Achatina fulica (Bowdich, 1822): A New Old Problem
by Jose Coltro
Many Florida residents remember the problem with Achatina fulica when it was introduced in this state. As an agricultural pest in Florida, the shell was eradicated (see Abbott, 1989, Compendium of Landshells, pg.78) in 1972. I have found specimens in Hawaii and American Samoa and I have received specimens from Philippines, Sri Lanka, Tahiti, etc. In Tutuila, American Samoa, I found only this species and none of the local species (Partula sp.). It seems that the Achatina destroy the native species not by preying upon them, but by competing for food. In some of those places the local authorities have introduced a very dangerous predator: Euglandina rosea (Ferussac, 1821), a Southeast U.S. species. As a very carnivorous species, it attacks not just the Achatina, but all the other species as well. Many species on the Pacific islands are endangered species: the Euglandina eats all of them.
In 1990 some members of our shell club, Conquiliologistas do Brasil, saw some live specimens of Achatina. These snails were part of an agricultural exhibition in a display about "escargot," Helix aspersa Muller, 1774 -- the commonest species used in French cuisine. The man who created the display told them that the shells were only for exhibition, not to sell. But a few weeks later we saw news in an agricultural magazine of this man showing his "escargot" farm with many Achatinas. We decided to send a letter to our governmental wildlife institution (Ibama) with many articles about the dangerous situation of introduction of this species here in Brasil. We never received a single answer.
Some months ago a small town at the Sao Paulo State, called Miracatu, had to ask for help to try to control an agricultural pest. A giant snail was destroying most of the crops around the town, eating large areas of lettuce, beans, corn, etc. Recently news reached us about another problem in one of our most popular beaches, Praia Grande: a giant snail invading houses. Guess which shell was the culprit in both situation? Achatina fulica, of course! In another four states, Rio de Janeiro, Minas Gerais, Parana and Santa Catarina, specimens are found in quantity.
Achatina fulica has no natural predator in Brasil and the shell competes with some local species, especially with the Megalobulimus group. Miracatu is on the border of our most important Atlantic tropical rain forest park, where it is possible to find over 25 different described species of Megalobulimidae and Strophocheilidae and many other new species. The reproduction of Megalobulimus isn't like the Achatina, and they will probably become extinct in many areas before the Government starts to control this pest.
Members of our club are trying to meet with people from our Government to alert them about the problem. It will be very hard to try to exterminate or even to control the Achatina population. The tropical forest is very dense and in many parts it is impossible to walk through. Most of our country is really mountainous and rugged terrain doesn't help any efforts to control this species. It will always be possible for some populations to exist, hidden in valleys in the forest, which can then spread out again. And yet the "escargot" people still breed this species. Without a law to banish the culture of this species from our country, we could have always accidental introductions and the problem will be here forever.