Dietary citric acid decreased the theront number of Cryptocaryon irritans (Ciliata) in seawater-adapted tilapia (Oreochromis niloticus).

Cryptocaryoniasis remains a major parasitic disease and economic challenge for marine aquaculture. Cryptocaryoniasis in marine fish is caused by Cryptocaryon irritans (Ciliata). A theront is a motile, free-swimming stage in the life cycle of C. irritans, which is typically the infective stage that actively seeks out a host to initiate infection. Population density and growth rate of theronts were investigated in Nile tilapia, Oreochromis niloticus fed with citric acid-supplemented feed. The experiment involved feeding three diets with graded levels of citric acid (0, control diet, 0.5, 1 and 1.5 g kg-1 diet), to seawater-adapted Nile tilapia (O. niloticus) juveniles for 21 days. The results showed that citric acid in the fish feed had an impact on the theront number of C. irritans in a manner of dose-dependent. In the experimental cohort administered a diet supplemented with 1.5 g kg-1 citric acid, the population density of theronts was observed to be significantly reduced, measured at 29 ± 3.34, as opposed to 473.34 ± 16.48 in the control group at the culmination of the experiment. The observed population growth rate of theronts was significantly higher in the control group than in the group administered the citric acid feed (p < .005). The growth rate (r d-1 ) was 0.12 in control, 0.05 in 0.5 g kg-1 , 0.031 in 1 g kg-1 , and - 0.031 in 1.5 g kg-1 citric acid-supplemented groups. Fish growth and feed conversion ratio were not affected by the citric acid in the feed. In conclusion, the findings of this investigation provide a valuable addition to our understanding of the potential protective effects of citric acid supplementation for fish against the C. irritans parasite. This is evidenced by the observed reduction in theronts present in the water.

Daily patterns in parasite processes: diel variation in fish louse transcriptomes.

Parasites, similar to all other organisms, time themselves to environmental cues using a molecular clock to generate and maintain rhythms. Chronotherapeutic (timed treatment) techniques based on such rhythms offer great potential for improving control of chronic, problematic parasites. Fish lice are a key disease threat in aquaculture, with current control insufficient. Assessing the rhythmicity of fish lice transcriptomes offers not only insight into the viability of chronotherapy, but the opportunity to identify new drug targets. Here, for the first known time in any crustacean parasite, diel changes in gene transcription are examined, revealing that approximately half of the Argulus foliaceus annotated transcriptome displays significant daily rhythmicity. We identified rhythmically transcribed putative clock genes including core clock/cycle and period/timeless pairs, alongside rhythms in feeding-associated genes and processes involving immune response, as well as fish louse drug targets. A substantial number of gene pathways showed peak transcription in hours immediately preceding onset of light, potentially in anticipation of peak host anti-parasite responses or in preparation for increased feeding activity. Genes related to immune haemocyte activity and chitin development were more highly transcribed 4 h post light onset, although inflammatory gene transcription was highest during dark periods. Our study provides an important resource for application of chronotherapy in fish lice; timed application could increase efficacy and/or reduce dose requirement, improving the current landscape of drug resistance and fish health while reducing the economic cost of infection.

Ovicidal effect of essential oils of Lippia alba, Lippia sidoides and Lippia gracilis on the acanthocephalan Neoechinorhynchus buttnerae (Eoacanthocephala: Neoechinorhynchidae).

Acanthocephalosis in tambaqui Colossoma macropomum culture is a limiting factor for the production of the species, being the most recurrent, which makes it necessary to develop strategies to control parasitosis even in the early stages of parasite development. This study aimed to elucidate the morphological characteristics of eggs of the acanthocephalan Neoechinorhynchus buttnerae and the ovicidal effect of the essential oils of Lippia alba, Lippia sidoides, and Lippia gracilis. The parasites were collected from hosts naturally infected with N. buttnerae, and the eggs obtained from the female 'parasites' abdominal cavity were added to 12-well plates containing the essential oils at different dilutions. After the eggs (N = 300) were separated and measured (length and width) with the aid of an optical microscope coupled to a digital program, the viability of the treated eggs was monitored 24 h after treatments, L. gracilis essential oil was 100% effective at the highest concentration, whereas L. sidoides essential oil showed over 50% efficacy at 2 mg/ml, reaching 100% efficacy at all higher concentrations. Lippia. alba essential oil did not show satisfactory efficacy in preventing N. buttnerae egg hatching.

