Abstract
BackgroundDengue is a serious arboviral disease in Sri Lanka with a large number of dengue fever (DF) cases every year. Control of the primary vector Aedes aegypti depends upon larval habitat source reduction and insecticide application. However, increases in the number of reported cases suggest the inefficiency of current control strategies and the possibility of resistance to currently used insecticides. Early detection of mutations in the voltage-gated sodium channel (vgsc) gene that confer knockdown resistance (kdr) to pyrethroid insecticides is important in resistance management in vector populations.ResultsResistance to pyrethroid insecticides was detected in the three populations studied. Polymerase chain reaction was used to detect the presence of two kdr mutations F1534C and V1016G. During this process a S989P mutation was also detected in pyrethroid-resistant Ae. aegypti populations. These mutations were found to be widespread and frequent in the collections studied.ConclusionsTo our knowledge, this study reveals for the first time the presence of V1016G and S989P mutant alleles in the vgsc of Sri Lankan Ae. aegypti populations. The spread of the mutant alleles throughout the country poses a threat of increased resistance to pyrethroids. Long-term insecticide applications and indiscriminate use of pyrethroids has led to the evolution of resistance. More strategic and diverse strategies, including novel insecticides with new modes of action and community participation, should be engaged for Ae. aegypti control.
Highlights
Dengue is a serious arboviral disease in Sri Lanka with a large number of dengue fever (DF) cases every year
This study reports the presence of V1016G and S989P mutations in Sri Lanka for the first time
Thermal cyclic conditions were as: initial denaturation at 94 °C for 2 min, followed by 35 cycles at 94 °C for 30 s, 55 °C for 30 s and 72 °C for 30 s, followed by a final extension at 72 °C for 2 min. Results for both F1534C and V1016G were visualized by agarose gel electrophoresis
Summary
Dengue is a serious arboviral disease in Sri Lanka with a large number of dengue fever (DF) cases every year. Detection of mutations in the voltage-gated sodium channel (vgsc) gene that confer knockdown resistance (kdr) to pyrethroid insecticides is important in resistance management in vector populations. In Sri Lanka, pyrethroid insecticides are most extensively utilized as adulticides by both government authorities and the private sector [3] These insecticides act quickly as neurotoxins by binding to the gate of the voltage-gated sodium channel (vgsc), blocking the gate in an open position and thereby preventing development of an electric potential across the membrane. This results in rapid paralysis and death of the mosquito and is often referred to as “knockdown” [4]. Mutations G923V, L982W, Fernando et al Parasites & Vectors (2018) 11:526
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