Identificación molecular de la resistencia al insecticida Lambda-Cialotrina en el mosquito Aedes Aegypti de Cúcuta Norte de Santander, Colombia.

Abstract

Diseases caused by arboviruses, such as Dengue, Chikungunya, and Zika, constitute a problem for public health at on a state and national level. Currently in Colombia, as of the thirtieth epidemiological week, the SIVIGILA has reported 402 cases of Dengue, while as of the sixteenth week there have been 329 new cases of Zika and 180 cases of Chikungunya. To control insect vectors, there continues to be a consistent use of biological control, environmental manipulation, and biological and chemical insecticides. The principle strategy for the control of Ae. aegypti is the use of chemical insecticides, specifically the use of pyrethroids. Nevertheless, insect resistance to this chemical intervention has been reported. This resistance on a world scale is largely associated with mutations to the sodium channel gene (knockdown resistance (kdr)). This work aims to characterize the state of resistance to lamda-cyhalothrin and identify mutations to the coding region for sodium channels in populations of Ae. aegypti. residing in northern Cúcuta de Santander. For the study, immature Ae. aegypti were collected from the towns of Toledo Plata, Santa Teresita, Circunvalación, and Tucunaré in Cúcuta. Under laboratory conditions, the F0 adult generations and F1 larva generations were obtained. Larvae were selected in between their third and fourth developmental stage and were exposed to six concentrations of insecticides (98% lamda-cyhalothrin). Larval mortality was calculated 24 hours after exposure using methodology from World Health Organization. In adult forms DNA extraction was performed to identify sodium channel mutations using allele specific polymerase chain reaction (AS-PCR). Resistance to lamda-cyhalothrin and three sodium channel mutations were identified in the analyzed populations. The presence of allele 1558C was identified in 100% of samples suggesting that this mutation confers resistance to insecticides other than lamda-cyhalothrin. Additionally, there was a positive association to resistance to lamda-cyhalothrin in 50% of samples with V419L and V10161 mutations. We conclude that the indiscriminate use of insecticide in the region has allowed for the development of insecticide resistance that will persist over time. Based on these results, we recommend the discontinuation of insecticide use for a large period to increase insecticide susceptibility in populations.