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
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.