Effect of three dopmant oil on schistosomiasis and fascioliasis vector snails and its relation with some non traget snails

Three oils were tested for their molluscicidal activity, Caple-2, Kemasol and super-max. super-max had the strongest toxic effect on B. alexandrina and other snail species. Its LC50 was 0.53 ppm, meanwhile LC50 of kemasol 3.2 ppm and 4.21ppm for Caple 2. the LC50 and LC90 of the oils were lower in lymneae natalensis as compared to B. alexandrina. The LC50 and LC90 of the oils against non-target snails [physa acuta, Helisoma duryi,planorbis planorbis and melanoides tuberculata] were higher as compared to B. alexandrina. Hatchability of snails' eggs exposed to super-max [3.0 and 5.0 ppm] was stopped completely and 1.0 ppm showed the lower percent of egg hatchability 22.7%. Caple 2 kemasol did not affect eggs hatchability. Super-max had the strongest harmful effect on both miracidia and cercarias of S. mansoni.100% mortality values were obtained for both larval stages after 8 and 9 minutes respectively when maintained at LC50. 100%mortality of miracidia occurred after 35 and 155 minutes when maintained at LC50 of kemasol and caple 2 respectively. The infection rate of B. alexandrina with S. mansoni miracidia was greatly reduced by the sublethal concentrations of the oils. The reduction of infection rate was higher in snails treated with supermax [42.9%].A highly significant reduction of total cercarial production per snail was in the experimental groups as compared with control. The prepatent period of treated snails was prolonged compared to control. Moreover, Total protein content and enzyme activities of snails treated with LC10 of oils showed a significant reduction as compared with control in the haemolymyph. there was an increase of protein control in haemo-ALKP enzyme activity was slightly increased in haemolyph of experimental groups than controls and was significantly higher in the tissues as compared to control. ALT enzyme activity in haemolymph of experimental groups was higher than control but lower in tissue. AST enzyme activity was higher in haemo- lymph and tissue of experimental groups than control. The SDS-PAGE pattern of tissue proteins from treated B. alexandrina and controls showed different oils effects on the synthesis of within snails yielded a complex pattern of polypeptides ranging in molecular weight between 13.775 to 156.7 kDa. Many bands were present in treated snails. AT least, one band was detected for snails treated with each of the oils and not in controls. The difference in the similarity in- dices between treatment and control; for kemasol was 0.86 and 0.64, for caple 2 was 0.61 and 0.55 and for supermax was 0.64 and 0.86. LC25 of supermax did not cause any mortality to daphnia after 6 hr. but, LC50 and LC90 caused lower mortality after 6 hr. kemasol caused 100% mortality after 4 hr at LC50 and 2 hr in LC90. caple 2 caused 50% mortality of daphnia after 5 hr at LC25 and 100% mortality after 30 minutes in LC50 and LC90.

Semifield trials to control biomphalaria Alexandrina by different modes of exposure to certain plant and chemical molluscicides

Semi-field trials were carried out in Snail Research Station under simulated natural conditions to evaluate different modes of exposure to Anagallis arvensis and Calendula micrantha as plant molluscicides and bayluscide and copper sulphate as chemical molluscicides. Firstly, B. alexandrina were exposed to the tested molluscicides alone and in addition to two densities of aquatic plants. No apparent effect of aquatic plants on the activity of both plant and chemical molluscicides, this may be due that the two densities of the aquatic plants used were insufficient to interfere with the molluscicides action. Secondly, snails were pre-exposed to three sub-lethal concentrations of the plant molluscicides for 24h then to three concentrations of the chemical molluscicides and vice versa. The results indicate that the pre-exposure increases the snail mortality significantly in all treatments of bayluscide and A. arvensis [except in the highest concentration when the snails firstly exposed to bayluscide then to A. arvensis, where the two compared treatment showed 100%] and in all treatments of bayluscide and C. micrantha. Also, in one treatment of copper sulphate and A. arvensis [in the highest concentration when the snails firstly exposed to A. arvensis then to copper sulphate] and in three treatments of copper sulphate and C. micrantha, [in least and moderate concentrations when snails firstly exposed to C. micrantha then to copper sulphate and in the highest concentration when snails firstly exposed to copper sulphate then to C. micrantha]. Thirdly, snails were exposed to mixtures of six different ratios of hayluscide and each of A. arvensiS and C. micrantha. The results indicated that the snail mortality increased significantly only in the first treatient of bayluscide and A. arvensis mixtures and in treatment number 6 of bayluscide and C. micrantha

Effect of certain salts on biomphalaria Alexandria snail and their susceptibility to schistosoma mansoni infection

The effect of magnesium sulphate, calcium sulphate, manganese sulphate, sodium chloride and potassium chloride, on survival of B.alexandrina snails and their susceptibility to S.mansoni infection was evaluated. It was found that no snail was infected among survived ones in groups maintained continuously for 14 weeks post miracidial exposure at the experimental salts. However, snails in groups that were maintained at the experimental salts for 24 hours [during miracidial exposure] and kept after that in clean water were susceptible to infection at varying degrees. Although miracidia exposed to the experimental salts were alive after 2 hours, complete death was recorded after 24 hours of exposure to 200 ppm MnSO[4] [Mn = 65 ppm] and 1000 ppm from the other experimental salts The present work showed that MnSO[4] was more toxic to B. alexandrina snails than MgSO[4] and CaSO[4] either pre-or post exposure to S.mansoni miracidia. The suppressive effect of high calcium ions on cercarial production was supported by absence of infection among snails subjected to 2500 ppm CaSO[4] [Ca=581.3 ppm]. Moreover, increasing NaCl concentration from 1000 ppm to 2000 ppm [Na = 393.2, and 786.4 ppm] during snails exposure to miracidia caused more reduction in their cercarial output

Effect of UV-irradiation, gamma irradiation and praziquantel on infected biomphalaria alexandrina snails

Schistosomiasis control represent the main target of many research programs allover the world. Effect of physical [UV- and gamma irradiation] as well as chemical [PZQ] treatments on infected laboratory bred Biomphalaria alexandrina snails was studied. Gamma irradiation and PZQ treatment induced high rate of mortality than UV-irradiated and non treated control snails. The cercarial production was severely reduced as a result of UV-, gamma-irradiation and PZQ treatment. Pre-patent period was significantly increased in gamma-irradiated and PZQ-treated groups than UV-irradiated and control groups. Gamma irradiation and PZQ treatment showed severe effects on hermaphrodite gland and cercariae. Trials of experimental infection in Swiss albino mice revealed that low rate of infection [9.7% and 1.3%] was induced by cercarial shedding from UV-irradiated and PZQ- treated snails, respectively. Whereas, cercarial production of gamma- irradiated snails failed to induce infection in Swiss mice