First detection of a allele V1016G conferring a high level of insecticide resistance in collected from Europe (Italy) and Asia (Vietnam), 2016: a new emerging threat to controlling arboviral diseases.

Introduction (Skuse) is an important vector of arboviral diseases, including dengue, chikungunya and Zika virus disease. Monitoring insecticide resistance and mechanisms by which the mosquito develops resistance is crucial to minimise disease transmission.AimTo determine insecticide resistance status and mechanisms in from different geographical regions.MethodsWe sampled 33 populations of from Asia, Europe and South America, and tested these for susceptibility to permethrin, a pyrethroid insecticide. In resistant populations, the target site for pyrethroids, a voltage-sensitive sodium channel () was genotyped. Three resistant sub-strains, each harbouring a resistance allele homozygously, were established and susceptibilities to three different pyrethroids (with and without a cytochrome P450 inhibitor) were assayed.ResultsMost populations of tested were highly susceptible to permethrin but a few from Italy and Vietnam (4/33), exhibited high-level resistance. Genotyping studies detected a knockdown resistance () allele V1016G in for the first time in . Two previously reported alleles, F1534C and F1534S, were also detected. The bioassays indicated that the strain homozygous for the V1016G allele showed much greater levels of pyrethroid resistance than other strains harbouring F1534C or F1534S.ConclusionThe V1016G allele was detected in bothAsian and Italian populations, thus a spread of this allele beyond Italy in Europe cannot be ruled out. This study emphasises the necessity to frequently and regularly monitor the V1016G allele in , particularly where this mosquito species is the main vector of arboviruses.