Abstract
Background: Characterization of the insecticide resistance mechanism imparts the society with the information on the evolutionary process involved in the adaptation of Aedes aegypti mosquito to environmental changes. Investigating the phenotypic status of the target mosquitoes, their resistance level as well as elucidating the genotypic profile provides information about the involvement of insecticide resistance mechanism, in terms of portraying the evolution of resistance in the field, to eventually managing vector control programmes. In this current study, we investigated the quantification responses for the phenotypic and genotypic resistance of Ae. aegypti population from different states in Malaysia. Methods: We tested insecticide susceptibility status of adult Ae. aegypti from populations of States of Penang, Selangor and Kelantan (Peninsular Malaysia) against 0.25% permethrin and 0.25% pirimiphos-methyl through WHO bioassay kit. Permethrin-resistant and permethrin susceptible samples were then genotyped for domains II and III in the voltage gated sodium channel (vgsc) gene using allele specific PCR (AS-PCR) for the presence of diagnostic single nucleotide mutations. AS-PCR results were then validated in sequencing these two domains to identify any possible additional point mutations. Results: Adult WHO bioassay revealed that populations of Ae. aegypti from these three states were highly resistant towards 0.25% permethrin and 0.25% pirimiphos-methyl. Genotyping results showed that three knockdown (kdr) mutations (i.e. S989P, V1016G and F1534C) were associated with pyrethroid resistance in these populations. We also report for the first time the presence of the A1007G mutation in Malaysian populations of Ae. aegypti.Conclusions: This study brings an insight on the occurrence and association of point mutations with insecticide resistance in Malaysian populations of Ae. aegypti. The results reveal the widespread of several kdr mutations in the field with the consequence to compromise the use of pyrethroid insecticides in vector control programmes. Knowledge on the distribution of target site resistance throughout Malaysia is vital to ensure the success of the insecticide-based vector control programme.
Point mutations in the voltage-gated sodium channel gene associated with pyrethroid resistance in Iranian populations of the European red mite Panonychus ulmi
