Abstract
Studies on control effect of the permethrin-impregnated mosquito net against Anopheles farauti, the malaria vector species in the Western Pacific countries were carried out in Solomon Islands in 1985,using the experimental hut attached with the exit window traps. Average mortality rate of the mosquitoes entering the hut was 88.2% for a net treated with 0.5g/m^2 and 84.0% for a net treated with 0.2g/m^2 of permethrin. Mortality rate when the mosquito net was hung with a gap at the bottom was slightly higher than when the net was completely closed, showing 90.2% and 85.1%, respectively. Sixty-nine point nine percent and 71.9% of all mosquitoes that entered the 0.5g/m^2-net hut and the 0.2g/m^2-net hut, respectively were caught in the exit window traps, and mortality rates after 24hr were 84.1% and 79%. In case of the control (untreated mosquito net), 98.4% of the mosquitoes was collected at the exit window traps. The permethrin-impregnated mosquito net did not show any repellent effect, because there was no reduction in the number of the mosquitoes entering the treated hut compared to the control hut (76.5 females/night in the 0.5g/m^2-net hut, 69.5 females/night in the 0.2g/m^2-net hut and 61 females/night in the control hut). It was found that permethrin has the fumigation effect, showing that the mortality rate of the caged An. maculatus females which were hung 30-40cm apart from the permethrin-impregnated mosquito net was 89.9%, 90.0%, 94.9% and 100% at 1.5hr, 3hr, 6hr and 12hr of exposure, respectively.
