March 2003. The Giant African snail (Achatina fulica) was first found in St Lucia, West Indies, in July 2000. Although it has been found on many crops, it is not yet a major agricultural pest. It feeds mainly on decaying organic matter (plant or animal). It also has destroyed a few young papaya trees.
The Crop Protection and Quarantine Unit are about to embark on an eradication attempt. This will comprise two components:
- Public Awareness (starting immediately) and
- Eradication (starting with the rainy season in June), comprising surveys, collections and the application of molluscicides.
Advise was sought as to whether this was indeed possible, and any success (or failures) stories that St Lucia can learn from.
Information was given on an eradication programme that was carried out at Gordonvale, Australia. The campaign mostly involved baiting. Kosrae, Federated States of Micronesia, was also interested in eradication in Gordonvale. GAS was accidentally introduced there a few years’ back (1995-1996). It was pointed out that a key feature of the GAS infestation at Gordonvale was that the area, which was subjected to metaldehyde baiting, was surrounded by cane fields which seemed to provide an inhospitable barrier against the snails’ dispersal. No live snails were found eight months after treatment commenced, but it was the decision of a Commonwealth/States Consultative Committee responsible for the eradication programme to wait for three years after the last detection of any live snails to claim successful eradication.
The snail is also a recent introduction to Sikkim, eastern Himalayas, where it is attacking pulses and vegetables. It is the women’s livelihoods that have been most affected, as their vegetable crops have been destroyed by the snails, and they have little to sell in the market. An awareness programme was being organised.Metaldehyde is effective, but expensive. Mobilising the community to collect the snails in the early mornign is likely to be a more sustainable method of control.
Additionally, information was asked about the rat lung worm:
- how is it possible to tell if the snails are infected
- can the worm survive in the slime of the snail.
The Secretariat of the Pacific Community (previously South Pacific Commission) or SPC for short has put out a number of Pest Advisory Leaflets in colour on various pests including Achatina fulica (Giant African Snail). These are available as pdf files and can be viewed from our website: www.spc.int/pps/. SPC is using a 7.5% Metaldehyde bait, Trails End, which is supplied by a company in USA (AMNAC Chemical Corporation, 4100 Washington. The German Plant Protection Project in Tonga made once a GAS bait from
concrete blocks mixed with Metaldehyde. In addition, a 18g/kg Metaldehyde bait “Slug & Snail” was used for the GAS eradication programme that began in Samoa 5 years ago (1998). Good data was collected on the product.
Another bait can be made using wheat bran, stale beer with 1% iron phosphate made into pellets and placed safely where ony snails can reach it. Usually, they die after 3-4 days from feeding on it.
Caffeine has proven successful both as a repellant and as a biocide. Dr Robert Hollingsworth, USDA PBARC researched this and can certainly give more information. Spent coffee grounds in potting soil worked well under nursery conditions where Achatina fulica was abundant in Samoa, and could possibly work in small garden settings, especially in dryer conditions. For largescale agriculture consider integrating domestic ducks into the system. There are numerous reports of them being quite effective against both terrestrial and aquatic slugs and snails and they could provide added income through meat and eggs.
There are images on Ecoport: http://www.ecoport.org/EP.exe$PictShow.
Members reiterated that Euglandina and other predatory snails should not be introduced for the control of GAS, as has been done in some countries with detrimental effects on the local ecology. It is one of the most ecologically damaging organisms in the Pacific. This predatory snail was introduced into Hawaii and soon caused the extinction of dozens of species of endemic snails, which they eat as snacks when they can’t find African snails. It was recently introduced to American Samoa, and it is now hard to find any native snails on Tutuila and, despite all the notariety on its devastating effects on the mollusc fauna, it was recently introduced to Ta’u, where the snail fauna is doomed. See also: http://www.google.com/search?safe=on&q=euglandina+extinction
The Global Invasive Species Database has Euglandina listed as one of the world’s worst invaders:
The following reference is online: Albert R Mead (1961) The Giant African snail: A problem in economic malacology. University of Chicago Press. Chicago. 257 pp. illus.: www.hear.org/books/. A second book by the same author is: Mead AR (1979) Economic malacology, with particular reference to Achatina fulica. Pulmonates. Volume 2B. Academic Press. London, U.K. 150 pp.
Another useful review is: Raut SK, Barker GM (2002) Achatina fulica Bowdich and other Achatinidae as pests in tropical agriculture. In: Barker GM (ed.) Molluscs as Crop Pests. pp. 55-114. Wallingford, CABI Publishing. (ISBN 0 85199 320 6). This review has 20 pages of references.