| dc.description.abstract | Being a predominantly abundant area for primary vector of dengue, Colombo
Municipal Council (CMC) has often exposed to chemical vector control strategies in
successive periods of outbreaks to control Aedes aegypti density with space spraying
and Indoor Residual Spraying (IRS) using Lambda cyhalothrin as IRS agent. The
present study was conducted to assess the susceptibility of Aedes aegypti in CMC
area towards Lambda cyhalothrin as an aspect of resistance monitoring for
chemicals used in mosquito control in Sri Lanka by National Dengue Control Unit
(NDCU). WHO standard test kits, procedures and 0.03 % (Discriminative dosage),
0.25 % (8 time higher than discriminative dosage) Lambda cyhalothrin impregnated
papers were utilized to conduct susceptibility test on 500 mosquitoes in 2020 and
2022 where each test consisted with five replicates with 20 mosquitoes in each
replicate. In 2020 Aedes aegypti in CMC area were 5% and 44% susceptible for the
discriminative dosage (0.03%) of Lambda cyhalothrin where in 2022 they were
12% and 3% susceptible for repeat tests for the same which indicates very high
resistance. With 0.25% the susceptibility has increased steeply up to 88% which still
indicates the replaced resistant population. A resistant population of Aedes aegypti
for Lambda cyhalothrin which even can tolerate higher dosages has almost
established, where using Lambda cyhalothrin to control Aedes aegypti in CMC area
is no longer productive. Irrational use of insecticide with no shifting between
chemical classes has led to establishment of highly resistant mosquito population
which should be a highly notable fact in vector control programmes in Sri Lanka. | en_US |
