JP5553337B2 - Marine fish white spot disease preventive and therapeutic agent - Google Patents

Description

  The present invention relates to a prophylactic / therapeutic agent for white spot disease caused by Cryptocaryon irritans parasitic on marine fish.

  White spot disease is one of the infectious diseases of marine fish such as flounder and Thailand. When white spot disease occurs in the farm, mass death occurs and the damage is enormous.

  Although the cause of marine fish white spot disease is a ciliate as well as the causative parasite of freshwater fish white spot disease, it is a parasite called Cryptocaryon irritans belonging to a completely different taxon. The life history of Cryptocaryron irritans is as follows. That is, when the seron (infected larva) drifting in the water touches the body surface, wings, and wings of the fish body, it enters the cell layer of the epithelium of these wings and body surface, and becomes a trohont (infectious worm body) grow up. Grown trophon leaves the fish, becomes a protomont and sinks to the bottom of the water. When it sinks to the bottom of the water for several hours, it becomes a cystized tomont. In this tomont, larvae are formed by repeating cell division and released into the water as a seront. The number of days until the fish grows and leaves, and the number of days until the seront is released from the cyst depends on the temperature, but at a water temperature of 25 degrees, it is about 3 to 4 days and 4 to 10 days, respectively. .

  The characteristic of white spot disease is that the fish body is not killed when the insect body invades into the fish body, but the fish body is damaged when the insect body grows and leaves the fish body. To die based on injury.

  Since Cryptocarriton irritans, which is the cause of white spot disease, cannot be grown in vitro like many fish parasites, the development of preventive and therapeutic agents is extremely difficult.

  As anti-fish white spot disease preventive and therapeutic agents, lysozyme chloride, lactoferrin, medium chain fatty acids and the like are known (Non-Patent Documents 1, 2, and 3), but the former two do not act directly on the worm body. The effect is thought to be due to the promotion of mucus secretion in fish and the improvement of biological defense ability. In addition, medium chain fatty acids are known to have an insecticidal effect on worms before entering the fish body, but the mechanism of action on worms in the fish body is unknown.

  As a countermeasure against white spot disease, for appreciation fish in a closed environment such as an aquarium, add copper ions, methylene blue, malachite green, etc. to the breeding water for a long period of time, so that insects in the developmental stage outside the fish body can be removed. The technique of killing is used. Fish that are raised in an open environment, such as netting, cannot use the method of adding chemicals to these breeding waters. In addition, these drugs cannot be used for food fish due to food hygiene problems. For edible fish, the movement of ginger to the sea area where the tidal current is fast, the administration of lysozyme chloride as a drug or the addition of medium chain fatty acid (capric acid) to the feed, the effect is There is a need for limited and more effective prophylactic treatments.

Fish Pathology, 30, 4, 289-290 Fish & Shellfish Immunology, 18, 2, 109, 124 Aquaculture, 198, 3-4, 219-228 Disease of Aquatic Organisms, 78, 2, 155-160

  An object of the present invention is to provide an agent for preventing and treating white spot disease, which exhibits an insecticidal effect on Cryptoccharyon irritans parasites that are parasitic on marine fish.

  Therefore, the present inventor examined the in-vitro culture means of Cryptocarriton irritans parasites, and layered agarose gel made of cell culture medium on a cultured cell layer of fish to form a culture medium. The cell layer and agarose gel By adopting a method of inserting a seronto between layers, this parasite was successfully developed (Non-patent Document 4). As a result of various studies using this system, it was found that ionophore antibiotics have an insecticidal effect on worms, and that the effect has an insecticidal effect and a growth inhibitory effect on worms parasitic on fish. . Furthermore, as a result of actually carrying out a Cryptocarriton irritans infection experiment using marine fish, it was confirmed that ionophore antibiotics significantly suppressed death due to white spot disease, and the present invention was completed.

That is, the present invention provides a marine fish white spot disease preventive and therapeutic agent comprising an ionophore antibiotic as an active ingredient.
In addition, the present invention provides a method for preventing and treating marine fish white spot disease, which comprises administering an ionophore antibiotic to marine fish.

  ADVANTAGE OF THE INVENTION According to this invention, it has the insecticidal effect and growth inhibitory effect with respect to the Cryptocaryon irritans parasite which is parasitic on the fish body of marine fish, and can suppress the death number by the white spot disease of marine fish remarkably.

C. Figure 3 shows the effect of sodium salinomycin on the survival rate of irritans trohont. C. Figure 6 shows the effect of monensin sodium on the survival rate of irritans trohont. C. The effect of narasin on the survival rate of irritans trohont is shown. C. Figure 2 shows the effect of Senduramycin sodium on the survival rate of irritans trohont. The survival rate for white spot disease is shown by oral administration of salinomycin sodium (concentration in feed: 200 ppm).

