Use of flubendazole as a therapeutic agent against rotifers ( Brachionus plicatilis ) in intensive cultures of the harpacticoid copepod Tisbe holothuriae (original) (raw)
Related papers
The American Journal of Tropical Medicine and Hygiene
Dracunculus medinensis, also known as the African Guinea worm, is the causative agent of dracunculiasis and the focus of the global Guinea Worm Eradication Program (GWEP). Transmission of D. medinensis to humans occurs primarily by drinking water containing cyclopoid copepods infected with third-stage D. medinensis larvae. A common intervention to interrupt transmission and decrease the number of copepods in infected water bodies is the application of the organophosphate larvicide Abate® (temephos). However, the use of alternative compounds to help decrease copepod populations would be beneficial to the GWEP. We compared the immobilization of copepods by three compounds: Abate, Natular® (spinosad), and diflubenzuron. Our results confirm that neither diflubenzuron nor Natular immobilized copepods as quickly or as effectively as Abate. However, doubling or tripling the suggested concentration of Natular resulted in immobilization rates similar to Abate over 72 hours of continuous expo...
The parasitic copepod, Pseudocaligus apodus is recorded for the first time on the gills of the cultured flathead grey mullet, Mugil cephalus, in Egypt. Morphological comparison between the both sexes of the parasite shows that all appendages are similar except, antenna, postantennal process, maxilliped and sternal furca. Each sex of the parasite has its characteristic genital segment and ornamented caudal rami. The unique mode of attachment of the parasite to its fish host is by the piercing action of both maxilliped and antenna. The attachment of the parasitic copepod causes degenerative changes which could extend beyond the epithelial layer resulting in responsive hyperplasia and necrosis of the gill epithelium at the site of attachment. Surprisingly, the present investigation has revealed that plant extract (Piper nigrum) is more effective than the synthetic drug (Entophar) against the parasitic copepods. Also, there is a significant decrease in life span of the treated parasites with the increase in concentration of antiparasitic agents. The treated parasites undergo speed successive concentrations and relaxations followed by a dramatic inhibition in the activity of the parasite. Subsequently, the parasites undergo body swelling, expulsion with the extrusion of their internal organs to outside. The present results have concluded that possible safe way for wiping the parasitic copepod, the infested fishes should be maintained for a short time (15-16 minutes) in small tanks containing concentrations (10-50ppm) of plant extract, Piper nigrum.
Environmental Toxicology and Chemistry, 2004
Fipronil is a novel ␥-aminobutyric acid receptor-specific phenylpyrazole insecticide commonly used near estuarine environments for rice production, turf-grass management, and residential insect control. In this study, we evaluated the acute, developmental, and reproductive toxicity of fipronil to the estuarine harpacticoid copepod Amphiascus tenuiremis. Fipronil was highly toxic to A. tenuiremis (adult 96-h median lethal concentration [LC50] ϭ 6.8 g/L) and was more toxic to male copepods (96-h LC50 ϭ 3.5 g/L) than to nongravid female copepods (96-h LC50 ϭ 13.0 g/L). By using a newly developed 96-well microplate-based life-cycle toxicity test, we successfully reared single individuals of A. tenuiremis to adulthood in 200-l microwells and concurrently assessed developmental and reproductive effects (after paired virginal matings) of environmentally relevant aqueous fipronil concentrations (0.16, 0.22, and 0.42 g/L measured). Throughout the entire life cycle, copepod survival in all treatments was Ͼ90%. However, fipronil at 0.22 g/L and higher significantly delayed male and female development from stage 1 copepodite to adult by approximately 2 d. More importantly, fipronil significantly halted female egg extrusion by 71% in the 0.22-g/L fipronil treatment, and nearly eliminated reproduction (94% failure) in the 0.42-g/L fipronil treatment. A three-generation Leslie matrixbased population growth model of fipronil reproductive and life-cycle impacts predicted a 62% decline in population size of A. tenuiremis relative to controls at only 0.16 g/L.
Aquatic Toxicology, 2006
In ecotoxicology, there is an increasing demand for sensitive sublethal endpoints. The primary aim of the present study was therefore to evaluate the relative sensitivity and usefulness of four sublethal endpoints -development time, body length, RNA content and growth rate -in the harpacticoid copepod Nitocra spinipes, using the reference molecule Simvastatin. Development time decreased significantly at low sublethal concentrations of Simvastatin (p < 0.001; F = 13.249; 0.16-1.6 g L −1 ), while RNA content and body length increased significantly at 0.16 g L −1 (p < 0.001; F = 6.13) and 1.6 g L −1 (p < 0.01; F = 2.365), respectively. The growth rate increased significantly at 0.16-5 g L −1 (p < 0.01-0.001). Hence, significant responses of growth-related traits were observed already at 0.16 g L −1 , which is about 5000 times lower than the acute toxicity (96 h-LC 50 : 810 g L −1 ). These results show that all assayed endpoints are very sensitive and indicate that current ecotoxicity testing used for environmental protection activities may underestimate the risk for harpacticoid copepods and most likely for other small invertebrates, when relying exclusively on acute toxicity measurements.
