Abstract
Persistence of permethrin incorporated in polyethylene net during manufacture of thread was examined after practical use. Regeneration process of efficacy of the used net against Aedes aegypti was also studied. When the net was hung down at openings of houses to control dengue vector mosquitoes in Vietnam, permethrin remained 79% and 58% of the initial content in the nets used inside and outside a house after 7 months, respectively. When an unused net was washed with acetone to remove the active ingredient from the surface of thread, diffusion of the active ingredient from the inside of thread to the surface was accelerated by keeping the net at 60 to 70℃.