  The active ingredient of the agent for preventing and treating marine fish of the present invention is an ionophore antibiotic. Examples of the ionophore antibiotics include salinomycin, monensin, nalasin, senduramycin, rasaloside, salts thereof, and the like. More preferred is salinomycin or a salt thereof. Here, as a salt, alkali metal salts, such as sodium and potassium, are preferable.

  As will be described later in Examples, the ionophore antibiotic has an insecticidal effect and a growth-inhibiting effect on Cryptocarriton irritans parasites of marine fish, and has an action of preventing death of marine fish due to white spot disease. Therefore, white spot disease of marine fish can be prevented and treated by administering ionophore antibiotics to marine fish.

  The means for administering the ionophore antibiotic is not particularly limited, but oral administration is preferred because it is simple and safe. In order to orally administer the ionophore antibiotic, it is preferable to administer the ionophore antibiotic in a feed (food). The concentration of the ionophore antibiotic in the feed or feed additive is preferably 4 parts by weight or more, more preferably 4 to 500 parts by weight, and particularly preferably 10 to 500 parts by weight. The dose of ionophore antibiotic per 1 kg body weight of marine fish is preferably 0.1 to 50 mg, more preferably 0.25 to 25 mg per day.

  The white spot disease preventive / therapeutic agent of the present invention may be separately administered without being mixed in the feed. Examples of the form include powder, granule, pellet and the like.

  In the case of the above-mentioned feed, feed additive, and other forms, in addition to ionophore antibiotics, for example, calcium carbonate, calcium phosphate, calcium sulfate, flour, starch, dextrin, feed yeast and feed raw material grains They may be mixed with algae and moss and diluted, or added to premixes of vitamins, minerals, etc. or fish feeds containing these premixes. In the case of raw food, additives such as sodium alginate and guar gum may be used at the same time.

  The target marine fish of the white spot disease preventive and therapeutic agent of the present invention is not limited as long as it is all marine true bone fish. Examples include sea bass fish such as yellowtail, hiramasa, mahata, kue, pheasant grouper, cedar, etc.

  The administration timing of the white spot disease preventive / therapeutic agent of the present invention can be administered before Cryptocalyon irritans parasitizes, or can be administered when a symptom of white spot disease is discovered.

  EXAMPLES Next, an Example is given and this invention is demonstrated still in detail.

Example 1
(Method)
According to the description of Non-Patent Document 4, various concentrations of ionophore antibiotics in various concentrations of ionophore antibiotics in an agarose gel of a marine fish white spot insect medium in which a cell culture medium and an agarose gel are overlaid on a fish culture cell layer. Add the Seronto suspension of marine fish white spot worms between the fish cell layer and the agarose gel layer using a micropipette, count the Seronto immediately after insertion, and then add the Seronto The survival rate was calculated by counting the number of

(result)
FIGS. 1 to 4 show changes in the survival rate of Cryptocaryron irritans trofonds in cultures added with various ionophore antibiotics. As is clear from FIGS. 1 to 4, all of salinomycin sodium, monensin sodium, narasin, and senduramycin sodium significantly suppressed the survival rate of trohont.

Example 2
Protomont's flounder (total length approximately 5cm) was fed with a diet (concentration of 200ppm) supplemented with salinomycin sodium and senduramycin sodium, immersed in the Seronto suspension, attacked, and protomonts withdrawn from flounder The diameter of the tomont formed by cystizing the number and the protomont was measured.

  After administration of the drug for 5 days, C.I. Table 1 shows the number of trohonts recovered from Japanese flounder attacked by the irritans seronto and the diameter of the tomont formed by cysting the recovered trohont.

  C. Table 2 shows the number of trohonts recovered from Japanese flounder administered with the drug for 5 days before the irritans attack and 3 days after the attack, and the diameter of the tomont formed by cysting the recovered trohont.

  From the results of Tables 1 and 2, with salinomycin sodium, both the number of insects recovered and the diameter of Tomont were significantly reduced. In Senduramycin sodium, although there was no significant difference, the number of recovered worms decreased, and the diameter of the obtained tomont was significantly reduced. From this, it was confirmed that the ionophore antibiotic has an insecticidal effect and a growth inhibitory effect on the Cryptocaryon irritans parasite that contributes to fish.

Example 3
Shrimp larvae fed with a diet supplemented with salinomycin sodium (200 ppm) for 5 days were challenged with a seronto suspension, and thereafter salinomycin sodium was fed daily and observed as time to death.
As a result, as shown in FIG. 5, in the salinomycin sodium administration group, the time until death due to white spot disease of flounder was clearly suppressed.

Claims (2)

A marine fish white spot disease preventive or therapeutic agent comprising one or more ionophore antibiotics selected from salinomycin, monensin, nalasin, senduramycin and salts thereof as an active ingredient. Dosage form, marine fish white spot disease prevention treatment agent according to claim 1 is administered orally.

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