| Pyrethroids are popular insecticides that bind to the insect voltage gated sodium
channel and exhibit an insecticidal knockdown effect. Extensive pyrethroid use can cause
mosquitos to develop knockdown resistance (kdr) making it essential to screen mosquitos
for kdr mutations (Dong et al., 2014).
In this study, I sequenced two regions: a) the L45-S5 linker and b) the IIP-IIS6
region, in domain II of the voltage gated sodium channel in local mosquito species O.
flavescens and A. vexans. Kdr mutation, I936V (Hopkins et al., 2010), was found in all 40
A. vexans. 13 O. flavescens had valine and 27 had the native methionine at position 922.
Homology models of wild-type and mutant A. aegypti and D. melanogaster were
created with MODELLER. Docking studies in AutoDock vina showed that the single
mutations, M922V, I936V or double mutation (I936V + M918T) significantly lowered
the mean free binding energies of deltamethrin, permethrin and DDT.
Key Words: pyrethroids, insecticides, knockdown effect, knockdown resistance (kdr) |