Giant African snail (Achatina fulica Bowdich, 1822) - As a Molluscan Pest: First Report on Mulberry from Aurangabad, (M.S), India

Sunil B. Avhad and Chandrashekar J. Hiware

Dr. Babasaheb Ambedkar Marathwada University, Aurangabad (M.S), India.

E-mail- sunil_zoology@rediffmail.com, drhiware@rediffmail.com

Sunil B. Avhad

Abstract:  The Molluscan as a pest of agriculture and horticulture have already been known in many regions. The present communication deals with molluscan pest the Giant African snail; Achatina fulica (Bowdich, 1822) observed a first report on mulberry fields from Aurangabad district, Maharashtra during June.2009- May. 2011. The incidence of snails was recorded in all the tehsils, in the every months starting from August to December. According to sericulturists of the area, severe cocoon loss was not only due to infestation but also due to the stinking smell of mucus layer (both wet and dry conditions) released by the Giant African snail, Achatina fulica on mulberry plant. The silkworm showed an aversion towards feeding on such leaves and as result, considerable quantities of harvested leaves were wasted without converting in to silk cocoons. 

Key-words: Giant African snail, Molluscan pest, Mulberry, Aurangabad. Maharashtra state.

Introduction:

In India, sericulture is one of the most important agro and forest based cottage industry, earning a foreign exchange of Rs. 400 corers / annum and providing gainful employment to over six million peoples. Technically sericulture is rearing of silkworms either on mulberry or non-mulberry plants for production of silk. Today India is the second largest silk producer of raw silk and also has the distinction of being the world’s largest consumer of silk. In developing countries such as India, agriculture and agro-based industries play a vital role in the improvement of rural economy. The limited availability of land, the limited cash returns and agriculture being confirmed to one or two seasons in the year, have made villages to look for supporting rural industries and one of them is sericulture. Maharashtra, a state without a tradition of silk production has a large gap between demand and supply of raw silk and more than 4,000 (Anon., 2008). This demand for raw silk could become a source of rural employment within Maharashtra. The main constraints to sericulture in Maharashtra state were: lack of mulberry tree varieties adapted to local agro-climatic conditions, lack of suitable silkworm races, and lack of knowledge and skills among the farmers.

Mulberry (Morus spp.) leaf is the only natural food for the silkworm, Bombyx mori L.  It is a perennial, evergreen, luxuriant crop cultivated in all types of soils, both under rainfed and irrigated conditions. The crop is prone to depredation of diverse organisms, because of its fast growth and green foliage throughout the year, in varying proportions either for space, food or both. So far, over 300 insect and non-insect species of pests are known to infest mulberry in varying intensities during different stages of the crop and seasons (Naik, 1997). Though the frequent leaf picking and pruning of the attack of pests, many of them still final enough time and place on mulberry for feeding and breeding on it. From India, about 100 insect pests have been reported on various varieties of mulberry.

Among the non- insect pests of agricultural as well as horticultural crops, the Giant African snail, Achatina fulica Bowdich is reported as most important one in many parts of the world. The characteristic symptom of the infestation was that the snails were feeding on the bark of the stem. This brings down the nutritive value as the vascular is injured and senescence of mulberry leaves leading to defoliation. The incidence is one of the major factors that decide the productivity and profitability in sericulture is the maximization of quality mulberry leaf yield per unit area. However, the mulberry leaves from snail attacked plants are not suitable for silkworm feeding as they are found to be nutritionally inferior (Shree et al., 2006). 

Materials and methods:

The molluscan pests’ collection was carried out in six sites namely Aurangabad, Sillod, Fulmbari, Khultabad, Paithan and Gangapur from June 2009 to May 2011. All the sites were visited and sampled monthly with different collection methods. All the specimens were identified with the help of available literature and Zoological Survey of India, Western office, Pune division, India.

Results and discussion:

Achatina fulica (Common name: Giant African snail, Phylum: Mollusca, Class: Gastropoda, Superfamily:  Achatinoidea, Family: Achatinidae, Subfamily: Achatininae, Genus: Achatina, Species: fulica). Occurrence from the mulberry plant, Morus alba L., from Gangapur mulberry fields, Aurangabad district, Maharashtra, India throughout year but active during rainy season. Type of Damage and Symptoms is as extensive chewing of blossoms, leaves, and shoots stunts the growth of young trees and trees that have been top worked. The land snail can especially be a problem following wet winters and springs. Land snail feeding is not a problem in mature groves. Thick, dry leaf mulch suppresses snail numbers and large trees tolerate any modest chewing.

Giant African snail (Achatina fulica Bowdich)

The adult snails have a height of around 7 centimeters (2.8 in), and their length can reach 20 centimeters (7.9 in) or more. The shell has a conical shape, being about twice as high as it is broad. Either clockwise (sinistral) or counter-clockwise (dextral) directions can be observed in the coiling of the shell, although the right-handed (dextral) cone is the more common. Shell colouration is highly variable, and dependent on diet. Typically, brown is the predominant colour and the shell is banded (Skelley et al., 2011).

In the present study the occurrence of the Giant African snail, Achatina fulica is reported from Gangapur, Aurangabad (M.S), India mulberry field during rainy season but there occurrence is throughout the year, due to hibernation time these are not much active as compare to rainy season. Shree et al., (2006) also report on the occurrence of the Giant African snail, Achatina fulica in some parts of Karnataka is infest mulberry. The incidence of snails was recorded in all the villages, in the every months starting from August to December. According to sericulturists of the area, severe cocoon loss was not only due to infestation but also due to the stinking smell of mucus layer (both wet and dry conditions) released by the Giant African snail, Achatina fulica on mulberry plant. The silkworm showed an aversion towards feeding on such leaves and as result, considerable quantities of harvested leaves were wasted without converting in to silk cocoons.

Acknowledgement

 The authors are thankful to the all the farmers from Aurangabad district and to the University authorities, Head, Department of Zoology, Dr. Babasaheb Ambedkar Marathwada University Aurangabad, (M.S.) India, for providing necessary laboratory and library facilities during this  work.

References

Anonymous, (2008).  Annual Progress Report, 2008, CRS, BAIF, Uruli Kanchan.

Naik, S. L. (1997). Bioecology of thrips infesting mulberry. M.Sc. Thesis, University of Agricultural Sciences, Bangalore 77p.

Shree, M. P; Ravi Kumar K and Nagaveni, V (2006). Infestation of Giant African Snail on Mulberry. Indian Silk, Vol.45, No.6, Pp. 14-16.

Skelley, P. E; Dixon, W. N; and Hodges, G. (2011). Giant African land snail and giant South American snails: field recognition. Florida Department of Agriculture and Consumer Services. Gainesville, Florida.