Life cycle of the South American apple snail Asolene platae (Caenogastropoda: Ampullariidae) under laboratory conditions

BURELA S; TIECHER M.J; MARTIN P.R.

JOURNAL OF MOLLUSCAN STUDIES

OXFORD UNIV PRESS

Lugar: Oxford; Año: 2016 vol. 82 p. 432 - 439

0260-1230

Reproductive mode, life cycle and fecundity are relevant to understand andpredict the spread and impacts of freshwater invasive mollusks. Ampullariids or apple snails have been intensively studied during the last decades due to the fast expansion around the world and the severe impacts of two species of Pomacea, a genus with a peculiar reproductive mode (aerial egg masses). We investigated the life cycle and fecundity of Asolene platae, an apple snail with a different reproductive mode (aquatic egg masses) from the Río de la Plata basin by following three cohorts from hatching to death under laboratory conditions. Growthof A. platae remained continuous during the four-year lifespan and the snailsreached 80% of their asymptotic size at an age of one year. In terms of the von Bertalanffy model females attain higher asymptotic sizes (26.02 to 25.72 mm) than males (23.01 to 24.89 mm) but males grow to their asymptotic sizes at slightlyhigher rates than the females (0.047 to 0.054 vs 0.050 to 0.057 week-1). Males matured at a smaller size (21.16 vs. 24.53 mm) and much earlier (55.02 vs. 84.88 weeks) than females. The survivorship curves showed 63% mortality during the first 2-8 weeks, an almost null mortality for two years and finally a steady decline in the number of survivors with at least 7% of the snails still alive after three years. The lifespan fecundity of females included 20.61 egg masses and 1429.9 eggs. The tertiary sex ratio of the three cohorts was balanced but varied from 0.25 to 0.76 among egg masses. Our laboratory data indicated that, in temperate environments, A. platae males would mature in their second summer and females during their second or third summer, and those survivors would reproduce again during the three following summers. Several attributes of the life cycle of A. platae (slow growth, high post-hatching mortality, late maturation and relatively low fecundity) indicate lower invasive potential and population resilience than that of invasive apple snails.