Management Information
Molluscs are one of the most intractable of pests once established. As there is a risk of Achatina fulica being spread via trade routes there is potential to prevent its spread via international quarantine and surveillance activities. The snail has been intercepted widely by quarantine officials (Moore 2005), including in "empty" containers on a vessel travelling from Pagopago, American Samoa, to New Zealand. This was despite certificates indicating they were free of Achatina fulica (News from MAF 2005).
Initial invasions of A. fulica have been eradicated from a few locations, notably Florida (USA) and Queensland (Australia). Control costs can range from $US60,000 dollars for a 7-month procedure, to over $US700,000 dollars for the eradication in Florida (Muniappan et al. 1986, Smith and Fowler 2003). Attempts to eradicate Achatina fulica in Queensland (Australia) and in three states in the USA have all involved hand collection of animals, followed by subsequent destruction (Mead 1979). However, the most pragmatic approach to control of terrestrial molluscs is the use of pesticides. Please see section 2.1.3 of Barker and Watts (2002) for comprehensive information on the application of pesticides (molluscicides) to control of terrestrial mollusc pests.
Location Specific Management InformationCalifornia (United States (USA))
The giant African land snail has been eradicated from California where it was present in a localised area in some thousands (Animal and Plant Health Inspection Service 2005) Florida (USA) (United States (USA))
The eradication of the A. fulica occurred after it had been established for five years and the cost was over US$ 1 million (Animal and Plant Inspection Service 2005). If the snail had been left unchecked the estimated annual loss to Florida would be US$ 11 million. The Florida eradication employed both handpicking of snails with the use of granulated chemical bait. Frequent foot by square foot surveys were conducted in teh area and over 400 properties were quarantined. Carbaryl drenches were also included (Simberloff 1997, in Cooling 2005). The campaign invovled thousands of hours of labout and is believed to have taken 2 to 3 years before all major infestation sites in Miami were discovered and reported (Mead 1979, in Cooling 2005). Hawaii (United States (USA))
Localised eradication on some islands of Hawaii appears to have been successful (Mead 1979). New Caledonia (Nouvelle Calédonie)
In 1976 a ten day campaign was run in which snails were collected around Noumea on a large scale involving members of the public (who were paid for snails collected) approximately 800 000 snails were collected. While these efforts did not eradicate the species it was sufficient to relieve the pressure on native species (CTRDP de Nouvelle Caledonie, date unknown). Attempted control methods include: biological controls (Euglandina rosea, Gonaxis quadrilateralis and G. kibweziensis), physical and chemical protection methods, educational programmes, the planting of resistant yam varieties and the application of salt, ash, oil or water in ditches around crops (J. Manaute, pers. comm., in Cooling 2005). New Caledonia (Nouvelle Calédonie) 
During the dramatic population explosion that followed [its introduction] (Tillier, 1982), biological control was tried using a model that had been applied elsewhere in the Pacific. Two species of predatory snails, Euglandina rosea (originating in Central America) and Gonaxis quadrilateralis (originating in East Africa), were introduced intentionally from Guam in 1974. Euglandina established locally but is not invasive, but Gonaxis did not acclimatize (Gargominy & Bouchet, 1996) (from Gargominy et al . 1996). New Zealand
On-going control is costly. Risk management and effects mitigation should prioritise prevention, followed by interception and treatment, early detection and rapid eradication and control efforts should aim to minimise adverse effects on native ecosystems, economic activities and public health. Prohibition of the organism and measures to support this are the first step in preventing the A. fulica from establishing in New Zealand. There is a huge risk of A. fulica being spread and introduced into new locations via trade routes. The snails ability to store sperm is a distinct advantage and could enable a founding population to form from just one individual. The majority of interceptions of A. fulica at ports of entry into Australia and New Zealand have been associated with containers. Most of the snails found were located outside of the containers. Of New Zealand's seaports Auckland had the highest number of containers landed and the most found with the snail, followed by Mt Maunganui. The large majority of giant African snail items brought into New Zealand via passengers and their luggage are declared as ornamental shells.
The Giant African Snail has been classified as an unwanted species in NZ since the Animals Act 1967 and remains classified as such under its replacement the Biosecurity Act. Several international strategies such as the World Conservation Unions Strategy on Invasive Species and the Regional Invasive Species Strategy of the South Pacific Regional Environmental Programme have also addressed the issue of the spread of A. fulica in the region. Biosecurity NZ has identified the following Pacific Island countries as high risk sources of A. fulica: Wallis and Fortuna Islands, Papau New Guinea and Vanuatu (areas where the snail has been historically intercepted from).
