Abstract
BackgroundDengue vector control programmes are facing operational challenges due to resistance against commonly used insecticides throughout the endemic countries. Recently, there has been appreciable increase in the dengue cases in India, however, no recent data are available on susceptible status of dengue vectors. We have studied the susceptibility level of St. albopicta to commonly used insecticides in India. Adult mosquitoes were tested for the presence of dengue virus.MethodsSt. albopicta larval bioassays were carried out to determine the lethal concentrations (LC10, LC50 and LC99) and the resistance ratios (RR10, RR50 and RR99) for temephos. Susceptibility to 4% DDT, 0.05% deltamethrin and 5% malathion was assessed following standard procedure. Knock-down times (KDT10, KDT50 and KDT99) were estimated and knock-down resistance ratios (KRR10, KRR50 and KRR99) were calculated. VectorTest™ dengue antigen assay was used to detect the dengue virus in the field collected mosquitoes.ResultsIn larval bioassays, the RR ranged from 1.4 (for RR99) to 1.7 (for RR50), which suggested that the tested St. albopicta were susceptible to temephos. There was no deviation among the lethal concentration data from linearity (r2 = 0.61). Adult St. albopicta mosquitoes were resistant to DDT, while fully susceptible to deltamethrin and malathion. The knock-down values (KDT10, KDT50 and KDT99) obtained for DDT displayed straight line in log-dose-probit analysis and follow linear regression model. The KRR99 for DDT was 4.9, which indicated a 4.9 folds increase in knock-down resistance to DDT. However, for malathion and deltamethrin, the KRR99 values were 1.6 and 1.5 respectively suggesting that mosquitoes were knock-down sensitive. None of the mosquito pool was dengue virus positive.ConclusionSt. albopicta showed resistance to DDT and reduced sensitivity to deltamethrin and malathion. This data on insecticide resistance could help public health authorities in India to design more effective vector control measures. More dengue vector specimens need to be scanned to identify the potential dengue vector.
Highlights
Dengue vector control programmes are facing operational challenges due to resistance against commonly used insecticides throughout the endemic countries
The baseline LC10, LC50 and LC99 value obtained in the laboratory strain (LS) larval bioassay exhibited a straight-line relationship between the insecticide log dose and probit mortality (χ2 = 1.28; p = 0.6)
The LC10, LC50 and LC99 values observed in the wild strain (WS) displayed in straight line probit relationship (χ2 = 2.34; p = 0.3) and the data did not deviate from linearity (r2 = 0.61)
Summary
Dengue vector control programmes are facing operational challenges due to resistance against commonly used insecticides throughout the endemic countries. Many recent studies have demonstrated either the development of resistance or decrease in the susceptibility to synthetic insecticides in St. albopicta and St. aegypti mosquitoes in many endemic countries [10,11,12], such data, especially on St. albopicta is very limited in India and only a few systematic studies have been carried out to establish its susceptibility status [13,14]. In India, recently dengue has dramatically spread to many areas where it was not reported earlier, owing to which there is urgent need to determine the susceptibility status of the prevalent dengue vector to the commonly used insecticides in the control programme. Keeping in view the fact that in 2013, the region has reported around 5,000 confirmed dengue cases, the present study was undertaken to establish the insecticide resistance status against the commonly used insectides and to identify the prevalent dengue vector in order to implement effective and sustainable arbovirus vector control measures in the region
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
