Effect of twenty Chinese herbal medicines on killing trophonts,cysts and theronts of Ichthyophthirius multifiliis in vitro

The effect of water extracts of twenty Chinese herbal medicines on killling the three-stage parasites(trophonts,cysts,and theronts) of Ichthyophthirius multifiliis was studied in vitro.The results of the experiments were concluded as follows:The aquatic extracts of Areca catecthu and Prunus mume at the concentration of 0.1 g/L could kill the three-stage parasites.And the water extracts of Rheum officinale and Scutellaria baicalensi were able to kill theronts within an hour at the concentration of 0.1 g/L,in addition,then could kill trophonts and cysts at the concentration of 1.0 g/L.These indicated that the aquatic extracts of the Chinese herbal medicines,viz.,A.catecthu,P.mume,R.officinale and S.baicalensi were better than the others on killing the parasite.Meanwhile,the experiments also revealed that the extracts of the thirteen Chinese herbal medicines,Dryopteris setosa,Lindera aggregata,Citrut aurantium,and so on,just had insecticidal role to some extent,when their concentrations reached 10 g/L or 50 g/L or 100 g/L.However,the water extracts of Rehmannia glutinosa,Wolfiporia cocos and Astragalus membranaceus could not kill the parasite even at the concentration of 100 g/L.The results demonstrated that some Chinese herbal medicines really had potential power to control ichthyophthiriasis in aquaculture.Therefore,it′s necessary to look for effective drugs from a lot of Chinese herbal medicines by means of killing the parasite trial.