To improve the inspection system in New Zealand it has been suggested that these additional countries be added to the high risk status/category: American Samoa, French Polynesia, New Caledonia, Western Samoa, Philippines, Indonesia, Malaysia, Singapore, Bangladesh and South Africa. Supportive measures could include public education, access to information and penalty information, offshore certification to confirm container cleanliness and international harmonisation of biosecurity standards for containers.
New Zealand has a low level of suitability in terms of ecological requirements of the snail, primarily due to the relatively cold winter temperatures, however studies show they may survive in lower temperatures and global warming increases the likelihood of their establishment. The use of a geographic information software package (ArcMap) (based on the factors that limit the growth of A. fulica (moisture levels, temperature and land-cover type)) showed the northern and coastal regions of the North Island are the most likely areas to be colonised successfully by the giant African land snail (Cooling 2005).
Metaldehyde, methiocarb, thidicarb and iron chelate are all registered for use in New Zealand. However, indigenous New Zealand molluscs may be at particular risk to chemical control via baiting. DOC (2002) believe it is likely that Placostylus, Succinea and Archeai and some members of Charpoidae and Puntidae would be likely to eat the baits. Iron chelates could also affect some molluscs as well as isopods, crustacea and arachnida.
Much effort and money can be spent on control and eradication of the snail by commercial businesses, private individuals and the Government. The use of biological control agents is risky and has produced a number of undesirable effects overseas including the extinction of native molluscs. Chemical controls have the potential to affect native species, particularly native molluscs and are unpopular with the public. Vanuatu
Small populations of A. fulica have been eradicated from Fiji, Western Samoa, Vanuatu and Wake Island (Raut and Barker 2002). Wake Island (Eneen-Kio) (United States Minor Outlying Islands)
Small populations of A. fulica have been eradicated from Fiji, Western Samoa, Vanuatu and Wake Island (Raut and Barker 2002, in Cooling 2005).
Management Resources/Links
2. Civeyrel, L. and Simberloff, D. 1996. A tale of two snails: is the cure worse than the disease? Biodiversity and Conservation 5: 1231-1252.
Summary: A discussion of the introduction of predatory snails (notably Euglandina rosea), in putative attempts to control A. fulica. The devastating consequences on native land snail diversity, especially in the islands of the Pacific. 3. Cooling, V. 2005. Risk Assessment of the Giant African Snail (Achatina fulica) Bowdich in New Zealand. LPSC 7700 Integrative Report. Unitec New Zealand (Unpublished Report) 5. Cowie, R. H. 2001. Can snails ever be effective and safe biocontrol agents?. International Journal of Pest Management 47: 23-40.
Summary: Discusses the use of land and freshwater snails as biological control agents against other snails and against aquatic weeds. Recommends snails not be used for biocontrol. 6. Mead, A. R. 1961. The giant African snail: a problem in economic malacology. Chicago, University of Chicago Press.
Summary: Major treatise on the worldwide spread of A. fulica, its impacts, and management. 7. Mead, A. R. 1979. Pulmonates volume 2B. Economic malacology with particular reference to Achatina fulica. London, Academic Press.
Summary: Update of Mead 1961. 9. Walker, K. 2006. Giant African Snail (Achatina fulica) Pest and Diseases Image Library. Updated on 13/02/2006 9:44:47 AM.
Summary: PaDIL (Pests and Diseases Image Library) is a Commonwealth Government initiative, developed and built by Museum Victoria's Online Publishing Team, with support provided by DAFF (Department of Agriculture, Fisheries and Forestry) and PHA (Plant Health Australia), a non-profit public company. Project partners also include Museum Victoria, the Western Australian Department of Agriculture and the Queensland University of Technology.
The aim of the project is: 1) Production of high quality images showing primarily exotic targeted organisms of plant health concern to Australia. 2) Assist with plant health diagnostics in all areas, from initial to high level. 3) Capacity building for diagnostics in plant health, including linkage developments between training and research organisations. 4) Create and use educational tools for training undergraduates/postgraduates. 5) Engender public awareness about plant health concerns in Australia.
PaDIL is available from : http://www.padil.gov.au/aboutOverview.aspx, this page is available from: http://www.padil.gov.au/viewPestDiagnosticImages.aspx?id=228 [Accessed 6 October 2006]
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