attached
Dengue is a serious arboviral disease in Sri Lanka with an increasing number of
dengue fever cases reporting every year. The control of primary vector Aedes
aegypti solely depends upon the source reduction for breeding and the application
of insecticides to the vector populations. However, increase of reported number of
cases suggests the inefficiency of current control strategies and possibility of
emerging resistance to currently used insecticides. Early detection of kdr mutations
which confer resistance to pyrethroid insecticides is important in management of
resistance in vector populations. Polymerase chain reaction was carried out to detect
the presence of three kdr mutant alleles F1534C, V1016I and V1016G in 207 Ae.
aegypti mosquito samples collected from eight districts (Colombo, Jaffna, Galle,
Kandy, Puttalum, Trincomalee, Hambanthota and Batticaloa) in Sri Lanka. The data
revealed the presence of F1534C mutant allele in Sri Lankan Ae. aegypti
populations for the first time. The mutant allele was found to be wide spread in the
island. It was interesting to note that mutant C allele frequency was highest among
mosquito populations in Jaffna district (0.148) closely followed by populations in
Colombo district (0.143). The lowest was recorded in mosquitoes collected from
Kandy district (0.043). However, the present study was not able to record the
presence of V1016I or V1016G mutant alleles in the studied mosquito populations.
The spread of the mutant allele throughout the country poses a threat of higher
resistance development for pyrethroid insecticides. In Sri Lanka pyrethroids are
extensively used for vector control measures as a routine practice and as an
emergency measure in the event of an epidemic situation. Unplanned and the long
term insecticide applications could have led to resistance development thus more
strategic and diverse tools should be applied for the control of the vector.
