Giant African Snail (Achatina fulica)

Giant African Snail (Achatina fulica) (Bowdich, 1822) is a terrestrial gastropod species native to the continent of Africa and belonging to the family Achatinidae. It is considered the most important land snail pest in tropical and subtropical regions. The family is represented in Africa by approximately 200 species and 13 genera.^【1】   The shell shape is high and pointed, consistent with the bimodality observed in stylommatophoran snails.^【2】 

The native range of the species extends along the eastern African coast from Mozambique and Natal to Kenya and Somalia. With increased human mobility and the globalization of transport and trade, Achatina fulica has been accidentally or intentionally introduced to many regions outside Africa. The species reached Madagascar in the 1800s and from there spread to the islands of the Indian Ocean, India, Southeast Asia and the Pacific islands.^【3】 

Its spread in South America is linked particularly to commercial attempts at “escargot” farming. The first introduction to Brazil occurred in 1988 in the state of Paraná, where specimens brought from Indonesia were sold at agricultural fairs. After the commercial venture failed and a market failed to develop, producers abandoned the snails into the wild, landfills and riverbanks. This led to the rapid spread of the species in urban areas ornamental gardens and agricultural fields, where it became an invasive species.^【4】 

^{Giant African Snail (Achatina fulica) -} Pixabay

Achatina fulica’s digestive system consists of the buccal mass, esophagus, crop, stomach, intestine and rectum; associated structures include salivary glands and the digestive gland. The mouth is located ventrally at the anterior tip of the snout and is semicircular in shape.^【5】 

Feeding Mechanism: During feeding, the protractor muscles of the buccal mass contract, pushing the radula toward the mouth. The radula has transverse rows of teeth arranged in a 64.1.64 formula, with approximately 140 rows in an adult individual. The central tooth has a narrow and elongated body; ectocones and endocones are present in lateral teeth up to the 14th row, while marginal teeth have ectocones larger than those of the lateral teeth.

Digestive Organs: The esophagus is narrow with thick walls and connects posteriorly to the crop. The crop is a large, thin-walled, two-chambered sac approximately 50 mm long, functioning in storage and preliminary digestion. The stomach is heart-shaped and embedded within the digestive gland. The salivary glands are paired, lobed and cream-white in color; their secretions may contain amylase enzyme.^【6】 

Activity and Dormancy: Achatina fulica is a nocturnal organism. Its activity depends on humidity levels; it becomes active when relative humidity exceeds 50%. During dry periods or unfavorable conditions, it enters estivation (summer dormancy) or hibernation (winter dormancy). During estivation, it seals the aperture of its shell with a protective layer called an epifragm. During this process, heart rate may drop from 52 to 8 beats per minute.^【7】 

Reproduction: The species is hermaphroditic. During shell growth, male gametes are produced first; after growth ceases, both male and female gametes are produced, achieving full sexual maturity. Mutual copulation is common, but self-fertilization is rare and results in mostly sterile eggs. Achatina fulica is oviparous. After mating, sperm can be stored for extended periods, enabling egg production up to 341–382 days after a single mating event. An individual may lay an average of 900–1200 eggs per year. Hatchlings remain underground for the first 5–15 days, consuming their own eggshells.^【8】 

^{Giant African Snail (Achatina fulica) -} Pixabay

As an Agricultural Pest: It is a polyphagous herbivore that damages numerous crop plants ornamental plants and tree seedlings. Seedlings are the most vulnerable stage. Economically significant plants affected include banana papaya coffee cocoa rubber bean peanut and various vegetables. It also feeds on decaying plant material and carrion (necrophagous behavior).^【9】 

As a Disease Vector: Achatina fulica poses serious risks to human health. It serves as an intermediate host for the nematode Angiostrongylus cantonensis, which causes eosinophilic meningoencephalitis in humans. It is also a potential host for Angiostrongylus costaricensis, which causes abdominal angiostrongylosis in the Americas. In terms of plant pathology, it has been shown to spread spores of Phytophthora palmivora, the pathogen responsible for black pod disease in cocoa plants, via its feces.^【10】 

Physical Control: Manual collection and destruction of snails and eggs is a common method. Collected snails are crushed buried in deep pits or covered with lime. Additionally, digging trenches or installing barriers around agricultural fields is recommended.

Chemical Control: Poisoned baits containing metaldehyde and calcium arsenate have historically been the most commonly used chemical method. However, their effectiveness decreases during rainy weather.^【11】 

Biological Control: Predatory snails such as Euglandina rosea and Gonaxis species, as well as flatworms such as Platydemus manokwari, have been introduced in various regions to control Achatina fulica. However, there is no conclusive evidence that these generalist predators effectively suppress A. fulica populations. Instead, they have been documented to cause severe ecological damage by driving native snail species to extinction. For this reason, countries such as Brazil do not recommend the use of such biological control methods.^【12】