Ononin: A candidate anti-parasitic drug isolated from Spatholobi caulis against infections of Dactylogyrus intermedius (Monogenea).

Dactylogyrus is a common parasitic pathogen, which causes high mortality of fish when presents in large numbers, resulting in serious economic losses. Herbal medicines contain myriad of bioactive compounds is a valuable reserve for developing safe and effective anti-parasite drugs. Here, we conducted bioassay-guided fractionation to isolate and identify the anti-parasitic constituents from Spatholobi caulis. Among five extraction solvents (petroleum ether, chloroform, ethyl acetate, methanol and water), S. caulis methanolic extract had the highest parasiticide activity in Carassius auratus, and therefore subjected to further separation and purification using multiple chromatography methods. One compound exhibiting the strongest parasiticidal activity was obtained and identified as ononin by analyzing its spectral data (NMR and ESI-MS). The EC50 value of ononin against Dactylogyrus was 0.655 mg/L and showed 100% parasiticide activity with 3.0 mg/L. The 24, 48, 72, 96 h LC50 for goldfish were 4.691 (the 95% CI of 4.526-4.873) mg/L, 4.612 (4.441-4.800) mg/L, 4.472 (4.345-4.607) mg/L, 4.288 (4.155-4.428) mg/L, respectively. The present results discovered for the first time that ononin had potent parasiticidal activity and have the potential to be developed as new anti-parasitic drug for the control of Dactylogyrus.

Antiparasitic potential of ethanolic extracts of Carpesii Fructus against Miamiensis avidus in hirame natural embryo cell line and their effects on immune response- and biotransformation-related genes.

Scuticociliatosis, caused by Miamiensis avidus, is a severe parasitic disease affecting marine organisms, particularly Paralichthys olivaceus. The aim of this study was to assess the antiparasitic potential of ethanolic extracts of Carpesii Fructus (EECF), the dried fruit of Carpesium abrotanoides L., which is used in traditional Chinese medicine, in vitro. We found that 50%, 70%, and 100% EECF induced morphological changes in M. avidus, including reduced motility, cell shrinkage, and lysis. Nearly 100% cell lysis was observed in M. avidus after 2 h of treating with 100% EECF. After 24 h, the survival rates of M. avidus treated with 100%, 70%, and 50% EECF were 10%, 20%, and 30%, respectively. Additionally, the mRNA levels of immune response-related (IL-1ß, IL-8, TNF-α, and CD8-α) and biotransformation-related (CYP1A, CYP1B, CYP3A4, and UGT2B19) genes increased with 70% and 100% EECF treatment and decreased with 50% EECF treatment following pretreatment with concanavalin A. The viability of hirame natural embryo (HINAE) cells was reduced by 50%, 70%, and 100% EECF (100 mg/L) and was between 67 and 80%. The IC50 values of 50%, 70%, 90%, and 100% EECF in HINAE cells were 102.3, 42.93, 39.15, and 38.39 mg/L, respectively. These results indicated that 50% EECF was less toxic to HINAE cells than 70% or 100% EECF, while still exhibiting antiparasitic activity against M. avidus. Therefore, we demonstrated the role of EECF as a natural antiparasitic agent against M. avidus. Our findings suggest that Carpesii Fructus has potential use as an antiparasitic agent in the aquaculture industry.

Effects of Extract of Betel Leaf (Piperaceae) against Ectoparasite "Ich" on Pangasius Catfish.

