Estandarización de dosis diagnósticas de sinergistas y su validación en la caracterización de los mecanismos de resistencia a insecticidas en Aedes aegypti (Linnaeus, 1762) en los municipios de Villavicencio, Ibagué y Yumbo

Abstract

In Colombia, Aedes aegypti control and prevention programs are based on the application of pyrethroid and organophosphorus insecticides, in cases of an outbreak, in order to cut the transmission chain, but the intensive and extensive use of these compounds has created a pressure of selection, favoring the development and evolution of resistance in several populations of the country. In this sense, synergists in insecticide susceptibility tests, works as a tool for evaluation and determination of the different resistance mechanisms present in several vector species such as Ae. aegypti (PAHO, 2017). This is why the adjustment and validation of diagnostic doses to existing protocols are necessary. The standardization of the diagnostic doses of PBO and DEF, were made following the guidelines of the CDC (2012), with females of the susceptible strain Ae. aegypti "Rockefeller‟, with 70 ppm and 20 minutes being the diagnostic dose for the two synergists. Subsequently, the effect of prior exposure to PBO with Deltamethrin and DEF with deltamethrin and Pyrimiphos-methyl was evaluated. All wild populations were resistant to insecticide deltamethrin and susceptible to pyrimiphos-methyl, with the exception of the Ibagué strain. Previous exposure with synergists increased mortality but only showed significant differences in the DEF + Deltamethrin combination, however, none of the treatments allowed complete restoration of susceptibility. The biochemical tests exhibited an altered and highly altered activity in the OFM in all populations with the exception of Villavicencio - comune 4, while esterases showed a variable altered activity in all populations. Finally, these results show that some individuals in the mosquito populations evaluated do not have enzymatic resistance mechanisms but may be more associated with white site resistance. Additionally, this methodology provides an indispensable input for the initial characterization of insecticide resistance without the need for sophisticated equipment and specialized training of laboratory personnel, in order to contribute to chemical control decision making by the Ministry of Health.