The influence of smoke density on knockdown efficacy of mosquito coil against adults of Culex pipiens pallens

Abstract

When the smoke particles of mosquito coil containing dl, d-T80-allethrin as an active ingredient were observed using the scanning microscope, the diameter of the particles trapped at 3 and 30cm above the burning point of the coil were less than 0.2μm and 0.4 to 1.0μm, respectively. From the observation of the particles using X-ray microanalyzer, where the active ingredient was permethrin, it was revealed that the active ingredient existed on or in the particles. Therefore, it can be considered that the smoke particles played an important role to distribute the active ingredient in air. On the other hand, the knockdown efficacy of the coil containing allethrin against Culex mosquitoes decreased with increase of the smoke density. Since the existence rate of allethrin on the larger smoke particles became larger with the smoke density, the smoke of the coil might be deterrent factor in reducing the knockdown efficacy of the coil against the mosquitoes.