Ecotoxicology and Environmental Safety, 2009
We evaluated effects of six algal species in 25 combinations on growth and reproduction of the harpacticoid copepod Nitocra spinipes. In the first lifecycle test, Rhodomonas salina, Phaeodactylum tricornutum, and Dunaliella tertiolecta were used. The results showed that R. salina was the best food, whereas P. tricornutum (0% development success) and D. tertiolecta (41.7% malformations) were poor food items. In the second lifecycle test, a mixture of R. salina, Tetraselmis suecica, and Thalassiosira weisflogii (selected from screening tests) was tested together with a mono-diet of R. salina. Also in this test, copepods fed R. salina performed better (i.e. had higher survival and reproductive success) compared with the other treatment. We conclude that R. salina is appropriate to use as food in toxicity testing with N. spinipes, whereas some of the algae commonly used as feed in ecotoxicological tests with other copepods had detrimental effects on the development, reproduction, and survival of N. spinipes.
Fluconazole induces teratogenic effects in the tunicate Phallusia mammillata
Environmental Toxicology and Pharmacology, 2007
Fluconazole (FLUCO) is an azole derivative used to treat fungal and yeast infections. Embryotoxicity tests on the ascidian Phallusia mammillata were performed to evaluate the effects of this drug. FLUCO proved to have strong consequences on P. mammillata development. Incidence of malformations and of lethality increased in a dose dependent way. Probit analysis showed that FLUCO had a high TI value (Teratogenic Index, LC 50 /TC 50 ), thus this substance could be classified as a teratogenic compound for ascidians. Larvae exposed to FLUCO showed a typical phenotype characterized by malformations restricted to the trunk region: the trunk appeared round in shape with flat palps, the sensory vesicle cavity was absent or reduced and the anterior central nervous system failed to correctly differentiate. These anomalies resulted similar to those induced by retinoic acid (RA) treatment. Thus, it could be hypothesized that FLUCO and RA may act with a similar pathogenic mechanism in ascidian larvae, as it has been proposed for mammals.
Sublethal effects of the toxic dinoflagellate Karenia brevis on marine copepod behavior
Journal of Plankton Research, 2007
Apart from grazing interactions, little is known regarding the sublethal effects of Karenia brevis cells on copepod behavior. We conducted grazing and mortality experiments with K. brevis cells and brevetoxins (PbTx-2), establishing routes of toxicity for the copepods Acartia tonsa, Temora turbinata and Centropages typicus. Subsequent behavioral experiments determined whether copepod swimming and photobehavior, both behaviors involved in predator avoidance, were impaired at sublethal K. brevis and PbTx-2 levels. Copepods variably grazed toxic K. brevis and non-toxic Prorocentrum minimum at bloom concentrations. Although copepods accumulated brevetoxins, significant mortality was only observed in T. turbinata at the highest test concentration (1 Â 10 7 K. brevis cells L 21). Acartia tonsa exhibited minimal sublethal behavioral effects. However, there were significant effects on the swimming and photobehavior of T. turbinata and C. typicus at the lowest sublethal concentrations tested (0.15 mg PbTx-2 L 21 , 1 Â 10 5 K. brevis cells L 21). Although physiological incapacitation may have altered copepod behavior, starvation likely played a major role as well. These data suggest that sublethal effects of K. brevis and brevetoxin on copepod behavior occur and predicting the role of zooplankton grazers in trophic transfer of algal toxins requires knowledge of species-specific sublethal effects.
Fluconazole induces teratogenic effects in the tunicate< i> Phallusia mammillata
2007
Fluconazole (FLUCO) is an azole derivative used to treat fungal and yeast infections. Embryotoxicity tests on the ascidian Phallusia mammillata were performed to evaluate the effects of this drug. FLUCO proved to have strong consequences on P. mammillata development. Incidence of malformations and of lethality increased in a dose dependent way. Probit analysis showed that FLUCO had a high TI value (Teratogenic Index, LC 50 /TC 50), thus this substance could be classified as a teratogenic compound for ascidians. Larvae exposed to FLUCO showed a typical phenotype characterized by malformations restricted to the trunk region: the trunk appeared round in shape with flat palps, the sensory vesicle cavity was absent or reduced and the anterior central nervous system failed to correctly differentiate. These anomalies resulted similar to those induced by retinoic acid (RA) treatment. Thus, it could be hypothesized that FLUCO and RA may act with a similar pathogenic mechanism in ascidian larvae, as it has been proposed for mammals.
Western Indian Ocean …, 2004
The effect of water flooding, organic fertiliser application and salinity manipulation in stimulating the hatching of rotifer resting eggs was investigated during the dry season (in August/September 1999) in simulation tanks and earthen ponds at Makoba, Zanzibar,. The majority of hatched zooplankton included rotifers, identified as Brachionus plicatilis, and other zooplankton such as copepods and protozoa were present in small numbers. The number of rotifers hatched in simulation treatments with low salinity was higher than the values in treatments containing undiluted seawater. Up to 22 ± 1.5 (mean ± SE) rotifers/ml were counted in treatments with low salinity, whereas only a maximum of 13 ± 1. rotifers/ml were found in high-salinity treatments. On the other hand, although salinity in earthen ponds was similar (32-33‰), the ponds flooded and fertilised with chicken manure yielded significantly more rotifers (26 ± 1 / ml), compared to a maximum of only 8 ± 0.5 rotifers/ml counted in the control unfertilised pond. These results suggest that it is possible to induce hatching and production of rotifers by manipulating salinity and fertility of ponds. The reared rotifers can be harvested and used to feed finfish larvae elsewhere.