Effect of the plant Cupressus macro-carpa (Cupressacea) on some haematolo-gical and biochemical parameters of Biomphalaria alexandrina snails.

The dry powder of the plant aereal part; Cupressus macro-carpa (Cupressacea) was tested against Biomphalaria alexandrina. LC50 & LC90 values were 59.5 & 98.8 ppm, respec-tively. Exposure of B. alexandrina to sublethal concentrations (LC0, LC10 & LC25) of C. macrocarpa for three weeks signi-ficantly decreased the number of circulating hemocytes. The magnitude of reduction was increased with increasing of the tested concentration. The main type of cell in the hemolymph of B. alexandrina was the granulocyte (71.8%), followed by large round cells or hyalinocytes (19.0%) and small round cells or undifferentiate cells (9.2%). The percentage of different hemocyte categories was changed in treated snails. In snails maintained at LC25, showed significantly higher percentages of small round cells than controls, 56.2% & 9.2% respectively. Maintainence of B. alexandrina in sublethal concentrations for three weeks significantly reduced protein & hemoglobin content in the hemolymph. Reduction in enzyme activities occurred in the hemolymph and tissues of treated snails. The enzymes were pyruvate kinase (PK), lactat dehydrogenase (LDH), hexokinase (HK) and phosphoenol pyruvate carboxy kinase (PEPCK) which are very important in metabolism of the protein and carbohydrate. The infectivity of Schistosoma mansoni miracidia was greatly reduced by exposure to the sublethal concentrations (LC0, LC10 & LC25) of Cupressus. Infection rate of B. alexandrina reached to 54.5%, 37.5% & 16.7%, respectively compared to control (81.25%). Duration of cercarial shedding and the total periodic cercarial production/snail showed significant reduction while the parasite incubation period was significantly longer (p<0.05).