<b>Background and Objective:</b> Freshwater fish aquaculture in Indonesia has grown rapidly, especially the aquaculture of catfish (<i>Pangasianodon hypophthalmus</i>). This species is very good because it is fast-growing and very popular in the market and is important for national food security in many Asian countries. One of the problems faced by freshwater fish aquaculture is ectoparasite <i>Ichthyophthirius multifiliis</i> infection, which often results in significant economic losses to freshwater fish aquaculture. This study aimed to check the effect extract of betel leaf against the ectoparasite, <i>Ichthyophthirius multifiliis</i> in pangasius catfish in an eco-friendly manner. <b>Materials and Methods:</b> A total of 120 fishes with a mean weight of 4.17±0.96 g and a length of 8.5±0.67 cm were examined. Preliminary research was carried out to detect ectoparasites in fish. All fish was infected with ectoparasitic Ich (100%) and were identified as a salt-like granule white spot and a large C-shaped macronucleus. Infected fishes were transferred and equally distributed to the tank (20 L water) which had previously been treated with betel leaf extract for 24 hrs, 3 days, at doses 2.5, 5 and 7.5 g L¹ and control. <b>Results:</b> The results showed that the betel leaf extract solution effect decreased significantly to the number of ectoparasites <i>Ichthyophthirius multifiliis</i>, both in mucus and pangasius catfish and a dose of 7.5 g L¹ was the optimum dose. <b>Conclusion:</b> Betel leaf extract has the potential to control the decrease in the number of ectoparasites, though further phytochemical studies will need to be performed.

Efficacy of the Aqueous Extract of Azadirachta indica Against the Marine Parasitic Leech and Its Phytochemical Profiling.

Zeylanicobdella arugamensis (Hirudinea), a marine parasitic leech, not only resulted in the mortality of the host fish (Groupers) but also caused economic losses. The current study aimed to elucidate the antiparasitic efficacy of the aqueous extract of the Azadirachta indica leaves against Z. arugamensis and to profile the composition via LC-Q Exactive HF Orbitrap mass spectrometry. Different concentrations (25, 50 and 100 mg/mL) of A. indica extract were prepared and tested on the parasitic leeches. The total mortality of leeches was noticed with an exposure to the A. indica aqueous extract. The average times required for the aqueous extract at concentrations of 25, 50 and 100 mg/mL to kill the leeches were 42.65 ± 9.20, 11.69 ± 1.11 and 6.45 ± 0.45 min, respectively, in a dose-dependent manner. The Orbitrap mass spectrometry analysis indicated the presence of five flavonoids (myricetin 3-O-galactoside, trifolin, isorhamnetin, quercetin and kaempferol), four aromatics (4-methoxy benzaldehyde, scopoletin, indole-3-acrylic acid and 2,4-quinolinediol), three phenolics (p-coumaric acid, ferulic acid and phloretin) and two terpenoids (pulegone and caryophyllene oxide). Thus, our study indicates that A. indica aqueous extract is a good source of metabolites with the potential to act as a biocontrol agent against the marine parasitic leech in aquaculture.

Responses to Mineral Supplementation and Salmon Lice (Lepeophtheirus salmonis) Infestation in Skin Layers of Atlantic Salmon (Salmo salar L.).

The crustacean ectoparasite salmon louse (Lepeophtheirus salmonis), which severely affects Atlantic salmon health and welfare is one of the main problems of commercial aquaculture. In the present study, fish were fed a diet supplemented with extra minerals through the inclusion of a commercial additive (Biofeed Forte Salmon), substituting wheat in the control diet, before experimental infestation with salmon lice. Lice counts reduced with time but with no apparent effect of the diets. Further, fish fed the mineral diet had an overall higher number of blue (acidic) mucous cells, while the ratio of purple mucous cells was higher in the mineral diet. The transcriptional response in skin was enhanced at 7 dpc (copepodite life stage) in fish fed the mineral diet including immune and stress responses, while at 21 dpc (pre-adult life stage), the difference disappeared, or reversed with stronger induction in the control diet. Overall, 9.3% of the genes affected with lice also responded to the feed, with marked differences in outer (scale + epidermis) and inner (dermis) skin layers. A comparison of transcriptome data with five datasets from previous trials revealed common features and gene markers of responses to lice, stress, and mechanically induced wounds. Results suggested a prevalence of generic responses in wounded skin and lice-infected salmon.

