Effects of Sodium Percarbonate and Garlic Extract onIchthyophthirius multifiliisTheronts and Tomocysts: In Vitro Experiments

Abstract

White spot disease, which is caused by infections of Ichthyophthirius multifiliis, has a severe impact on productivity in freshwater aquaculture. These infections were previously treated effectively with malachite green, a compound that is now banned on fish farms due to its carcinogenicity. However, aquaculturists need alternative substances to control the disease. Therefore, comparative laboratory tests (in vitro exposure) were performed to elucidate the effects on the infective theront stage and the tomocyst stage of (1) sodium percarbonate, a compound that releases hydrogen peroxide when dissolved in water and (2) extract of garlic Allium sativum. The efficacy of these compounds was compared with that of malachite green. It was demonstrated that at 12ЊC sodium percarbonate (12.5 mg/L) and garlic extract (62.5 mg/L) killed theronts within 3 and 15 h, respectively. Thus, compared with malachite green (0.1 mg/L), higher concentrations of both sodium percarbonate and garlic extract are needed. The effects of the alternative compounds on the tomocyst stage were less pronounced. As expected, malachite green (0.15 mg/L) killed the tomocysts and prevented the development of tomites. In contrast, sodium percarbonate (12.5 mg/L) did not kill the tomocysts. Garlic extract had no effect in low amounts (30 mg/L), but at high concentrations (117 and 570 mg/L) it killed the tomocysts within 24 h. It is concluded that these alternative substances are less effective than malachite green but may represent a way to reduce infections at fish farms with minimal environmental effects. It is emphasized that tolerance tests with various infected and noninfected fish species should be conducted in order to determine safety levels. Further, as the legality of these substances varies across countries, local regulatory authorities should be consulted before using these substances.

Effect of potassium ferrate(VI) on survival and reproduction of Ichthyophthirius multifiliis tomonts

“…In our study, tomonts were obtained according to the method as described above, but tomont survivals (in the control of the four experiments) were only approximately 90%. The result was close to that of Buchmann et al (2003). This demonstrated that about 10% of the parasites appeared dead or had abnormal reproduction in the incubation.…”

“…These data indicated that tomonts were less susceptible to potassium ferrate(VI) than theronts. Buchmann et al (2003) findings suggested that the tomonts resisted some substances better than the theronts. Combined with the results of Straus and Meinelt (2009) and Meinelt et al (2009), it is shown that peracetic acid (PAA) leads to more toxicity to theronts than tomonts.…”

“…The life cycle of this parasite is direct and consists of three stages: an infective theront, a parasitic trophont, and a reproductive tomont (Nigrelli et al 1976;Noe and Dickerson 1995;Swennes et al 2006). Both the theront and tomont stages are free living in the life cycle of I. multifiliis (Buchmann and Bresciani 2001). Killing the parasite at these stages will stop the reproductive cycle and prevent the spread of the disease (Tucker and Robinson 1990;Schäperclaus 1991).…”

Effects of aqueous extract of Capsicum frutescens (Solanaceae) against the fish ectoparasite Ichthyophthirius multifiliis

“…Formerly, ichthyophthiriasis was treated using malachite green and mixtures of malachite green and formalin by immersion with a good deal of success (Leteux and Meyer 1972;Wahli et al 1993;Dickerson and Dawe 1995;Buchmann et al 2003). However, the use of malachite green for the treatment of disease has been no longer permitted by some government agencies, such as the Food and Drug Administration of the USA, due to its potential carcinogenic and teratogenic properties (Alderman 1985;Srivastava et al 2004).…”

An assessment of the use of drug and non-drug interventions in the treatment ofIchthyophthirius multifiliisFouquet, 1876, a protozoan parasite of freshwater fish

“…This organic (triphenylmethane) dye was favoured for the control of I. multifiliis infections because of its high efficacy against both the free-swimming stages (protomonts and theronts) of the parasite and the feeding parasite stage (trophont) within the fish's epithelium (Wahli et al 1993;Tieman and Goodwin, 2001;Buchmann et al 2003). MG and its derivatives (mainly leucomalachite) also display well-documented ecotoxicological effects including cytotoxicity, carcinogenicity, mutagenicity, induction of chromosomal fractures, teratogenicity and respiratory toxicity (Culp and Beland, 1996;Srivastava et al 2004).…”