Susceptibility tests for pyrethroid insecticides

The susceptibility of Sri Lankan Ae. aegypti to the insecticides permethrin and deltamethrin was evaluated using the standard WHO protocols [19]. Insecticide papers were purchased from WHO affiliated Universiti Sains Malaysia. From each location, one- to three-day-old non-blood-fed females, maintained on a 10% w/v sucrose solution, were used. An experiment consisted of four replicates of 25 mosquitoes with one control. Test mosquitoes were exposed to 0.05% deltamethrin or 0.75% permethrin impregnated papers for 1 h in the exposure tubes. They were then transferred to holding tubes and provided with a 10% w/v sucrose solution. After 24 h, surviving mosquitoes (resistant) and dead mosquitoes that were incapable of movement (susceptible) were counted.