Evaluation of selected plant extracts for in vitro anti-marine leech (Zeylanicobdella arugamensis) activity.

The aqueous extracts of thirty-four (34) tropical plants were tested in vitro for potential antimarine leech (Zeylanicobdella arugamensis) activity. The anti-leech activity was determined by exposing 8 adult leeches (Z. arugamensis) (9.3 ± 1.5 mm, aged 15 days) to 20 µl of plant extract (0.5 g/ml) for 5 min in a 24-well plate. After 5 min of exposure, the leeches were rinsed and transferred into seawater, to enable them to revive from the effect of the extract. Leech movements were observed from time to time and the numbers of paralyzed or dead leeches were recorded at 5, 20, 30 and 240 min. The efficacy of the plant extract in killing the adult Z. arugamensis during the 5 min exposure is reflected on the anti-leech property of the extract. The anti-leech property of positive plant extracts was also determined at different exposure time (1, 3, 5 min) and dilutions (1/2 (0.25 g/ml), 1/5 (0.1 g/ml) and 1/10 (0.05 g/ml). The extracts of 4 plants (Melastoma malabathricum, Piper betle, Tetracera indica and Etlingera coccinea) demonstrated anti-leech activity. The effects of M. malabathricum, P. betle and E. coccinea extracts on the leeches were very rapid causing death as early as a few seconds upon exposure. However, all four positive plant extracts were found not effective in killing the leeches at 1/10 dilution (0.05 g/ml). A Scanning Electron Microscopy examination on leeches exposed to the positive plant extracts exhibited effects such as protruding proboscis and shrunken or swollen bodies.

Molecular characterization and antiparasitic activity analysis of a novel piscidin 5-like type 4 from Larimichthys crocea.

Cryptocaryon irritans is an obligate parasitic ciliate protozoan that can infect various commercially important mariculture teleosts and cause high lethality and economic loss, especially Larimichthys crocea. Current methods of controlling or preventing this parasite with chemicals or antibiotics are widely considered to be environmentally harmful. The antiparasitic activity of some antimicrobial peptides (AMPs) attracted extensive attention of scholars. In the study, a novel piscidin 5-like type 4 (termed Lc-P5L4) excavated from comparative transcriptome of C. irritans - immuned L. crocea was identified and characterized. Sequence analysis shows the full-length cDNA of Lc-P5L4 is 539 bp containing an open reading frame (ORF) of 198 bp which encodes a peptide of 65 amino acid residues. The genome consists of three exons and two introns which exist in its ORF, and all the exon-intron boundaries are in accordance with classical GT-AG rule (GT/intron/AG). Multiple alignments indicate the signal peptides share highly conserved identity, while mature peptides are more diverse. Phylogenetic analysis displays Lc-P5L4 clusters together with other members of piscidin 5-like family. Next, quantitative Real-time PCR (qRT-PCR) detection found C. irritans infection could upregulate Lc-P5L4 expression level in all tested tissues significantly, it appeared earliest upregulation in the theronts infection stage in the head kidney; the expression contents reached to maximum level in the intestine, gill and muscle during trophonts falling off stage; while it was just upregulated during secondary bacterial infection stage in the liver and spleen. The data showed Lc-P5L4 upregulation time points were in accordance with different infection stages. With recombinant Lc-P5L4 (rLc-P5L4) obtained through Escherichia coli system, in vitro assay showed rLc-P5L4 could cause cilia deactivation, cell bodiesclumping and sticking to each other, then cell membrane rupture and contents leakage. The data illustrated Lc-P5L4 played critical roles in the immune defense against C. irritans infection, and provided another proof that piscidins exhibit multiple anti- C. irritans features.

