Family differences in success of triploid induction and effects of triploidy on fecundity of catarina scallop (Argopecten ventricosus)
2001
Mass induction of triploidy in the catarina scallop (Argopecten ventricosus) results in low success in the percentage of triploids produced. To understand whether this is a treatment effect affecting all eggs equally, families were individually induced to triploidy with cytochalasin-B (CB), comparing their survival from egg to D-larvae and spat, and the percent of triploidy within families. Differences in percent triploidy success were evident between families, obtaining some with no triploids, and some with high triploidy. Among the possible causes for these differences are quality of eggs, different developmental rates, and differences in susceptibility to the treatment (CB or DMSO) itself. Regardless of those differences, overall triploidy production was increased by inducing individually eggs of each scallop rather than in mixed egg batches. In the first experiment, it was improved by 17%, and in the second experiment by 42%, as indicated by the weighted mean of triploids among the families, and when compared with previous results with this same species, where triploidy success was 58%. In a second experiment with three different families, the growth and fecundity of triploid and diploid catarina scallops were evaluated. The growth superiority of triploids was confirmed. The results indicated that triploid catarina scallops had a significantly reduced fecundity when compared with diploid scallops. The reduced fecundity appears to be mostly of a random nature, possibly associated with a reduced capability to produce balanced gametes. Whereas the successful production of tetraploid catarina scallop from fertile triploid scallops is in principle possible, the low number of eggs shed by triploid catarina scallops could diminish that success rate, even more if single triploid females are required to optimize tetraploid induction.
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