Susceptibility Status and Resistance Mechanisms in Permethrin-Selected, Laboratory Susceptible and Field-Collected Aedes aegypti from Malaysia

Abstract

This study is intended to provide a comprehensive characterization of the resistance mechanisms in the permethrin-selected (IMR-PSS) and laboratory susceptible (IMR-LS) Aedes aegypti strain from Malaysia. Both IMR-PSS and IMR-LS provide a standard model for use in assessing the pyrethroid resistance in field-collected strains collected from three dengue hotspots: the Taman Seri Bayu (TSB), the Flat Camar (FC), and the Taman Dahlia (TD). Two established methods for determining the resistance mechanisms of the pyrethroid are the quantification of detoxification enzymes via enzyme microassay and the nucleotide sequencing of the domain 2 region from segment 1 to 6 via classical polymerase chain reaction (PCR) amplification—were employed. Enzyme activities in IMR-LS served as the resistance threshold reference, providing a significant standard for comparison with IMR-PSS and other field-collected strains. The amino acids in the domain 2 region of voltage-gated sodium channel (Vgsc) of IMR-LS were served as the reference for detection of any changes of the knockdown resistance (kdr) alleles in IMR-PSS and field-collected strains. Studies clearly indicated that the IMR-LS was highly susceptible to insecticides, whilst the IMR-PSS was highly resistant to pyrethroids and conferred with two resistance mechanisms: the elevated oxidase enzyme activity and the altered target-site mutations. Mutations of V1023G alone, and the combination mutations of V1023G with S996P in IMR-PSS, as well as the in field-collected Aedes aegypti strain, indicate the spread of the (kdr) gene in Aedes aegypti, particularly in dengue-endemic areas in Malaysia.

Molecular Insight into the Knockdown Resistance (kdr) in the Voltage Gated Sodium Channel (vgsc) Gene of the Main Dengue Vector, Aedes aegypti (Diptera: Culicidae) and the Discovery of Novel Regional Specific Point Mutation A1007G in Malaysia.

“…Our results contradicted a study conducted in 2011 and also previous studies [20,21,22] revealing that Ae. aegypti populations from Penang were at that time fully susceptible towards pirimiphosmethyl and malathion [50].…”

“…Results of the susceptibility bioassay revealed that Ae. aegypti populations from Penang, Kelantan and Selangor exhibit high resistance towards the insecticides from the class of pyrethroid (Type I: permethrin) and organophosphate (pirimiphos-methyl) with the percentage mortality after 24-hour exposure less than 90% confirming these populations are resistant as shown recently [20,21,22].…”

“…The nonsynonymous mutations S989P, V1016G and F1534C correspond to a substitution of amino acid serine to proline, valine to glycine and phenylalanine to cysteine, respectively, within domains II and III. These mutations were previously shown to be widely distributed across Malaysia [20,21,22]. Other studies have reported that these mutations are widely established across Southeast Asia, including Indonesia, Thailand, Singapore, Myanmar and Vietnam [23,24,25,26,27].…”

Susceptibility of three Colombian Aedes aegypti Linnaeus (Diptera: Culicidae) populations to a Lysinibacillus sphaericus formulation

“…A study conducted by Fonseca‐González et al () suggested that pyrethroids, organophosphates and DDT used in public health have led to the development of resistance in A. aegypti populations, with variations in the resistance levels, probably depending on the specific selection pressures in each location. Considering the current status of insecticide resistance in A. aegypti , in addition to the evidence of continuous gene flow among A. aegypti populations (Ayres, Melo‐santos, Solé‐Cava, & Furtado, ) and the relatively rapid changes in enzyme levels associated with insecticide resistance (Rasli et al, ), biological control through a L. sphaericus formulation is a suitable alternative.…”

Characterization of Sodium Channel Mutations in the Dengue Vector Mosquitoes Aedes aegypti and Aedes albopictus within the Context of Ongoing Wolbachia Releases in Kuala Lumpur, Malaysia

“…The results are very different from similar studies of Ae. aegypti from Kedah and Johor states (the northern and southern regions of Malaysia) [47] as well as Yogyakarta [14], in which mutations at 1016 and 989 were common, but 1534 was rare. Within southeast Asia and the Indo-Pacific, the F1534C mutation in Ae.…”