A TALE OF 2 SNAILS - IS THE CURE WORSE THAN THE DISEASE

The giant African snail, Achatina fulica, has been introduced to many parts of Asia as well as to numerous islands in the Indian and Pacific Ocean, and has recently reached the West Indies. It has been widely d ecried as a disaster to agricultural economies and a threat to human h ealth, leading to a clamor for the introduction of biological control agents. In fact, the lasting impact on agriculture may not be severe, and the human health risk is probably minor. This snail can be an aest hetic atrocity and a nuisance in other ways, however. Wherever A. fuli ca has achieved high densities, it has subsequently undergone a striki ng decline. Although this decline has been attributed to introduced pr edators, there is little evidence for this hypothesis; instead, epizoo tic disease seems to be at least part of the cause. However, the intro duced predators, especially a New World snail, Euglandina rosea, have wrought havoc with the native land snails of many islands. They have a lready caused many extinctions and will almost certainly cause others. This predator was introduced by government agencies in many areas des pite warnings from competent biologists that the effects could be disa strous. Pressures for such actions may become overwhelming in the face of a highly visible invasion, despite policies that should mandate ex treme caution.