Hydrogen peroxide treatment and its impacts on Lepeophtheirus salmonis originating from the Bay of Fundy, Canada.

Hydrogen peroxide (H2 O2 ) is used to treat sea lice infections of farmed salmonids in the Atlantic and Pacific Oceans and issues with resistance to this treatment, and others are a major threat to the sustainability of the industry. The objectives of this study were to determine how H2 O2 exposure affects survival and antioxidant-related gene expression in salmon lice (Lepeophtheirus salmonis) collected from the Bay of Fundy, New Brunswick. The maximum recommended dose of H2 O2 is 1,800 mg/L, while the EC50 values (with 95% CI) for the population tested were 1,486 (457, 2,515) mg/L for males and 2,126 (984, 3,268) mg/L for females. Neither temperature nor pretreatment with emamectin benzoate (EMB) impacted survival after H2 O2 exposure. RT-qPCR was performed on pre-adult sea lice exposed to H2 O2 and showed that four genes classically involved in the response to oxidative stress were unchanged between treated and control groups. Seven genes were found to be significantly upregulated in males and one in females. This is the first report on the efficacy and molecular responses of Atlantic Canada sea lice to H2 O2 treatment.

Unveiling the effect of dietary essential oils supplementation in Sparus aurata gills and its efficiency against the infestation by Sparicotyle chrysophrii.

A microencapsulated feed additive composed by garlic, carvacrol and thymol essential oils (EOs) was evaluated regarding its protective effect in gills parasitized by Sparicotyle chrysophrii in Sparus aurata. A nutritional trial (65 days) followed by a cohabitation challenge with parasitized fish (39 days) were performed. Transcriptomic analysis by microarrays of gills of fish fed the EOs diet showed an up-regulation of genes related to biogenesis, vesicular transport and exocytosis, leukocyte-mediated immunity, oxidation-reduction and overall metabolism processes. The functional network obtained indicates a tissue-specific pro-inflammatory immune response arbitrated by degranulating acidophilic granulocytes, sustained by antioxidant and anti-inflammatory responses. The histochemical study of gills also showed an increase of carboxylate glycoproteins containing sialic acid in mucous and epithelial cells of fish fed the EOs diet, suggesting a mucosal defence mechanism through the modulation of mucin secretions. The outcomes of the in vivo challenge supported the transcriptomic results obtained from the nutritional trial, where a significant reduction of 78% in the abundance of S. chrysophrii total parasitation and a decrease in the prevalence of most parasitic developmental stages evaluated were observed in fish fed the EOs diet. These results suggest that the microencapsulation of garlic, carvacrol and thymol EOs could be considered an effective natural dietary strategy with antiparasitic properties against the ectoparasite S. chrysophrii.

DNA sequencing demonstrates the importance of jellyfish in life cycles of lepocreadiid trematodes.

Sequence data were combined with morphological analyses to identify two lepocreadiid trematode species from jellyfishes and fishes. Three species of jellyfish were captured within Port Phillip Bay, Australia, and three species of fish that feed on jellyfish were obtained from Moreton Bay (Queensland) and Port Phillip Bay and Portland (Victoria). The digeneans were distributed throughout most parts of the jellyfish. Opechona cf. kahawai Bray & Cribb, 2003 parasitized the scyphozoan jellyfish Aequorea eurodina and the scombrid fish Scomber australasicus. Cephalolepidapedon warehou Bray & Cribb, 2003 parasitized the scyphozoans Pseudorhiza haeckeli and Cyanea annaskala, and the centrolophid fishes Seriolella brama and Seriolella punctata. Intensities ranged from four to 96 in the jellyfish, and one to 30 in the fish. For both trematode species, internal transcribed spacer 2 of ribosomal DNA sequences from mature adults in the fishes matched those from metacercariae from the jellyfish. This is the first record of larval stages of C. warehou and O. cf. kahawai, and the first use of DNA sequencing to identify digenean trematode metacercariae from jellyfish. Three new host records are reported for C. warehou and two for O. cf. kahawai.

