Comparison of development and overwintering rates and feeding efficiency on rice seedlings among two invasive freshwater apple snails and their hybrid

Abstract

Since the 1980s, the freshwater apple snails, Pomacea canaliculata, Pomacea maculata, and their hybrid, have been introduced into a wide range of freshwater ecosystems in tropical to temperate regions. Although P. canaliculata has become established in temperate East Asia, P. maculata and the hybrid are rarely found in this region. To evaluate the risk of P. maculata and the hybrid particularly as rice pests in temperate regions, we compared growth rate, winter survival rate, and feeding efficiency on rice seedlings of these snails with P. canaliculata. When P. maculata and P. canaliculata hatchlings were reared under laboratory or field conditions, the adult P. maculata had larger shells than adult P. canaliculata. Neither P. maculata nor F1 hybrids could survive winter in a simulated drained paddy field, and only a few individuals of P. maculata and F1 hybrids overwintered successfully in freshwater. Pomacea maculata juveniles fed on rice seedlings at the highest rate at temperatures above 27°C. These results suggest that P. maculata becomes a serious rice pest in temperate region as P. canaliculata once it is introduced from warmer regions under global warming. Further biological examination of P. maculata is needed to evaluate the risk of this snail in detail.