Watchariya Purivirojkul, Surapol Visetson, Nontawith Areechon, and Sunetharee Phakphong

pp. 431 - 437

Abstract

Study on the efficiency of Citronella grass (Cymbopogon winterianus Jowitt) extracts to control
Zoothamnium sp. was conducted in the laboratory at Kasetsart University. Comparison between two methods
of extractor, water distillation and soxhlet extractor, revealed that soxhlet extractor was about 225 times
more efficient than the water distillation, based on the concentration that could give 100% mortality of
Zoothamnium sp. in 24 hours (0.008 g/l from soxhlet extractor and 1.8 g/l from water distillation). The LC₅₀
of PL15 shrimp in 24 hours of this extract from water distillation was 21.05 g/l while from soxhlet extractor
was 1.88 g/l. Those concentrations, 0.008 g/l from soxhlet extractor and 1.8 g/l from water distillation did not
harmful to the PL15 shrimp measured by dissolved oxygen and pH of water.