Monogenean Neobenedenia Girellae Research Articles

Antiparasitic Efficacy of Crude Plant Extracts and Compounds Purified from Plants against the Fish Monogenean Neobenedenia girellae.

Neobenedenia girellae is a pathogenic ectoparasite of many marine fishes, and it causes major epidemics in marine aquaculture. In this study, the efficacy of ethanol extracts of huangqi Astragalus membranaceus (known as milkvetch in North America), guanzhong Dryopteris setosa (known as beaded wood fern in North America), gancao Glycyrrhiza uralensis (known as Chinese licorice in North America), danshen Salvia miltiorrhiza (known as red sage in North America), and pomegranate Punica granatum, as well as seven phytochemicals (10-gingerol, curcumin, cynatratoside-C, emodin, kuwanon-G, kuwanon-O, and sophoraflavanone-G), against adult N. girellae was investigated. In vitro results indicated that pomegranate extract killed all adult N. girellae at a 62.5-mg/L concentration with an 8-h exposure, but gancao extract did not cause 100% mortality until a 1,000-mg/L concentration was used. Additionally, all adult N. girellae died after an 8-h exposure to cynatratoside-C, kuwanon-G, kuwanon-O, or sophoraflavanone-G at a concentration of 125mg/L. Curcumin, emodin, and 10-gingerol at a concentration of 1,000mg/L did not kill all parasites after an 8-h exposure. These findings demonstrate that plant extracts and active phytochemicals are potential sources of botanical drugs for controlling N. girellae infection in aquaculture.

Biochemical composition of marine monogenean parasite eggs

This study on the eggs of the tropical monogenean Neobenedenia girellae presents the first detailed quantitative biochemical information of a marine parasite species’ eggs. Moisture and protein composed the majority of the contents of freshly laid eggs (79.12±0.82 and 11.51±0.49% respectively) followed by lipid (2.50±0.15%). Lipids were composed of approximately equal amounts of saturated, monounsaturated, and polyunsaturated fatty acids and the predominant lipid class was triacylglycerol (33.82±1.20%). This study represents a fundamental step towards a better understanding of the early life biology of this important species of parasite.

Antiparasitic effect of calcium and magnesium ion-free buffer treatments against a common monogeneanNeobenedenia girellae

This study investigated a new effective method for controlling the capsalid monogenean Neobenedenia girellae. We examined in vitro and in vivo the effect on the percentage survival of N. girellae in buffers containing different metallic ions. Decreased survival was observed in buffer solutions lacking two ions. In particular, the percentage survival of N. girellae was significantly decreased after 10 min exposure to buffer containing neither Ca(2+) nor Mg(2+). Transmission electron microscopic observations showed that treatment with this buffer disrupted intercellular junctions. This significant effect on percentage survival of N. girellae using Ca(2+)/Mg(2+)-free buffer was confirmed in an in vivo assay. Ca(2+)/Mg(2+)-free buffer had no effect on the condition of the host, spotted halibut Verasper variegates (Pleuronectidae). These results suggest that treatment with Ca(2+)/Mg(2+)-free buffer is a new effective control method, which could replace existing control methods.

A small ciliary surface glycoprotein of the monogenean parasiteNeobenedenia girellaeacts as an agglutination/immobilization antigen and induces an immune response in the Japanese flounderParalichthys olivaceus

The capsalid monogenean Neobenedenia girellae, a parasite of seawater fishes, was found to express an antigen that elicits antibodies in rabbits, and these antibodies had agglutination/immobilization activity against N. girellae larvae (oncomiracidia) in vitro. Indirect immunofluorescence staining of N. girellae oncomiracidia showed that this agglutination/immobilization antigen was expressed on the surface of cilia. An intraperitoneal injection of ciliary proteins (either sonicated or intact) with adjuvant also elicited agglutinizing/immobilizing antibodies in sera from Japanese flounder, Paralichthys olivaceus. These antisera showed a clear correlation between anti-ciliary antibody levels (measured by enzyme-linked immunosorbent assays) and their agglutination/immobilization activity. Anti-ciliary antibody levels in Japanese flounder reached a plateau at 39 days after booster immunization and were significantly higher in the two immunized groups (injection of sonicated or intact cilia) as compared with control fish (injection of bovine serum albumin; ANOVA, Tukey's test, P < 0.01). Anti-ciliary antibodies were also found in fish mucus; however, there was no correlation between fish serum anti-ciliary antibody levels and mucus antibody levels. A Triton X-114-soluble 8 kDa glycoprotein of the ciliary integral membrane fraction is a plausible candidate for the agglutination/immobilization antigen based on SDS-polyacrylamide gel electrophoresis and immunoblot analyses with rabbit and fish antisera.