Candidate genes for monitoring hydrogen peroxide resistance in the salmon louse, Lepeophtheirus salmonis.

BACKGROUND: Hydrogen peroxide (H2O2) is one of the delousing agents used to control sea lice infestations in salmonid aquaculture. However, some Lepeophtheirus salmonis populations have developed resistance towards H2O2. An increased gene expression and activity of catalase, an enzyme that breaks down H2O2, have been detected in resistant lice, being therefore introduced as a resistance marker in the salmon industry. In the present study the aim was to validate the use of catalase expression as a marker and to identify new candidate genes as additional markers to catalase, related to H2O2 resistance in L. salmonis. METHODS: A sensitive and an H2O2 resistant laboratory strain (P0 generation, not exposed to H2O2 for several years) were batch crossed to generate a cohort with a wide range of H2O2 sensitivities (F2 generation). F2 adult females were then exposed to H2O2 to separate sensitive and resistant individuals. Those F2 lice, the P0 lice and field-collected resistant lice (exposed to H2O2 in the field) were used in an RNA sequencing study. RESULTS: Catalase was upregulated in resistant lice exposed to H2O2 compared to sensitive lice. This was, however, not the case for unexposed resistant P0 lice. Several other genes were found differentially expressed between sensitive and resistant lice, but most of them seemed to be related to H2O2 exposure. However, five genes were consistently up- or downregulated in the resistant lice independent of exposure history. The upregulated genes were: one gene in the DNA polymerase family, one gene encoding a Nesprin-like protein and an unannotated gene encoding a small protein. The downregulated genes encoded endoplasmic reticulum resident protein 29 and an aquaporin (Glp1_v2). CONCLUSIONS: Catalase expression seems to be induced by H2O2 exposure, since it was not upregulated in unexposed resistant lice. This may pose a challenge for its use as a resistance marker. The five new genes associated with resistance are put forward as complementary candidate genes. The most promising was Glp1_v2, an aquaglyceroporin that may serve as a passing channel for H2O2. Lower channel number can reduce the influx or distribution of H2O2 in the salmon louse, being directly involved in the resistance mechanism.

Nanoemulsions with oleoresin of Copaifera reticulata (Leguminosae) improve anthelmintic efficacy in the control of monogenean parasites when compared to oleoresin without nanoformulation.

This study compared the in vitro anthelmintic activity of Copaifera reticulata oleoresin (200, 400, 600, 800 and 1,000 mg/L) and of nanoemulsions prepared with this oleoresin (50, 100, 150, 200 and 250 mg/L) against monogeneans on the gills of Colossoma macropomum. The major compounds present in the oleoresin of C. reticulata were γ-macrocarpene (14.2%), α-bergamotene (13.6%), ß-selinene (13.4%) and ß-caryophyllene (11.7%). All concentrations of the nanoemulsion and the oleoresin without nanoformulation showed anthelmintic efficacy against monogeneans, and higher concentrations led to more rapid parasite mortality. Structural damages to the tegument of the parasites exposed to C. reticulata oleoresin were observed with scanning electron microscopy. At two hours of exposure, fish showed 100% tolerance to all nanoemulsion concentrations used in the in vitro assays, whereas 100% mortality was shown in the fish exposed to the oleoresin without nanoformulation after one hour. The results of this study suggest that nanoemulsions with oleoresin of C. reticulata have advantages in the control and treatment of monogenean infections in C. macropomum when compared to the oleoresin without nanoformulation. In addition, since nanoemulsions with the C. reticulata oleoresin are safe to control monogeneans, the efficacy of these nanoformulations may be assayed in therapeutic baths to treat C. macropomum infected by monogeneans.

The interaction between temperature and dose on the efficacy and biochemical response of Atlantic salmon to hydrogen peroxide treatment for amoebic gill disease.

