Experimental treatments with diflubenzuron and deltamethrin of sea bass, Dicentrarchus labrax L., infected with the isopod, Ceratothoa oestroides (2004) (original) (raw)
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Aquaculture, 2019
The haematophagic isopod parasite Ceratothoa oestroides (Risso, 1816) causes significant production losses in the commercial aquaculture of sea bass (Dicentrarchus labrax L. 1758). These are often expressed as reduced fish growth and lower survival rates of sea bass fingerlings < 20 g mass. Deltamethrin is a synthetic pyrethrin with demonstrable positive results in the control of C. oestroides. The aim of this study was to determine its efficacy in the control of C. oestroides in commercial production conditions. The experiment was carried out at a commercial sea bass farm and in two net cages of 16 m diameter stocked with 200,000 sea bass fingerlings of the same origin and weight. After 5 months culture, a deltamethrin treatment was performed in one cage, while the other cage served as a non-treated control. The average sea bass mass during the antiparasitic bath was 19.70 ± 0.47 g and 18.48 ± 0.50 g (mean ± SEM) for the treated and the control cages, respectively. Two months after the treatment, visual examination of the entire population was carried out. The results revealed that the number of C. oestroides in the treated cage was significantly lower (P < .01) compared to those in the control cage. Also, the C. oestroides were smaller in length in the treated group compared to the control cage. No sexually mature females were found in the treated group whereas in the control cage 21.3% of the C. oestroides were sexually mature, containing average 39.7 pulli larvae. The monthly mortality rate during this study was < 0.5%, but mortality in the treated cage, after treatment in June, was lower than in the control cage. The results indicate that the deltamethrin treatment was successful in sea bass infected with C. oestroides. After two months, however, a new generation of immature C. oestroides appeared. These results show that sea bass weighing over 20 g can be reinfected, but the absence of sexually mature females points to the importance of this treatment to reduce the dynamics of C. oestroides population on a farm site. Despite good antiparasitic results, there is a further need to improve fish farming in the Mediterranean through the introduction of changes in husbandry practices with a purpose of prevention of parasitic horizontal transmission.
Therapeutants used for Protozoan Parasitic Diseases in Fishes
Chronicle of Aquatic Science, 2023
Globally, finfish aquaculture is constantly growing in both freshwater and marine environments, and there is clear potential for a significant further growth. When infection intensities in the enclosed aquaculture environment reach high levels, they may then produce disease. The difficulty posed by parasites is further exacerbated by the possibility of parasite transfer from aquaculture operations to wild fish stocks. Veterinarians are responsible for treatment using the prescribed therapeutant on the fish farm and are also involved with the aquaculture operator to ensure that the treated fish or crustaceans are safe for human consumption. The current work describes integrated control techniques, health management and treatment protocols for diseases brought on by protozoan parasites in more detail and promote their usage.
Current practices in the chemotherapeutic control of sea lice infestations in aquaculture: a review
Journal of Fish Diseases, 1993
This review surveys the available literature on the effieaey and eeotoxieology of chemotherapeutic agents for the control of sea lice (Copepoda: Caligidae) infestations in marine aquaculture. To date, treatment for the disease has relied almost exclusively on the use of the organophosphorus pesticides, trichlorfon and dichlorvos. While use of dichlorvos and trichlorfon appears to have little, if any, environmental impact, protracted use in some areas has led to reduced efficacy. Compounds proposed for sea lice control currently under field evaluation include azamethiphos (organophosphate), ivermectin (avermectin), pyrethrum (pyrethrin) and hydrogen peroxide. Although all of these eompounds are effi cacious, at present published information on marine environmental toxicology is scarce and is limited to in vitro toxieity testing. Other compounds that have been considered for sea lice control include formalin, malathion (organophosphate), earbaryl (earbamate), diflubenzuron (insect growth regulator) and natural remedies (i.e. onions and garlic). In general, formaldehyde (aldehyde), malathion and natural compounds show either poor efficacy or unsuitable therapeutic margins. Although earbaryl and diflubenzuron are both efficacious and exhibit suitable therapeutic margins, available data suggests that the compounds, due to undesirable environmental toxieologieal characteristics, would be unsuitable for sea lice control. tf I. Geographic ;iiul laxonomic dislribution of parasitic copcpods and branchiurians recorded in marine fish larming (with iclcrcncc to the genera Argulus, Caligus, Ergasilus, Lepeophtheirus and Pseudocaligus
Diseases of Aquatic Organisms, 1990
The antiparasitic efficacies of 9 benzimidazoles in commercially avalable formulations were tested (water bath treatments) on small pigmented eels Anguilla anguilla, expenmentally infected by 30 to 140 specimens of Pseudodactylogyrus spp. (Monogenea). Exposure time was 24 h and eels were examined 4 to 5 d post treatment. Mebendazole (Vermox; 1 mg 1-') eradicated all parasites, whereas luxabendazole (pure substance) and albendazole (Valbazen) were 100 % effective only at a concentration of 10 mg I-'. Flubendazole (Flubenol), fenbendazole (Panacur) and oxibendazole (Lodltac) (10 mg l-') caused a reduction of the infection level to a larger extent than did triclabendazole (Fasinex) and parbendazole (Helmatac). Thiabendazole (Equizole), even at a concentration as high a s 100 mg l-', was without effect on Pseudodactylogyrus spp.
