The giant African snail scientifically called Achatina fulica is one of the large land snails that were believed to be originated from Africa. These snails can grow up to 8 inches in length and 4 inches in diameter. A. fulica can eat anything from garden plants to agricultural crops. These snails are hermaphrodites meaning they have both male and female reproductive organs and to allow cross fertilization reproductive glands mature at different times. A. fulica reproduces rapidly, they lay around 400 eggs in single clutch and around 1000 eggs per year. The eating habitat along with high reproducible capacity has made this snail as one the major man made pest around the globe recently. The life cycle of snail starts with egg stage lasting for 3 to 15 days. The young snail grows and mature around six months after hatching. Each snail lives up to six years and produces around 5000 eggs in life span.
Giant African snails are active in night and hence they can be observed feeding during night. During the rainy seasons, snail's activities are highest and they either aestivate or less active in dry weathers. During the unfavorable conditions, snails burrow into the ground and the opening of the shells are sealed with calcified substance. They can withstand the unfavorable conditions up to several years in the aestivation conditions, making difficult in control measures. In the initial years of introduction, the effects are very less as the damage seen to agricultural crops is very minimal. As the population explosion occurs, they eat and damages varieties of agricultural crops ranging from vegetable, fruits and ornamental crops. Apart from the loss caused to the agricultural crops, A. fulica harbors parasitic nematodes Angiostrongylus cantonensis, which causes meningoencephalitis, which is also a concern for human health by this snail.
Giant African snails are now reported from major regions of the globe due to the activities of Man. In some places these snails entered accidentally and in some places they were brought initially as pets and but later introduced into the local ecosystem. They are now termed as pest due to the imbalance caused to the ecosystem by them. In Nature these snails have very less predators and with high reproductive rate, they overpopulate any ecosystem in no time. Hence in some countries there is even strict ban on raring them as pets.
Controlling Giant African snails are challenge to mankind. There are only few naturally occurring predators present in Nature for these snails and in the exotic places where snails are considered as introduced pests, no natural enemies are present. Control of snails includes varieties of methods like Physical, chemical and biological control. None of the methods are successful except for the manual collection and destroy method. The molluscicides are less effective for these snails and application of molluscicides have other side effects in the agricultural fields. Similarly the biological control also has its own limitations, there are cases where the predators released in fields, instead of controlling A. fulica, have eliminated other species of molluscs.
The manual collections of adults and eggs of giant African snails from fields and gardens and destroying them by either breaking the shells or drowning in salt or hot water are much simpler but laborious procedure. This requires community participation in the infested area, wherein the people from the infested area work together and destroy the snails and eggs in the fields. Care should be taken in this method in avoiding getting physical contact with the snails during the procedure of collection, as these may contain parasites responsible for meningoencephalitis.
Once established it is very difficult to eradicate giant African snail as the reproductive capacity of these snails are high; they have less predators and mechanism of aestivation. Prevention is better in controlling these snails and hence Countries should adopt procedure of checking of all import agricultural products, vehicles, and containers including ships coming from the affected regions. The giant African snail is the one of the classical example of manmade disastrous in making the species as major pest in agricultural land. The combined controlled measure of physical, chemical and biological method applied simultaneously or sequentially will help to eradicate the giant African snail menace.
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