Achatina fulica

The Snail giant African , ( Achatina fulica , sometimes Lissachatina fulica ), is a large snail whose adults are in general approximately 8 cm long but can exceed 20 cm.

Its shell is of conical form and is twice higher than broad. Its color is brown with darker transverse marks. This snail is herbivorous polyphagous, i.e. it is not very demanding as regards consumed plants. It can reproduce 6 to 7 times per annum at a rate of 200 eggs laid each time (with a rate of survival of 90%). It becomes adult in six months and saw a year and half in general, however certain individuals were maintained living six years in breeding.

Originating in Africa, the species was largely introduced in Asia, in the islands of the Pacifique and the Indian Ocean where its size and its important rate of reproduction quickly posed problem in the absence of predatory natural: in addition to the damage which an uncontrolled population can subject the cultures, Achatina fulica presents also public health problems, being the vector of parasites and disease-causing agents of which some can touch the human beings.

Among measurements taken in order to control the African giant snail populations, the biological Fight by the introduction of predatory species of snails (like the Euglandina rosea ) and of flat worms was shown relatively ineffective and sometimes had dramatic consequences on populations of other snails autochtones.

Extension of the habitat

Its habitat of origin is of Africa, especially the Kenya and the Tanzania. Today one finds it in almost all the tropical and wet areas of the sphere where it was introduced sometimes in a voluntary way, often involuntarily. It is able to survive in habitats varied like the agricultural zones, the coasts, the waste grounds, the forests natural, the urban areas or wet. It is active the night and takes refuge in the ground during the day.

Measurements of forty taken in its connection made it possible to intercept many imports of this species for example on the ground of the the United States. However, a fashion recently appeared to preserve this species as pet but this is illegal in several countries of which the United States.

Risks of public health

The African giant snail is the Vecteur of Angiostrongylus cantonensis (Nématode; Protostrongylidae), the round worm responsible for the eosinophilic Meningoencephalitis at the human ones whose expansion corresponds to that of snail. It is not the only vector, other species of snails introduced into the tropical areas also transmit this parasite.

Fight against Achatina fulica

Once the giant snail introduces some share, it is very difficult, often impossible with éradiquer. The best methods of fight seem to be those which consist to eliminate it with the hand, the use of Molluscicide S, flame thrower and biological Lutte. In certain areas, one tries to promote his consumption by hoping that this one could decrease its populations. But it is always dangerous to promote a harmful species because them risks to encourage people to spread it still more.

The attempts at biological Fight, as for them, do not seem to have been of a great efficatity against Achatina fulica and are the cause of the reduction and sometimes of the disappearance of local species.

One of the methods of biological Lutte the most used against African giant snail is the predatory snail introduction, especially of Euglandina rosea .

The first tests of such a control took place in the archipelago hawaien. Fifteen carnivorous snail species were introduced deliberately. Last nines of them were not established, one does not know to become it of three different, the three last posed all of the environmental problems: Euglandina rosea , Gonaxis kibweziensis , Gonaxis quadrilateralis . Moreover, they did not have any manifest impact on the populations of Achatine.

Such harmful attempts took place elsewhere. Euglandina rosea was in particular introduced in French Polynésie, in the American Samoa, on Guam and in other islands of the Pacifique and the Indian Ocean.

In addition to the introduction deliberated on predatory snails, the flat Ver Platydemus manokwari was also introduced although less widely. This disease-causing agent actually seems to have contributed to decrease the giant snail populations although its real impact is not completely shown. However, this worm was also responsible for the endemic decline of species S on the island of Guam.

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