Abstract
BackgroundThere has been no comprehensive study on biochemical characterization of insecticide resistance mechanisms in field populations of Malaysian Culex quinquefasciatus. To fill this void in the literature, a nationwide investigation was performed to quantify the enzyme activities, thereby attempting to characterize the potential resistance mechanisms in Cx. quinquefasciatus in residential areas in Malaysia.Methodology/Principal Findings Culex quinquefasciatus from 14 residential areas across 13 states and one federal territory were subjected to esterases, mixed function oxidases, glutathione-S-transferase and insensitive acetylcholinesterase assays. Enzyme assays revealed that α-esterases and β-esterases were elevated in 13 populations and 12 populations, respectively. Nine populations demonstrated elevated levels of mixed function oxidases and glutathione-S-transferase. Acetylcholinesterase was insensitive to propoxur in all 14 populations. Activity of α-esterases associated with malathion resistance was found in the present study. In addition, an association between the activity of α-esterases and β-esterases was also demonstrated.Conclusions/SignificanceThe present study has characterized the potential biochemical mechanisms in contributing towards insecticide resistance in Cx. quinquefasciatus field populations in Malaysia. Identification of mechanisms underlying the insecticide resistance will be beneficial in developing effective mosquito control programs in Malaysia.
Highlights
Insecticide resistance mechanisms have been the subject of research interest among researchers from different parts of the world, including Malaysia
As far as insecticide resistance mechanisms are concerned in Malaysia, a considerable amount of research indicated that Malaysian mosquitoes have demonstrated variable biochemical mechanisms in resistance to various insecticide classes [11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]
Mosquito Strains Given that there is no specific Culex control program in Malaysia, the study sites were selected on the basis of the incidence of dengue infestations and fogging activities, as intense fogging would inadvertently contaminate the breeding ground and exert selective pressure on Cx quinquefasciatus
Summary
Insecticide resistance mechanisms have been the subject of research interest among researchers from different parts of the world, including Malaysia. It has been proven that increased levels of mixed function oxidases contribute resistance to four major insecticide classes (i.e., organochlorines, carbamates, organophosphates and pyrethroids) [1,2,3]. There has been no comprehensive study on biochemical characterization of insecticide resistance mechanisms in field populations of Malaysian Culex quinquefasciatus. To fill this void in the literature, a nationwide investigation was performed to quantify the enzyme activities, thereby attempting to characterize the potential resistance mechanisms in Cx. quinquefasciatus in residential areas in Malaysia
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