Susceptibility of spotted halibut Verasper variegatus (Pleuronectidae) to infection by the monogenean Neobenedenia girellae (Capsalidae) and oral therapy trials using praziquantel

This study investigated the susceptibility of spotted halibut Verasper variegatus (Pleuronectidae) to infection by the capsalid monogenean Neobenedenia girellae and sought an effective treatment method against this monogenean species in advance of its culture to enable a stable production of V. variegatus by farming. Our results showed that V. variegatus is susceptible to N. girellae. In oral therapy trials, the anthelmintic praziquantel in feed was found to be antiparasitic against infestation by N. girellae on V. variegatus, and a low-dose treatment for a long period, such as 40 mg/kg body weight (BW)/day for 11 days, was more effective compared with treatment of a high dose for a short period (i.e., 150 mg/kg BW/day for 3 days). The number of N. girellae on V. variegatus was significantly lower than for Japanese flounder Paralichthys olivaceus (Paralichthyidae) when both species were exposed to oncomiracidia in the same aquarium. Considering the lower susceptibility of V. variegatus for this parasite species and the effectiveness of using praziquantel, V. variegatus may be a promising species for stable production by aquaculture.

Response of the Monogenean Neobenedenia girellae to Low Salinities

Effects of different salinities (8, 17, 24, 27, 30 and 34 ppt) on the egg laying, egg hatching and oncomiracidial swimming behavior of the monogenean Neobenedenia girellae were examined in vitro . Egg laying ability was affected at 8, 17, 24 ppt salinity and the number of laid eggs at these salinities were significantly lower than at 34 ppt salinity (control). Egg hatching rates at 8 and 17 ppt salinity were significantly lower than that of the control. The rate of non-motile oncomiracidia at 8 and 17 ppt salinity was significantly higher than that of the control. The results suggest that culturing fish in seawater with low salinity could be effective to control N. girellae infections in aquaculture.

Neobenedenia girellae (Hargis, 1955) Yamaguti, 1963 (Monogenea: Capsalidae) from Cultured Marine Fishes of Japan

The monogenean Neobenedenia girellae (Hargis, 1955) Yamaguti, 1963 is redescribed and reported for the first time in Japan. The parasite was recovered from the body surface, fins, and occasionally from the eyes of 14 species, comprising 5 families of cultured marine fishes from several localities in southwestern Japan. Neobenedenia melleni (MacCallum, 1927) sensu Kaneko et al. (1988) from tilapia (Oreochromis mossambicus) in Hawaii is synonymized with this species. Examination of original specimens (syntypes) of N. melleni sensu MacCallum (1927) revealed differences with N. girellae in having a wide and rounded body, a prominently large anterior hamuli, and absence of glands of Goto. This Neobenedenia from Japanese fishes sometimes showed an unusual morphology of the individual parts of the median sclerites. The potential threat of N. girellae to the health of cultured Japanese fishes is indicated by its low host specificity, wide distribution, and ability to cause mortality due to heavy infection. Unregulated importation of amberjack fry (Seriola dumerili) to Japan appears to be the source of N. girellae infection in Japanese fishes since 1991.

Reproduction and Growth of Neobenedenia girellae(Monogenea: Capsalidae), a Skin Parasite of Cultured Marine Fishes of Japan.

Under laboratory conditions at 25°C, the monogenean Neobenedenia girellae (Hargis, 1955) rapidly developed on Japanese flounder (Paralichthys olivaceus), and it took 15-17 days from egg to maturation.The whole process of egg formation from the release of oocytes from the germiduct to laying of egg capsule required a mean of 73sec. At room temperatures between 27-30°C, large adults laid a mean of 35.4eggs/h, while smaller ones a mean of 12.2eggs/h. Eggs began to hatch after incubation for 5-6 days at 25°C with natural cycle of illumination, but no hatching occurred at 15°C. It took 10-11 days to reach sexual maturity where the minimum body size for an egg-laying adult was 2.1mm. When compared with other benedeniine species, N.girellae required a shorter time and a smaller body size to attain maturity and showed a high level of egg output. One-day old larvae were found only on the fins of Japanese flounder.As the parasites grew, they were found not only on the fins but most commonly on the dorsal and ventral body surface of fish, suggesting migration of the parasite from the fins.

Phyllodistomum scrippsi sp. n. (Digenea: Gorgoderidae) and Neobenedenia girellae (Hargis, 1955) Yamaguti, 1963 (Monogenea: Capsalidae) from the California Sheephead, Pimelometopon pulchrum (Ayres) (Pisces: Labridae)

Phyllodistomum scrippsi sp. n. is described from the urinary bladder and Neobenedenia girellae is reported from the skin of Pimelometopon pulchrum from La Jolla, California. Phyllodistomum scrippsi differs from P. borisbychowskyi in possessing lobed vitellaria, fewer extracecal uterine loops, irregular to lobed gonads, and larger eggs; and from P. acceptum in possessing a short esophagus, nondigitiform vitelline lobes, and an oral sucker larger than the acetabulum. An annotated checklist of trematodes parasitizing P. pulchrum is given. A specimen of the California sheephead, Pimelometopon pulchrum (Ayres), was collected off La Jolla, California, in March 1974. The urinary bladder contained eight specimens of an unreported species of Phyllodistomum Braun, 1899 (Digenea: Gorgoderidae), and over 100 specimens of the monogenean Neobenedenia girellae (Hargis, 1955) Yamaguti, 1963, were found on the skin. The digeneans were fixed in situ with hot AFA, removed from the urinary bladder, and stored in 70% ethanol. Monogeneans were collected as suggested by Rogers (1966) and stored in 10% formalin. All worms were stained with Mayer's hematoxylin and mounted in Canada balsam for study as whole mounts. Figures were drawn with the aid of a camera lucida. All measurements are in microns unless