First detection of V410L kdr mutation in Aedes aegypti populations of Argentina and its correlation with the toxicological evidence

BACKGROUND Aedes aegypti (L.) is the main vector of dengue, yellow fever, Zika and chikungunya viruses in many parts of the world impacting millions of people worldwide each year. Insecticide-based interventions have been effective in controlling Aedes mosquito populations for several years, but in recent times, resistance to these compounds has developed, posing a global threat to the control of this mosquito. METHODS Ovitraps were used to collect A. aegypti eggs in the cities of Tartagal and San Ramón de la Nueva Orán (Salta), Puerto Iguazú (Misiones) and Clorinda (Formosa). WHO impregnated papers with the discriminating concentration (DC) of permethrin, 5X, 10X and pirimiphos methyl were used for the toxicological bioassays. We also genotyped each sample for the three kdr single nucleotide polymorphisms (SNP): V410L, V1016I and F1534C in individual TaqMan qPCR reactions. RESULTS All investigated A. aegypti populations were highly resistant to permethrin, as the mortality percentage with the permethrin 10XDC remained below 98%. However, all populations were 100% susceptible to pirimiphos-methyl. Kdr genotyping demonstrated the presence of the V410L mutation for the first time in Argentina in all the populations studied. A prevalence of the triple mutant genotype (LL + II + CC) was observed in the northeastern cities of Clorinda (83.3%) and Puerto Iguazú (55.6%). CONCLUSIONS This study demonstrates for the first time the presence and intensity of resistance to permethrin in different populations from Argentina, and correlates the observed phenotype with the presence of kdr mutations (genotype).