This study focuses on the possibility of experimental hybridization among host snail species forIntraspecific and interspecific crossbreedings among host species have been described in the literature since the 1950s. Paraense (1955) and Paraense and Deslandes (1955) performed experiments based on intra-and interspecific crossbreeding. The former, intraspecific crossbreeding, aimed to establish these species' reproductive preferences, while the latter focused on the possibility of interspecific crossbreeding between B. glabrata and B. tenagophila, which were located 315 km from each other. The authors observed in these respective experiments that cross-fecundation is preferential and that the crossbreeding proposed was not viable, reporting reproductive isolation between the species of Biomphalaria studied. Interspecific crossbreedings between geographically isolated species were described by Barbosa: B. alexandrina (Cairo, Egypt) and B. glabrata (Recife, Pernambuco, Brazil) in 1956; B. straminea (Pernambuco, Brazil) and B. peregrina (Ecuador); B. tenagophila (São Paulo, Brazil) and B. peregrina (Ecuador) (Barbosa et al. 1958). Formation of fertile hybrid offspring was observed in these crossbreedings. The same author in 1964 commented on the natural hybridization of B. glabrata and B. tenagophila, reporting intermediate forms, explained by the proximity of the respective populations. Later on, Barbosa (1973) observed this process of natural hybridization in the Northeast of Brazil, between B. glabrata and B. straminea. Breeding sites previously colonized exclusively by B. glabrata were replaced by B. straminea over the course of three years. During the process of competitive exclusion, mixed forms were found, possibly resulting from interspecific crossbreeding. Such intermediate forms were no longer found during later field studies, showing their inability to persist in nature. This study's objectives were to observe the possibility of experimental hybridization between host species for Schistosoma mansoni in Brazil and to study the reproductive capacity and subsequent morphological characterization of the hybrid forms.

The Euphobia milii var. hislopii latex has been tested in the control of schistosomiasis but its action in the locomotor activity of Biomphalaria glabrata is unknown. The objective of this work was to study the locomotor and reproductive behaviors of B. glabrata exposed to E. milii var. hislopii latex. For this, 96 snails were individually exposed to the latex (LC 50-0.53 mg / L) for 24 hours. The specimens were submitted to biomonitoring for image analysis to record the locomotor parameters at different times: before exposure (control), one day post exposure (group 1 d-p-e) and 30 days post exposure (group 30 d-p-e). The reproductive parameters were recorded weekly for 10 weeks. All locomotor activities of group 1 d-p-e decreased significantly. The egg/egg mass ratio decreased the week after exposure while there was an increase in the hatching rate. After 30 days, these reproductive parameters were similar to those observed in these same snails before exposure. However, the number of hatched snails declined after exposure until the end of the experiment. The influence of the latex in the parameters of B. glabrata added further evidence that this natural water-soluble product can be an important tool for the control of schistosomiasis.

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Schistosomiasis is a neglected tropical disease and affects over 200 million people worldwide. The snail Biomphalaria glabrata is one of the intermediate hosts of S. mansoni. The aim of this work was to verify the action of Euphorbia milii var. hislopii latex in the hemocytes profile and histopathology of B. glabrata infected by S. mansoni.Uninfected and infected snails were exposed to sublethal concentration of E. milii latex for 24 hours (1.0 mg/L). The survival rate was 88.5% for the uninfected snails and 66.6% for the infected and exposed snails. In the snails infected by S. mansoni, the exposure to E. milii latex promoted proliferation of hemocytes in the tentacles, mantle, digestive gland and kidney. In the digestive gland and the kidney, granulomatous reactions occurred around the sporocysts and caused their destruction. The number of circulating hemocytes from the group infected and exposed to E. milii latex was significantly higher than in the other groups. Three types of hemocytes were found: hyalinocytes, granulocytes and blast-like cells. We conclude that the E. milii latex influenced the cellular immune response of the susceptible B. glabrata strain to infection by S. mansoni, promoting the destruction of parasites.

Background: Schistosomiasis is a neglected tropical disease and affects over 200 million people worldwide. The snail Biomphalaria glabrata is one of the intermediate hosts of S. mansoni . The aim of this work was to verify the action of Euphorbia milii var. hislopii latex in the hemocytes profile and histopathology of B. glabrata infected by S. mansoni .Methods: Uninfected and infected snails were exposed to sublethal concentrations of E. milii latex for 24 hours (1.0 mg/l less than the LC 50 ) and after this time were analysed.Results: The survival rate was 88.5% for the uninfected snails and 66.6% for the infected and exposed snails. In the snails infected by S. mansoni , the exposure to E. milii latex promoted proliferation of hemocytes in the tentacles, mantle, digestive gland, kidney and ovotestis. In the digestive gland and the kidney, granulomatous reactions occurred around the sporocysts and caused their destruction. Proliferation of hemocytes in the kidney and digestive gland and edema in the mantle area were also observed in the uninfected and exposed snails. The number of circulating hemocytes from the group infected and exposed to E. milii latex was significantly higher than in the other groups. Three types of hemocytes were found: hyalinocytes, granulocytes and blast-like cells, and in all the groups the proportion of hyalinocytes was higher than the other types. There was no significant difference among the cell types and the different groups analyzed. Conclusions: We conclude that the sublethal concentration of E. milii latex influenced the cellular immune response of the susceptible B. glabrata strain to infection by S. mansoni , promoting the destruction of parasites.