Abstract
The usage of insecticide rendered the successful vector control program with the high usage of the pyrethroid. However, the intensive and extensive use of pyrethroid, causing resistance in Aedesaegypti and hampered the control program. Knockdown resistance (kdr) resulting from the Voltage-Gated Sodium Channel (VGSC) is one of the mechanisms of resistance in pyrethroid group insecticide. Investigating the phenotypic status of Ae.aegypti mosquitoes is a lead in knowing the current resistance status and as an indicator of the genotypic resistance. In this study, we investigate the resistance in phenotypic and genotypic of Ae.aegypti with a new kdr mutation point A1007G was detected. Using the adult bioassay, we tested the phenotypic resistance from the Selangor state against 0.75% permethrin, 0.05% deltamethrin with and without the addition of PBO synergist. Permethrin-resistant and deltamethrin-resistant, including susceptible samples, were subjected to genotyping analysis on mutation point in domain II and domain III of Voltage-Gated Sodium Channel (VGSC). Adult bioassay revealed that the Ae.aegypti was highly resistance toward 0.75% permethrin and 0.05% deltamethrin. The bioassay with the presence of PBO synergist showed an increment of mortality rate, but Ae.aegypti status is still resistance towards both insecticides. Genotyping result showed that three common kdr mutations (S989P, V1016G, and F1534C) have existed in the Ae.aegypti population. A new novel mutation on A1007G was also detected in this population, which is the first time reported. This study has brought a piece of information on the current resistance status in Ae.aegypti in Malaysia. The detection of new mutation point of A1007G has added the knowledge on the resistance in mosquitoes. Thus, this study will aid with the decision making in the usage of insecticides in the vector control program; before this invaluable insecticide rendered ineffective in killing mosquitoes.
Highlights
Dengue is the most important arboviral infections of humans transmitted by Aedes mosquitoes[1]
Pyrethroids function as neurotoxins that target voltage-gated sodium channels (VGSC) and interfere electronic signalling in the nervous system, which results in paralysis and death of the mosquito, an effect often referred to as “knockdown”[12,13]
We investigated the susceptibility of Ae. aegypti on the pyrethroid resistance and examined the kdr mutations in this mosquito species at dengue-endemic areas in Selangor, Malaysia
Summary
Dengue is the most important arboviral infections of humans transmitted by Aedes mosquitoes[1]. The heavy reliance on using residual insecticides such as through intensive and prolonged use have caused insecticide resistance in Aedes mosquitoes, and reduce the effectiveness of adulticide-based control programs around the world, including M alaysia[7,8,9]. The intense usage of these insecticides has been reported to cause insecticide resistance of Ae. aegypti populations in Malaysia. Kdr is the most well-studied target-site pyrethroid resistance mechanisms in insects, including disease vectors such as against Ae. aegypti mosquitoes[15] and a good predictor of the efficacy of pyrethroids is through genotyping of kdr mutant alleles[16]
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