Affiliations: *Malaria Center I, Phraphutthabat, Department of Communicable
**Division of Medical Entomology, Department of Medical Sciences
Source: Communicable Disease Journal 1996; 22(2): 101-106
Language: Thai with English abstract
A comparative study to determine efficacy of permethrin kept at various durations was carried out. WHO standard bioassay test was employed using 3-minute exposure period. Mosquito vectors namely An. dirus, An minimus and An. maculatus reared in insectary and collected from field condition were used in this study. Results revealed that residual effect of permethrin one - year kept at the dosage of 0.3gm/m2 lasted at least 11 months, with mosquito mortality rates higher than 90% The residual effect of the two - year kept permethrin at the same dosage lasted approximately 4-5 months with mortality rates between 50-60% The result suggested that shelf life of this chemical is short. Shelf life of this chemical therefore should be taken into consideration for procurement and distribution.