Objective
To evaluate relationship between ¦Á-cypermethrin residues in Interceptor? nets by using HPTLC methods and mortality percentage in standard WHO's method ¡°cone test?after repeated washings.
Methods
Interceptor? containing ¦Á-cypermethrin was provided by BASF Company. The washing procedure and bioassay tests were carried out according to the WHO-recommended methods. Malaria vector, An. stephensi was exposed to impregnated bed net for three minutes and then mortality measured after 24 hour recovery period. Chemical analysis was carried out in chemical laboratory by using high performance thin layer chromatography method.
Results
Result of cone bioassay method showed that washing reduced the efficacy of Interceptor? bed net from 100 % in unwashed nets to 15 % at 20 washes. After 20 washes, nets contain (61.2¡À2.8) mg/m2 resulting 15 % mortality in cone test. Killing activity was reduced when nets were washed.
Conclusions
Results will provide an essential clue for monitoring and evaluation of bioefficacy of any long lasting impregnated bed net for quality control. Findings of this study will be useful for WHO, local investigators and people who wish to use pyrethroidimpregnated bed nets for malaria vector control.
