A. fulica is distinctive in appearance and is readily identified by its large size and relatively long, narrow, conical shell. Reaching a length of up to 20 cm, the shell is more commonly in the size range 5-10 cm. The colour can be variable but is most commonly light brown, with alternating brown and cream bands on young snails and the upper whorls of larger specimens. The coloration becomes lighter towards the tip of the shell, which is almost white. There are from seven to nine spirally striate whorls with moderately impressed sutures. The shell aperture is ovate-lunate to round-lunate with a sharp, unreflected outer lip. The mantle is dark brown with rubbery skin. There are two pairs of tentacles on the head: a short lower pair and a large upper pair with round eyes situated at the tip. The mouth has a horned mandible, and a radula containing about 142 rows of teeth, with 129 teeth per row (Schotman, 1989;Salgado, 2010). Eggs are spherical to ellipsoidal in shape (4.5-5.5 mm in diameter) and are yellow to cream in colour.
A. fulica is a large and conspicuous crop pest which hides during the day. Surveys are best carried out at night using a flashlight. It is easily seen, and attacked plants exhibit extensive rasping and defoliation. Weight of numbers can break the stems of some species. Its presence can also be detected by signs of ribbon-like excrement, and slime trails on plants and buildings.
Related invasive species
- Achatina fulica
Related Farm Practice
- Soil
- Pests
- Light
- Cuttings
- Feeding
- Plant communities
- Retention
- Removal
- Damage
- Development
The giant African land snail A. fulica is a fast-growing polyphagous plant pest that has been introduced from its native range in East Africa to many parts of the world as a commercial food source (for humans, fish and livestock) and as a novelty pet. It easily becomes attached to any means of transport or machinery at any developmental stage, is able to go into a state of aestivation in cooler conditions and so is readily transportable over distances. Once escaped it has managed to establish itself and reproduce prodigiously in tropical and some temperate locations. As a result, A. fulica has been classified as one of the world's top 100 invasive alien species by The World Conservation Union, IUCN (ISSG, 2003).
In garden plants and ornamentals of a number of varieties, and vegetables, all stages of development are eaten, leading to severe damage in those species that are most often attacked. However, cuttings and seedlings are the preferred food items, even of plants such as Artocarpus which are not attacked in the mature state. In these plants damage is caused by complete consumption or removal of bark. Young snails up to about 4 months feed almost exclusively on young shoots and succulent leaves. The papaya is one of the main fruits which is seriously damaged by A. fulica, largely as a result of its preference for fallen and decaying fruit.
In plants such as rice, which are not targets of A. fulica, sometimes sheer weight of numbers can result in broken stems. In general, physical destruction to the cover crop results in secondary damage to the main crop, which relies on the cover crop for manure, shade, soil and moisture retention and/or nitrogen restoration. This in turn can result in a reduction in the available nitrogen in the soil and consequently marked erosion in steeper areas.
A. fulica is a polyphagous pest. Its preferred food is decayed vegetation and animal matter, lichens, algae and fungi. However, the potential of the snail as a pest only became apparent after having been introduced around the world into new environments (Rees, 1950). It has been recorded on a large number of plants including most ornamentals, and vegetables and leguminous cover crops may also suffer extensively. The bark of relatively large trees such as citrus, papaya, rubber and cacao is subject to attack. There are reports of A. fulica feeding on hundreds of species of plants (Raut and Ghose, 1984;Raut and Barker, 2002). Thakur (1998) found that vegetables of the genus Brassica were the most preferred food item from a range of various food plants tested. However, the preference for particular plants at a particular locality is dependent primarily on the composition of the plant communities, with respect to both the species present and the age of the plants of the different species (Raut and Barker, 2002). Crops in the Poaceae family (sugarcane, maize, rice) suffer little or no damage from A. fulica.
Given the polyphagous nature of A. fulica any host list is unlikely to be comprehensive. Those plant hosts included in this datasheet have been found in literature searches and Venette and Larson (2004).