Estimating the overwintering mortality of the apple snail, Pomacea canaliculata (Lamarck) (Gastropoda : Ampullariidae) in a paddy field of southern Japan using temperature data.

Overwintering mortality of the apple snail, Pomacea canaliculata was invest igated in a paddy field of Southern Japan for seven consecutive years. Fiel d data and laboratory experiments revealed snails larger than 6.0 mm exhibi ted higher cold tolerance than small snails. Seven-years of field data show ed that a linear regression explained a close relationship between the over -wintering mortality of snails larger than 6.0 nim and the cumulative low t emperature calculated as the subtraction of the hourly temperature from 10 degreesC (CLT). A high correlation was also observed between overwintering mortality of snails and the mean temperature between December and February. Thus, temperature data seems to be practical and effective in estimating m ortality of field snails during the winter.