Hydrogen peroxide (H2 O2 ) is a commonly used treatment for a range of parasitic diseases of marine finfish, including amoebic gill disease (AGD). While this treatment is partially effective at reducing parasite load, H2 O2 can have detrimental effects on the host under certain conditions. Treatment temperature and dose concentration are two factors that are known to influence the toxicity of H2 O2 ; however, their impact on the outcome of AGD treatment remains unclear. Here, we investigated the effects of treatment temperature (8, 12 or 16°C) and dose concentration (750, 1,000, 1,250 mg/L) on the efficacy of H2 O2 to treat AGD. We demonstrated that a 20-min bath treatment of H2 O2 at all doses reduced both parasite load and gross gill score significantly. Parasite load and gross gill score were lowest in the 1,000 mg/L treatment performed at 12°C. At the high dose and temperature combinations, H2 O2 caused moderate gill damage and a significant increase in the plasma concentration of electrolytes (sodium, chloride and potassium). Taken together, our study demonstrates that higher H2 O2 treatment temperatures can adversely affect the host and do not improve the effectiveness of the treatment.

Morphological updates and molecular description of Heterosentis holospinus Amin, Heckmann, & Ha, 2011 (Acanthocephala, Arhythmacanthidae) in the Pacific Ocean off Vietnam.

Heterosentis holospinus Amin, Heckmann & Ha, 2011 (Arhythmacanthidae) was first described from the striped eel catfish, Plotosus lineatus (Plotosidae) in Halong Bay, Vietnam. New morphological information, scanning electron microscope images, molecular analysis, and Energy Dispersive X-ray analysis (EDXA) of hooks of specimens of H. holospinus from a new collection from the common ponyfish, Leiognathus equulus (Leiognathidae), in Quang Binh, Gulf of Tonkin, Vietnam are reported here for the first time. Additional details of the anterior trunk cone, proboscis hooks, wholly spined trunk, duck-bill-like spines with micropores, and micropore distribution, are described. The unique metal composition of hooks (EDXA) demonstrated a considerably higher level of calcium and phosphorus but lower level of sulfur at the hook basal arch than at the hook tip and edge. An analysis of our new sequences of cytochrome oxidase 1 (COI) showed that H. holospinus had low genetic variation and two haplotypes.

TITLE: Mise à jour morphologique et caractérisation moléculaire d'Heterosentis holospinus Amin, Heckmann & Ha, 2011 (Acanthocephala, Arhythmacanthidae) de l'Océan Pacifique au large du Vietnam. ABSTRACT: Heterosentis holospinus Amin, Heckmann & Ha, 2011 (Arhythmacanthidae) a été décrit pour la première fois chez le poisson-chat Plotosus lineatus (Plotosidae) dans la baie d'Halong, au Vietnam. Des nouvelles informations morphologiques, des images au microscope électronique à balayage, une analyse moléculaire et une analyse par rayons X à dispersion d'énergie (EDXA) des crochets de spécimens d'H. holospinus provenant d'une nouvelle récolte de Leiognathus equulus (Leiognathidae), à Quang Binh, golfe du Tonkin, Vietnam sont données pour la première fois. Des détails supplémentaires sur le cône antérieur du tronc, les crochets du proboscis, le tronc entièrement épineux, les épines en forme de bec de canard avec des micropores et la distribution des micropores sont décrits. La composition métallique unique des crochets (EDXA) a démontré une teneur en calcium et en phosphore considérablement plus élevée, mais une teneur en soufre plus faible au niveau de l'arcade basale du crochet qu'à la pointe et au bord du crochet. Une analyse de nos nouvelles séquences de cytochrome oxydase 1 (COI) a montré qu'H. holospinus présentait une faible variation génétique et deux haplotypes.

Effect of nutraceuticals on acanthocephalan Neoechinorhynchus buttnerae and its toxicity to the host tambaqui Colossoma macropomum.

