosquitoes in areas where dengue-infected patients were reported. Pyrethroid insecticides, such as deltamethrin and permethrin, are one of the four major groups of insecticides (e.g., organophosphate, organochlorine, pyrethroid, and carbamate), and are com-monly used and widely accepted in agricultural and vector control programs (Chareonviriyaphap et al, 2002;Enayati et al, 2003;Rodriguez et al, 2005). They have also been used to treat bed nets, curtains, and as indoor residual sprays (Chareonviriyaphap et al, 2003) because they have knockdown effects, high insecticidal potency, no bioaccumulation, and low toxicity to mammals at operational doses.…”

Quantitative Trait Loci Mapping of Genome Regions Controlling Permethrin Resistance in the Mosquito Aedes aegypti

“…Cuban and Venezuelan populations of Ae. aegypti have been well characterized for target-site insensitivity (Bisset et al 2006) and various forms of metabolic resistance (Rodriguez et al 2001(Rodriguez et al , 2002(Rodriguez et al , 2005.…”

Aedes aegypti (Díptera-Culicidae) Susceptibility to Temephos in Ciudad del Este, Alto Paraná, Paraguay

“…Así, la aplicación de estos compuestos constituye una poderosa fuerza evolutiva, al permitir la sobrevivencia de aquellos individuos que poseen características fenotípicas de resistencia y éstos heredan esa capacidad a sus descendientes. Por tal motivo, se ha afirmado que el uso correcto de un plaguicida efectivo sobre una población susceptible produce cambios genéticos y fenotípicos que se traducen tarde o temprano en la falta de control de los insectos (21). De este modo, la detección temprana de resistencia de larvas y adultos de Ae.…”