Size and age at first copulation and spawning of the apple snail, Pomacea canaliculata (Gastropoda: Ampullariidae).
The size and age at first copulation and spawning of the apple snail, P. canaliculata collected from rice fields in Kumamoto, Japan in September and October 2000 were determined at three food levels under laboratory conditions (14L:10D; 25°C). Males fed at a low food level started copulation at smaller sizes than males at higher food levels. However, age at first copulation was similar among snails at all food levels. The food level appeared to affect the penis sheath length at maturity, although the difference did not reach a statistically significant level. Females fed at the low food level delayed both first copulation and spawning longer than those at higher food levels. Consequently, their sizes at first copulation and spawning were smaller. The albumen gland of poorly fed snails was smaller at first copulation but comparable at maturity. The adaptive significance of these patterns in sexual maturity and their possible implications for the integrated management of this snail are discussed.