The production of tambaqui Colossoma macropomum has been undergoing financial losses due to parasitic infection by the acanthocephalan Neoechinorhynchus buttnerae, raising an alert for aquaculture in South America. The lack of adequate treatment and use of unlicensed chemicals encourages research for alternative solutions with minimal side effects. The objectives of this study were to evaluate the in vitro antiparasitic potential of commercial nutraceutical products (Natumix® and BioFish®) against N. buttnerae and to assess the respective in vivo toxic effects on the host tambaqui. For in vitro assays, parasitized fish were necropsied for acanthocephalans sampling. The parasites were exposed to three concentrations (0.078, 0.313 and 1.25 mg/ml) of each product, as well as controls (one without product and another with a solubilizer). For the in vivo acute toxicity test, juvenile fish (<0.1 g) were exposed to five increasing concentrations of each product. Mortality of tambaqui was recorded at 24, 48, 72 and 96 h. The estimated lethal concentration (LC) for 10, 50, 90 and 99% of fish was determined to classify the toxicity of the products on the target species. After in vitro efficacy tests, the highest concentrations (1.25 mg/ml) caused 100% mortality of the parasites in both products, but only Natumix® caused 100% mortality using the intermediate concentration (0.313 mg/ml) after 24 h. According to the acute toxicity result, the LC50 classified the nutraceutical products as slightly toxic for tambaqui. The tested products had a parasiticidal effect on N. buttnerae, and the toxicity test showed that both products have therapeutic potential when added to the diet.

Anthelminthic potential of the Ficus insipida latex on monogeneans of Colossoma macropomum (Serrasalmidae), a medicinal plant from the Amazon.

INTRODUCTION: Herbal therapy is a potentially beneficial alternative for fish aquaculture, since it may be cheaper and more effective than chemotherapy. The aim of this study was to investigate the in vitro efficacy of Ficus insipida latex on monogeneans of Colossoma macropomum gills. MATERIALS AND METHODS: To evaluate the anthelmintic activity, four concentrations of F. insipida latex (250, 500, 750 and 1000 µL/L) and exposure time to cause immobilization on monogeneans were used. In addition, two control groups, being one with water from the breeding tank and the other with breeding water from the tank + 70% ethyl alcohol were used. RESULTS: At the concentration of 250 µL/L of F. insipida latex, the immobilization of the monogeneans occurred after 4 h of exposure, while at the concentration of 500 µL/L, it occurred after 2 h. At the concentrations of 750 and 1000 µL/L of F. insipida latex, the immobilization of the monogeneans occurred after 1 h and 30 min, respectively. After exposure to 250 µL/L of F. insipida latex, 100% of immobilization of monogeneans was observed within 4 h, to 500 and 750 µL/L, 100% immobilization occurred within 4 h and to 1000 µL/L, 100% mortality occurred after 2 h. CONCLUSIONS: Thus, we recommended the use of 1000 µL/L of F. insipida latex for therapeutic baths in of C. macropomum against monogeneans, after previous test of toxicity.

Efficacy and antiparasitic mechanism of 10-gingerol isolated from ginger Zingiber officinale against Ichthyophthirius multifiliis in grass carp.

Ichthyophthirius multifiliis is a ciliate parasite of freshwater fish with a global distribution and results in severe economic losses in aquaculture. The present study aimed to investigate the efficacy and antiparasitic mechanism of active compounds isolated from Zingiber officinale against I. multifiliis. Three compounds were isolated from the Z. officinale extract and identified as 10-gingerol, 6-dehydroshogaol, and 6-dehydro-10-gingerol. 10-gingerol demonstrated the greatest antiparasitic efficacy in vitro. 10-gingerol resulted in 100% mortalities of theronts, nonencysted tomonts, and encysted tomonts at concentrations of 2, 8, and 16 mg/L, respectively. 10-gingerol significantly reduced theronts infectivity (p < 0.05) at a concentration of 1 mg/L, and it was effective in treating infected grass carp and protecting naïve fish from I. multifiliis infestation at a concentration of 4 mg/L. The antiparasitic mechanism might be attributed to the increase of intracellular osmotic pressure, accumulation of free radicals, and membrane damage of I. multifiliis post 10-gingerol treatment. The study demonstrated that 10-gingerol had the potential as a therapeutic agent against I. multifiliis.