Study of the susceptibility of Biomphalaria alexandrina collected from five different localities in Egypt to infection with local strain of Schistosoma mansoni

Biomphalaria Alexandrina snails were collected from five different localities, and their progenies through successive generations, were compared with respect to their susceptibility to infection with the local strain of Schistosoma mansoni. There was difference in the susceptibility between snails from different localities and this susceptibility increased through the successive generations. Progenies from negative parents were less susceptible and the resistance increased through negative generation whereas those from positive parents were more susceptible and the susceptibility increased through the positive generations. Results from studying the inheritance of susceptibility among progenies, produced individually from the same snail demonstrated some snails with great diversity of genetic pattern of susceptibility among progenies. Some snails presented with progenies testing 0% susceptibility and others with progenies testing 100% susceptibility. These snails could be the beginning of true breeding refractory or susceptible stocks. Field snails and their progenies have been reared individually to reproduce only with self-fertilization. Several morphologidal differences in pigmentation have appeared which would be useful in the genetic studies on B. Alexandrina

Influence of some natural and synthetic substances on certain fresh water organsisms and the snail vectors of Schistosomiasis and Fascioliasis

The effect of plants Anagallis arvensis, Calendula micrantha and Ambrosia maritima and the synthetic chemical molluscicides bayluscide and copper sulphate on survivorship, egg production of the snail vectors of schistosomiasis [Biomphalaria alexandrina] and fascioliasis [Lymnaea natalensis] and on some fresh water organisms were studied. Anagallis arvensis and Calendula micrantha showed good molluscicidal action against B. alexandrina and L. natalensis where LC90 values were 88 and 93 ppm, respectively, for A. arvensis and 135 and 100 ppm, respectively, for Calendula micrantha. The cumulative mortality of B. alexandrina [70%] was considerably high after 4 weeks of continuous exposure to A. arvensis. Complete inhibition of egg production was obtained for B. alexandrina after 2 weeks of exposure to low concentration of C. micrantha, bayluscide and copper sulphate. A. arvensis increased the maximum standing crops of algal biomass of Sirogyra [1.1358 g] and daily specific growth rate [0.0586 g.], while the control was 1.0106 g. and 0.0503 g., respectively. A low toxic effect on Daphnia pula was obtained under the effect of Anagul1is arvensis [5% mortality] and calendula micrantha [25% mortality] compared with synthetic molluscicides suggesting the use of the tested plants as molluscicides

Effect of copper sulphate, certain plants and adjuvants on the snails Biomphalaria alexandrina and Lymnae natalensis and on the zooplankton [Daphnia pulex]

The snails Biomphalaria alexandrina and Lymnaea natalensis were exposed to 1/10 LC50 of copper sulphate or of the plants Anagallis arvensis, Calendula micrantha and Ambrosia maritima. The snails were exposed firstly to copper sulphate then to each of the tested plants and vice-versa. The results showed that the pre-exposure of snails to A. arvensis and C. micrantha plants increased the molluscicidal action of copper sulphate against B. alexandrina and L. natalensis where it caused an additive effect. The pre-exposure to A. maritima caused different effects with copper sulphate, where it showed antagonistic effect on B. alexandrina and additive effect on L. natalensis snails. The pre-exposure of snails to copper sulphate increased the molluscicidal action of the tested plants against B. alexandrina and L. natalensis where it caused synergistic effect in case of Anagallis arvensis and Calendula micrantha against L. natalensis and additive effect in the rest of the treatments. Mixing of copper sulphate with each of the tested plants at different ratios caused antagonism in the molluscicidal activity of copper sulphate against B. alexandrina and L. natalensis snails. The addition of each of the following adjuvants; mono-ethylene glycol mono-oleate, mono-ethylene glycol di-oleate, potassium di-hydrogen phosphate and KZ mineral oil to copper sulphate increased the molluscicidal activity of copper sulphate against B. alexandrina, where it caused synergistic effect. In case of L. natalensis, mono-ethylene glycol mono-oleate and mono-ethylene glycol di-oleate caused an additive effect; while, potassium di-hydrogen phosphate and KZ mineral oil induced antagonistic effect. The result of examination of the toxic effect of copper sulphate in combination with each of the tested adjuvant against Daphnia pulex indicated that the treatment of copper sulphate and mono-ethylene glycol di-oleate increases the molluscicidal activity of copper sulphate and at the same time reduces its toxic effect against non-target organisms [Daphnia] and is the best for application

Difference in the susceptibilty to certain molluscicides and Schistosoma mansoni infection of three forms Egyptian Biomphalaria glabrata

The first generation of three morphologically different forms of B. glabrata collected from Giza was compared for LC50 values susceptibility to bayluscide and copper sulfate [chemical molluscicides], Anagallis arvensis and Calendula micrantha [plant molluscicides] as well as to Schistosoma mansoni infection. Form 2 as juvenile and adult was less sensitive to C. Micrantha and A. arvensis. Form 3 as juvenile and form 1 as adult were least sensitive to CuSO4. Approximately, the same susceptibility to bayluscide was observed in the three forms, either as juvenile or adult. The sublethal concentrations of the molluscicides on the three forms of B. glabrata showed no significant difference in the growth or survival rate in-between. Form 2 was significantly higher in the egg-laying capacity. The total protein concentration was not affected, except in certain cases, where the increase was primarily due to the increase in the globulin concentrations which was observed with the marked increase observed in the urea concentration and the marked increase or inhibition in the activity of either aspartate aminotransferase [AST] or alanine aminotransferase [ALT]. The digestive gland of the three forms of B. glabrata showed a low susceptibility to infection with the local strain of S. mansoni