EFFICACY OF HERBAL EXTRACT OF Acorus calamus (VASAMBU) AGAINST Argulus spp., AN ECTOPARASITE OF FISH BY IN VITRO METHOD

Aquaculture is the fastest growing industry worldwide with the annual production of 80 million tonnes. Aquaculture production faces a serious threat due to the emergence of diseases caused due to bacteria, virus fungus and parasites.  Argulus spp (Fish louse) is the most common and predominant crustacean parasite which cause serious parasitic disease and also considered as a  potent carrier of viruses and bacteria. Consequently, a wide range of antimicrobials including  antibiotics, chemicals  and pesticides are used to control the disease in aquaculture, which leads to emergence of antimicrobial resistance and pollution to  the environment. Hence,  herbal based drugs are gaining popularity as they are safe alternatives to antibiotics and chemicals. In this study, the herbal extracts of Acorus calamus (Vasambu) was tested for its efficacy against Argulus spp infecting fish.

Treatment for the ectoparasitic disease caused due to Argulus spp (Figure.1)  in freshwater fish include use of  potassium permanganate (KMnO₄), salt, formalin and pesticides. Some of  these compounds possibly leave toxic residues in fish flesh and in the environment which are eventually harmful to consumers. Hence, there is a need for the use of compounds that are safe and effective against Argulus parasite and recently herbal based medicines are widely used to cure the diseases. Acorus calamus (Figure.2) is a herb that has been reported to be popular and effective in controlling the ectoparasites and internal parasites  in animals. The present study was conducted to assess the effectivenes of   A.calamus against   Argulus spp. by in vitro method.  A. calamus were collected, dried, ground and soaked in distilled water for 3 days at room temperature. The filtered aqueous extract was used to assess the lethal concentration (LC₅₀) of the extract in the adults and nauplii of Argulus spp at concentrations ranging from 0.1  ppm to 10 ppm.

The antiparasitic activity of the extract was studied in vitro (Figure.3)  against nauplii and adults of Argulus spp at varying concentrations 0.1 ppm, 0.20 ppm, 0.30 ppm upto 10 ppm. The effective concentration that resulted in 100% mortality in nauplii and adults of Argulus spp were 0.3ppm and 5ppm respectively.The results of this study showed that  the aqueous extracts of Acorus calamus can be used as an alternate and safe drug to control Argulus spp  an important ectoparasite of fish.