The extinction of endemic species by a program of biological control

Abstract

Land snails of the genus Partula, inhabiting the high islands of the Pacific Ocean, have provided exceptional opportunities for studies on the origin and differentiation of species. The endemic taxa of Moorea, in French Polynesia, have been particularly well studied. In an attempt to control the numbers of the giant African snail, Achatina fulica, which is an agricultural pest, a carnivorous snail, Euglandina rosea, has been introduced into Moorea. It is spreading across the island at the rate of about 1.2 km per year, eliminating the endemic Partula. One species is already extinct in the wild; and extrapolating the rate of spread of Euglandina, it is expected that all the remaining taxa will be eliminated by 1986-1987. Euglandina has been introduced into many other oceanic islands, and it appears that more than a hundred endemic species are at risk. These observations point to a serious danger in programs of "biological control."