Giant African snail
Have you seen the giant African snail?
In Queensland, giant African snail is prohibited matter under the Biosecurity Act 2014. This means that it is an offence to deal with the pest.
Be on the lookout for giant African snail and report the pest immediately to Biosecurity Queensland on 13 25 23.
Early detection is vital.
Giant African snail (Achatina fulica) is one of the world's largest and most damaging land snail pests. It has spread quickly around the world by 'hitchhiking' to new locations on a range of cargo types, particularly on pallets, shipping containers and vehicles. If introduced to Australia, it has the potential to be a serious environmental and agricultural pest, capable of feeding on over 500 species of plants - a number of which are of commercial importance.
This snail does not occur in Australia. However, it is occasionally detected on imported shipping containers and materials. An outbreak of these snails occurred in Gordonvale, Queensland in 1977 and was subsequently eradicated. A more recent detection of a lone giant African snail was made on a property in the Currumbin Valley in 2004. A baiting program was established and extensive surveillance conducted in the surrounding area with no further detections made.
Originating in east Africa, giant African snails have spread to much of the Indo-Pacific region (bordering mainland and island areas of the Indian and Pacific Oceans) either by accidental means or purposeful introduction by humans as an alternative food source. These snails are very hardy and have the ability to enter a dormancy period, enabling them to survive for long periods without food. They also have a rapid reproductive rate allowing them to colonise new areas very quickly. Although the giant African snail is a tropical species, it can survive cold conditions, even snow, in its dormant state.
|What does it look like?|
The giant African snail is much larger than native Australian snails. Its shell ranges in size from 5-10 cm, but can measure up to 30 cm and weigh 1 kg. The shell is conical, tapering to a point as compared to a number of native snail species whose shells are mostly globular. The colour of the shell can vary, but is commonly brown with pale cream streaks.
Giant African snail eggs are laid in batches of 100-400 and are spherical to oval in shape, approximately 5 mm in diameter and cream to yellow in colour.
|Where does it occur?|
Giant African snails are usually active at night, emerging at dusk to feed in the open then returning to shelter at dawn. On wet days they will remain active during daylight.
They are commonly found under leaf litter, old roofing iron and timber, compost heaps, thickly grown ornamental shrubs and in crevices between rocks and tree roots. At night they will often be found on barriers such as fences and house walls.
During the Gordonvale outbreak, snails were commonly found during the day at the base of banana clumps, particularly on neglected plants where there was a large amount of leaf trash.
|Symptoms and damage|
Giant African snails usually feed on decomposing vegetation. However, when introduced to a new environment they will feed on a wide range of plants, including cocoa, rubber, banana, papaw, citrus, sweet potato, cassava, most vegetables, legumes and ornamentals. They will also consume fallen fruit, garbage, human and animal excreta - and even the bodies and shells of other giant African snails.
|How is the pest controlled?|
Giant African snail is difficult to eradicate. The successful Gordonvale eradication campaign involved an intensive eight month program of community education, snail collection and baiting.
The main risk of giant African snail introduction to Australia is via plant material, crates, shipping containers, machinery and motor vehicles. They could also be introduced at the egg stage in soil. To reduce the chance of an incursion, the Australian Quarantine and Inspection Service (AQIS) conducts targeted inspections of containers from countries that are considered high risk for giant African snails. In some cases, steam treatment of vehicles and, if necessary, fumigation of high-risk equipment is conducted in order to reduce the risk of it entering Australia.