Effect of Basudin, Selecron and the phytoalkaloid Colchicine (pesticides) on biological and molecular parameters of Biomphalaria alexandrina snails

The results showed that survival rates of Biomphalaria alexandrina snails, reproductive potential and hatchability of eggs were evaluated post exposure to Basudin, Selecron and Colchicine. As well, DNA and RNA changes in the cells of ovotestis-digestive gland complex of treated snails were estimated. The current molluscicide Bayluscide was used as a reference compound.The pesticide Selecron proved to be more toxic to B. alexandrina snails than Basudin and Colchicine. Juvenile snails were dead post 3weeks of exposure to the sublethal concentration LC 0 of either Selecron or Basudin, while 26.75% of snails still alive at Bayluscide treatment. In addition, exposure of adult snails to LC 0 of Selecron for 24h/week for 4weeks markedly reduced their reproductive rate (R 0) by 89.9%. Moreover, snails' eggs failed to hatch post 24h of exposure to LC 90 of either Selecron, Basudin or Bayluscide. Electrophoretic analysis indicated a decrease in the molecular weight of intact DNA in the ovotestis-digestive gland complex of snails treated with 250ppm of Colchicine and LC 25 of Selecron, as it scored 1.2 and 76bp, respectively, compared to 166.46bp for control group, while the vice versa was recorded for RNA intensity. It was concluded that the tested pesticides have deleterious effects on snails' reproductive rate, their eggs and the intensities of DNA and RNA in their ovotestis-digestive gland complex. Therefore, it is expected that reaching of such pesticides to snails' habitats in water courses during plant pests control could minimize the population density of the snails intermediate hosts of schistosomiasis, hence probably interrupt and reduce the transmission of this parasite. © 2011 Elsevier Inc.