Achatina fulica (Ferussac, 1821)

Achatina fulica is one of the 100 top invasive species in the world. Originally a native of East Africa, it has now invaded most of the Indo-Pacific region. A serious pest in agro-horticultural systems, it is used as food for humans, poultry and fishes.

Four sub-species identified - Achatina fulica hamillei Petit, 1859; Achatina fulica rodatzi Dunker, 1852; Achatina fulica sinistrosa Grateloup, 1840 and Achatina fulica umbilicata Nevill, 1879.

Achatina fulica is a hermaphrodite - each individual has both testes and ovaries and is capable of producing both sperms and ova. Self-fertilisation rare, occuring only in small populations. Snails of similar size show bilateral mating, while those of unequal size show unilateral mating with the larger one acting as the female. Mating behaviour includes bringing heads and front parts against each other. Courtship can last upto 30 minutes, while actual transfer of gametes can last for two hours. Transferred sperm can be stored within the body for up to two years. Thus these snails can lay eggs over a period of several months after only one mating. A snail may lay 5-6 clutches per year, with 200 eggs per clutch. Eggs are laid in damp places and show a hatching viability of about 90%. Eggs are yellow or cream in colour and 4.5 - 5.5 mm in diameter. Thus, it breeds rapidly, out-competes native species of snails and reaches large numbers in short periods due to their prolific breeding habits.

Captivity: 5-6 years. Wild: upto ten years.

Height: around 7 centimetres. Length: can reach 20 centimetres or more.

Adult size is reached in about six months, after which growth slows but does not ever cease.

Conical shell, twice as high as it is broad. Dextral coiling more commonly seen than sinistral coiling. Shell colouration highly variable and dependent on diet. Typically, brown bands running across the spirals.

Buried underground throughout the day, these snails emerge from their damp hideouts at dusk and feed throughout the night. Most active during the rainy season.

Achatina fulica is a macrophytophagous snail and feeds on wide variety of plants, fruit and vegetables. Because of its prolific feeding habitats, it can cause significant damage to agricultural and horticultural crops. According to Raut and Barker (2002) Achatina fulica feeds on more than 500 plants of agricultural and horticultural importance, including cuttings and seedlings of plants.

Parasites of Achatina fulica include: 1. Aelurostrongylus abstrusus. 2. Angiostrongylus cantonensis - causes eosinophilic meningoencephalitis. 3. Angiostrongylus costaricensis - causes abdominal angiostrongyliasis. 4. Schistosoma mansoni- causes schistosomiasis, detected in faeces. 5. Trichuris spp. - detected in faeces. 6. Hymenolepis spp. - detected in faeces. 7. Strongyloides spp. - detected in faeces and in mucous secretion.

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The Giant African Land Snail Achatina fulica is considered as one of the world’s most damaging 100 invasive alien species. Two individuals of the Giant African Snail were brought to India from Mauritius by the pioneer of malacology in India, William Benson, in 1847. Benson left India soon after his return from Mauritius and handed the snails to a friend and neighbour in Chowringee, Kolkata, and it was the neighbour who subsequently released them in his garden. From these two individual snails the species spread throughout much of South Asia.

Found in agricultural areas, coastland, natural forest, planted forests, riparian zones, scrub/shrublands, urban areas, wetlands, gardens and homesteads.

Non-endemic

Very common species during rainy season in India. The population density can vary from 2 to 70 individuals per 10 metre square.

Achatina fulica is a serious pest to agri-horticulural systems throughout the Indo-Pacific Islands (Raut 1982). Plant diseases such as black pod disease caused by Phytophthora palmivora are also spread through the faeces of Achatina fulica (Raut and Barker 2002; CAB 2003). In India, A. fulica causes more damage to vegetables belonging to the families Cruciferae, Cucurbitaceae and Leguminoseae. Achatina fulica can also act as a vector of human diseases such as angiostrongylosis and eosinophilic meningoencephalitis, by acting as the hosts of Angiostrongylus cantonensis (CAB 2003; Santos Carvalho et al. 2003). This parasite enters humans through eating raw or under-cooked snails.

Not Evaluated.

Not protected. An invasive pest species.

Achatina fulica is used as food for humans, poultry and fishes; and for medicinal and research purposes.