非洲大蝸牛及其捕食性天敵

Abstract

非洲大蝸牛(Achatina fulica Bowd.)原產東非，十九世紀初經由印度洋分布及太平洋島嶼。於民國22年自新加坡引進本省，後即廣布於全省各地，成為本省農林作物之害蝸。該蝸卵孵化為幼蝸後經8~9個月即為成蝸，成蝸每年產卵3~6次，每次產卵200~500粒，壽命約2~3年。成蝸與幼蝸同具休眠及冬眠習性。本所為進行其生物防治研究，於民國48年及50年從夏威夷引進兩種肉食性蝸牛，即玫瑰蝸牛(Euglandina rosea Ferus., Oleacinidae)與嘉納蝸牛(Gonaxis quadrilateralis Prest., Streptaxidae)。此二種肉食性蝸牛均能捕食非蝸且能適應本省氣候，而嘉納蝸之適應力較強。非蝸之本省天敵本文亦有述及。 The giant African snail, Achatina fulica Bowdich, is a native snail of east Africa. It began its march from Africa to eastwards some 170 years ago, invading India, Indo— Malaya and then the Pacific. It was introduced from Singapore to Taiwan in 1932 and 1933 by a Japanese doctor, Kumaichi Shimojo for the purpose of using as food for human and poultry. Afterward, the snail rapidly spread throughout this island and devoured horticultural and agricultural crops. Its large size, diversified food habits, high reproductive ability and being hermaphroditic are all the causes for being a serious pest in Taiwan as well as in the other Southeast Asian countries. The snail matured within 9 months after hatching and could live for 2 to 3 years. It deposited 3 to 6 batches of eggs a year and 200 to 600 eggs each. The phenomena of estivation and hibernation is the physiological faculty of being able to survive prolonged periods withuot food or water supplied. For the biological control of Achatina snail in Taiwan, two predaceous snails, Euglandina rosea Ferus. (Oleacinidae) and Gonaxis quadrilateralis Prest. (Streptaxidae), were introduced from Hawaii by the authors in 1959 and 1961, respectively. The adult of Euglandina snail having spindle-shaped and dextral shell, about 3~6 x 2 cm in size, 7 whorls with deep suture, pink color, surface polished with numerous distinct, regular and longitudinal lines of growth; body dark grey to black except ventral side whitish. It matured within 4 to 8 months after hatching, depositing 100 to 200 eggs in 7 to 8 times during its life with 20 to 30 eggs in each oviposition. This snail could live for 1 to 3 years under Taipei climatic conditions. The adult of Gonaxis snail having spindle-shaped and dextral shell, about 2.7 x 2.0 cm in size; with beautiful orange antennae and light testaceous body color except ventral side yellowish grey. It matured within 4 to 6 months after hatching and could live for 1 to 3 years. About 120 eggs were deposited during its life. Gonaxis snail seems to be an effective predator for controling Achatina snail as observed in Taipei laboratory. It had successfully established in Chiayi during the liberations in 1967. The native predators of A. fulica have also been surveyed during our studies.