The golden apple snail in the rice fields of Asia

Rice fields in the Philippines devastated by the snail

The golden apple snail was introduced from Florida and Latin America to Taiwan (Province of China) and the Philippines in the early 1980s by private snail farmers hoping to reap big profits exporting snails to Europe. Easy to rear and fast breeding, the snail's high protein content also apparently made it an ideal supplement to the low-protein diet of the rural poor. Unfortunately, the snails were not a success with consumers, and although they were initially expensive, their market value soon plummeted.

The escaped and discarded snails quickly spread through waterways and irrigation canals. When they reached the rice fields they found an ideal habitat, feeding by night and at dawn on young succulent plants such as newly transplanted rice crops and weeds. With only a few natural enemies to constrain them, the snails rapidly developed into a serious pest in many areas of cultivated rice land in Asia. Their fast growth and reproduction - females lay egg masses of up to 500 eggs once a week - leads to population levels that can destroy entire rice crops.


Golden apple snail egg masses: newly laid (right) and near to hatching (left)

Golden apple snails feeding on azolla


Photos by Dr M. Halwart (by kind permission of Margraf Verlag, Weikersheim, Germany)

30 April 1998

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