The aim of the present work was to study parasitological, molecular, and genetic aspects in descendants of crossbreedings between a totally resistant
Biomphalaria tenagophila
strain (Taim, RS) and another one highly susceptible (Joinville, SC) to
Schistosoma mansoni
. Descendants F
1 and F
2 were submitted to
S. mansoni infection (LE strain). The susceptibility rates for individuals from Group F
1 were 0 to 0.6%, and from Group F
2 was 7.2%. The susceptible individuals from Group F
2 discharged a lower number of cercariae, when compared with the susceptible parental group, and in 2 out of 9 positive snails the cercarial elimination was discontinued. In order to identify genetic markers associated with resistance the genotype of parental snails and their offspring F
1 and F
2 were analyzed by means of the randomly amplified polymorphic DNA method. Nevertheless, it was not possible to detect any marker associated to resistance, but the results showed that in the mentioned species the resistance character is determined by two dominant genes.
