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Controlled-release technology was introduced to offer an incredible guarantee for improving the adequacy of the existing active molecules and solving the related environmental troubles. Our study attempts to utilize the controlled release of alginate niclosamide-l-glutamate formulation to control Schistosoma mansoni intermediate host (Biomphalaria alexandrina snail) and to evaluate the amount of niclosamide released in relation to its attraction and mortality rate. Results: polymeric formulations B3-4b at a concentration of 0.3 ppm niclosamide in combination with 75% l-glutamate caused 100% mortality of B. alexandrina snails 5-day post-exposure. Stable snails mortality rates were obtained post-exposure to polymer B3-4a (R2 = 0.9823). The high potential of the polymeric formulations B3-4a (0.2 ppm niclosamide and 75% l-glutamate) to attract snail toward polymer direction was manifested by 80%, 14%, 6% and 0% snail in areas (I), (II), (III) and (IV), respectively 24-hr post-exposure. While, B3-4a showed a high mortality rate of attracted snails resembled by 40% and 100% on the 2nd and 7th days, respectively. The modified structure of polymer-niclosamide-l-glutamate prolonged the validity and efficiency of the niclosamide. Slowly released molluscicide was effective at lower concentrations with increasing concentrations of the applied attractant that could reduce its toxicity to the water ecosystem. Keywords: Biomphalaria alexandrina, Control of schistosomiasis, Controlled release molluscicides, l-glutamate attractant, Niclosamide

Procambarus clarkii juveniles were used as an aquatic model to investigate growth performance and immune parameters after 6 weeks of feeding with supplementation of ten experimental diets containing 1%, 2%, 3% Biogen® (as probiotics), Allium sativum (garlic) and Cynodon dactylon (as immunostimulant) and one concentration (3 g/L) of sodium alginate (as prebiotics), compared with feeding on control basal diets only. All supplementation diets increased survival rates and wet weight, while, 1% and 2% C. dactylon showed a significant ( P ⩽ 0.05) increase in weight gain percentage (WG%), and specific growth rate (SGR). Feeding with diet containing 2% Biogen®, 2% and 3% garlic and sodium alginate showed a significant ( P ⩽ 0.05) increase in SGR rate after 6 weeks. Synergetic effect of 1% and 3% Biogen® and sodium alginate in total hemocytes count (THC) which increased significantly ( P ⩽ 0.05) after 6 weeks of feeding. Prophenoloxidase activity increased with all supplemented diets. While SOD increased significantly with 3% C. dactylon , 1% and 3% garlic and 2% Biogen. The results indicated that Biogen®, garlic, C. dactylon and sodium alginate inclusion with a basal diet had the potential to improve the growth and immune response of P. clarkii juveniles, hence this enables us to use the three supplementation diets in fish and prawn farms to improve their growth and immune parameters.

Schistosomiasis is one of the most important public health problems in many developing countries. The present study was conducted to investigate the effect of the polymeric niclosamide formulations against Biomphalaria alexandrina snails, the intermediate host of Schistosoma mansoni in Egypt. Three new polymeric formulations were prepared for the molluscicide niclosamide. The formulations were prepared either by the chemical modifications of poly(glycidyl methacrylate) or by physical entrapment of the niclosamide in calcium alginate beads. The release of the niclosamide from the polymeric formulations was investigated. The activity of the prepared formulations against Biomphalaria alexandrina was investigated. The results obtained revealed higher potency for polymerized niclosamide B3 than B1; the lowest potency was revealed for B2. After an exposure period of 24 hours, LC(50) values were 0.073, 0.098 and 1.09 ppm for B3, B1 and B2, respectively. In addition, the molluscicidal potency of the test polymeric niclosamide was age-dependent, where old snails were more tolerant to the test solutions than young and newly hatched snails. The results also indicated that the molluscicidal activity of B3 was extended for 21 days and 17 days for B1, compared with 5 days for free niclosamide. However, the molluscicidal potency of the polymerized niclosamide was increased after boiling for one hour, and was increased with increasing the pH of the medium to pH 9. In addition, their potency was increased with decreasing the water hardness concentrations (CaCO(3)).Molluscicidal activity of free niclosamide and its polymeric formulations vs. exposure time.

In this study, the chronic effects of diethyldithio carbamate (DDC) on the fecunditiy and on some oxidative and anaerobic enzymes of Biomphalaria alexandhna snails, the intermediate host of Schistosomiasis mansoni in Egypt, were evaluated. The data obtained showed that the exposure of snails to sublethal concentrations of DDC reduced the egg laying capacity of the snails. The hatchabilily and survival rates of eggs, treated with very low concentrations of DDC were significantly reduced. All of the above effects were found lo be concentration and time dependent. Also, these DDC concentrations resulted in a significant decrease in the activity of lactate oxidase (LO), succinate oxidase (SO), known to activate vitellogenesis, and pyruvate kinase (PK), the key enzyme of anaerobic metabolism. On the other hand, the levels of transaminases (AST, ALT) of the exposed snails to DDC concentrations tested were not affected. At the same time, the glycogen content of the treated snails was lowered significantly. Moreover, the tested DDC concentrations caused degenerative changes to