Diseases of Aquatic Organisms, 2011
Few drugs are approved by the United States Food and Drug Administration for treating parasite infections in minor species such as fish, due in part to the high cost of developing such drugs and to a relatively small market share for drug sponsors. Because in vivo effectiveness trials for antiparasitic drugs are costly, time consuming, and use many animals, a systematic in vitro screening approach to describe parasite motility could help find promising drug candidates. We evaluated the effects of 7 antiparasitics on the activity and survival of the endoparasitic monogenean Acolpenteron ureteroecetes (Dactylogyridae) collected from the posterior kidneys of juvenile largemouth bass Micropterus salmoides (Lacepede, 1802) (Centrarchidae) held in the laboratory. Tests were conducted in 12 well tissue culture plates; each well had 3 parasites, and we tested 3 concentrations and 1 control for each of the 7 antiparasitics. The parasites were observed immediately after adding the drug, at 1 to 3 h, and 17 to 26 h, and video recordings were made. Drug effects were recorded by documenting morbidity (reduced movement, tremors, contracted body, abnormal morphology) and mortality. A. ureteroecetes was strongly affected by the quinoline praziquantel, the imidazothiazide levamisole, and the organophosphates dichlorvos and trichlorfon. The parasites were moderately affected by the macrocyclic lactones ivermectin and emamectin, and generally unaffected by the benzimidazole mebendazole. Our study demonstrates the utility of characterizing in vitro responses with video microscopy to document responses of fish parasites for initial screens of drug effects on a fish monogenean.
Bulletin of The European Association of Fish Pathologists, 2009
Sea bass, Dicentrarchus labrax naturally infected with L. kroyeri were exposed to dosage of trichlorfon for 7 days: 0 (as control), 50 mg kg-1. On days 0, 7, 14, 21, 28 and 35 of the experiment, fish were randomly sampled and weighed, and then parasites on the gills were counted. Comparisons were made to untreated control fish. Sea water temperature and salinity in the pens were measured as 16.0-16.5 oC and 35 ppt, respectively. When the study began, all of the examined fish were infected with L. kroyeri. There were no statistical differences (P > 0.05) in terms of mean number of L. kroyeri within each group, including the control. According to the IRR coefficients, 50 mg dose of trichlorfon reduce the males at 98.3%, females at 97.1% and the total 97.1% when compared to the control group. No mortality was found and adverse drug reactions or palatability problems were not associated with the treatments during the study. Introduction Lernanthropus is the most common genus of paras...
