Acute Toxicity Of Euphorbia Royleana Boiss (Euphorbiaceae) latex on freshwater catfish, Heteropneustes Fossilis (Siluriformes, Heteropneustidae)

摘要

An acute toxicity test was performed by using a four-day static renewal test to determine the LC50 value of aqueous extract of Euphorbia royleana latex for the freshwater fsh, Heteropneustes fossilis. The LC50 values, their upper and lower confdence limits and slope functions were calculated. The LC50 values for aqueous extract of Euphorbia royleana latex at various exposure periods were 7.758 mg/L for 24 h, 5.847 mg/L for 48 h, 4.474 mg/L for 72 h and 3.090 mg/L for 96 h. The regression coeffcient showed that there was signifcant negative correlation between exposure time and different LC values. Hence, it is concluded that the concentration to produce toxicity of latex of Euphorbia royleana is comparable and close to the concentration to produce toxicity of synthetic organophosphates pesticides for the fsh H. fossilis. Therefore, adequate precautions must be taken when Euphorbia royleana latex is being used near fsh- inhabited areas.