Acute toxicity of three drugs acting on nymph of Sipunculus nudus

With a view to provide some useful information for the control or kill the harmful micro-organism in the cultivation of Sipunculus nudus,the acute toxicity experiment of trichlorfon,fenpropathin and phoxim-fenvalerate mix on 2～3 cm body length nymph of S.nudus was performed in stilled water at the conditions of water temperature of 29.1～30.7℃,pH 8.0～8.2 and salinity of 29.5.The results indicated that the 24 h LC50,48 h LC50 and SC(safe concentration) of trichlorfon were 1.03,0.67 and 0.09 mg·L-1.The 24 h LC50,48 h LC50 and SC of fenpropathin were 0.70,0.54 and 0.10 mg·L-1`.The 24 h LC50,48 h LC50 and SC of phoxim-fenvalerate mix were 0.72,0.48 and 0.06 mg·L-1.