Aquaculture, 2014
Since 2009 infestations of sea lice, Lepeophtheirus salmonis and Caligus elongatus on farmed salmon Salmo salar, in New Brunswick, Canada have been controlled by pesticides applied in bath treatments. Given the potential for effects on non-target organisms, a study was conducted to determine the dispersion from bath treatments of Salmosan® (active ingredient azamethiphos) and AlphaMax® (active ingredient deltamethrin) solutions, either in enclosed net pens or in well boats. The toxicity to Eohaustorius estuarius, Crangon septemspinosa, and Mysis stenolepsis of water samples taken in the dispersing plume was also assessed. A dye, sodium fluorescein, was added to the treatment solutions and a fluorometer was used to track the plume at various times after release of the pesticide solution after treatment. A strong correlation between dye and pesticide concentrations demonstrated the utility of real time dye measurements for following dispersing plumes. In water samples, azamethiphos was measured in greater concentrations in the aqueous phase than in the particulate phase. Deltamethrin, however, was in greater concentrations in the particle phase. The residues of azamethiphos measured after net pen treatments were approximately 3 times than those measured after the well boat treatment. Although 100% of exposed E. estuarius were affected (mortality and paralysis combined) in short term exposures (1 h) to ambient water samples taken in the net pen during treatments with Salmosan®, there was no substantive effect after the treatment solution was released, even when samples were taken directly adjacent to the net pen. Longer exposures (48 h), however, produced toxicity in samples taken up to 850 m from the net pens. Compared with Salmosan® treatments, the plume from AlphaMax® net pen treatments was more toxic with samples producing an EC50 (mortality plus paralysis) to E. estuarius in short term (1 h) exposures up to 350 m from the edge of the net pen.
Diseases of Aquatic Organisms, 2006
A historical control clinical trial was performed to assess the effectiveness of teflubenzuron in controlling sea lice Lepeoptheirus salmonis burdens on farmed Atlantic salmon Salmo salar over time. The study site comprised 9 sea cages, all of which were treated. The teflubenzuron was administered in the feed, at a dosage of 10 mg kg-1 biomass d-1 , over a treatment period of 7 d. At 1 wk post-treatment, sea lice chalimus and mobile stages were reduced by 92 and 74% (both p < 0.001), respectively. At 2 wk post-treatment, chalimus stages were reduced by 41% and mobile stages 61% (both p < 0.001) compared to pre-treatment levels. At 3 wk post-treatment, chalimus stages were still 36% (p < 0.001) lower than pre-treatment levels, but mobile stages had increased to above pre-treatment levels. Our results show that the effects of teflubenzuron are limited to a 3 wk duration, but that with appropriate management, farms could benefit from these reduced lice burdens for longer periods.
Aquaculture, 2018
Diclidophoridae and Capsalidae are families of monogenean parasites that include some of the most pathogenic species for cultured finfish. In this study, the efficacy of praziquantel (PZQ) and a combination anthelmintic (PZQ, ivermectin, pyrantel pamoate and fenbendazole) commercialized under the name of Adecto® (Adler Pharma) were evaluated in vitro against adults and eggs of the diclidophorid Tagia ecuadori and the capsalid Neobenedenia melleni. Freshwater and formalin immersions were also evaluated against T. ecuadori for comparative purposes. In addition, the efficacy in vivo of Adecto® as a bath treatment to eliminate mixed infections as well as the median lethal concentration (LC 50) of this drug in juvenile, healthy bullseye puffer fish (Sphoeroides annulatus) were determined. Triglycerides, hemoglobin, total protein and glucose levels were measured in three groups of fish: uninfected, infected and infected/treated with Adecto®. At the doses tested, PZQ did not have a concentration-dependent effect. Thus, 2.5 mg/L PZQ was 100% effective against adults of T. ecuadori after 20 h, and 3 mg/L killed 87% of N. melleni after 12 h. Adecto® had a concentration-dependent effect. The concentration required to kill all parasites in the minimum time was 20 mg/L Adecto® (12 h for T. ecuadori, and 16 h for N. melleni). Neither PZQ nor Adecto® were effective at inhibiting egg hatching. Adults of T. ecuadori were highly tolerant to freshwater; mortality was < 40% after 24 h, whereas formalin was 100% effective against both adults and eggs in this species. In vivo, 20 mg/L Adecto® administered for 12 h was 100% effective against T. ecuadori; however, it was not 100% effective against N. melleni. Mixed infections provoked increases in hemoglobin and total protein levels in fish. Fish exposed to 20 mg/L Adecto® did not show signs of toxic effect after 24 h. For those fish, the 24-h LC 50 of Adecto® was 30.8 mg/L. This study confirms that PZQ is effective against the parasitic phase of monogeneans but under prolonged exposure. Our results suggest that combination anthelmintics have the potential to kill all parasites in less time; however, alternative combinations should be investigated to find one that is effective under low concentrations to provide a greater safety margin.