NEW RECORDS OF PESTIFEROUS LAND MOLLUSCS FROM RAJASTHAN, INDIA

More than 1500 species of land mollusc are recorded from India. Out of these, twelve species viz. Achatina fulica Bowdich, Ariophanla bajadera (Pfeiffer), Ariophanta ligulata Ferrussac, Ariophanta solata (Benson), Bensonia monticola Hutton, Cryptozona belangiri Deshayes, Cryptozona (Nilgiria) semiru~ata (Seck.), Cryptozona (Xestina) bistrialis Beck., Macrochlamys indica (Godwin-Austen), Opeas gracile (Hutton), Zootecus insularis (Ehrenberg) and Mariaella dussumieri (Gray) are known to cause damage to agricultural, horticultural and plantation crops in India (Raut & Ghosh, 1984; Srivastava, 1992 and Subba Rao, 1975). So far, only two pestiferous land moliusc Opeas gracile (Hutton) and Zootecus insularis (Ehrenberg) are reported from Rajasthan (Subba Rao & Mitra, 1979 and Raut & Ghosh, 1984). Laevicaulis alte (Ferussac) is reported from Udaipur, Rajasthan but not as a pest (Ray & Mukherjee, 1963). The present paper reports for the first time, two more pestiferous land mollusc Laevicaulis alte (Ferussac) and Macrochlamys indica (Godwin-Austen), as severe pests of neem seedlings in forest nurseries of Rajasthan along with new distributional records.

Diagnostic Features Specimens young to adult, length 7 mm.to 62 mm.A soft bodied animal without shell.Body elongate, oval on contraction, linear when extended.Head with two pairs of tentacles, retractile.Dorsal surface blackish brown, mantle is pigmented with dark brown colour usually with a yellowish line down the middle.Ventral surface creamish white in colour, Hermaphrodite.
Remarks: First time reported as pest of neem seedlings.All stages feed voraciously on neem seedlings in forest nurseries resulting in mortality.Diagnostic Features: Shell perforate, pale brown with smooth and polished surface, with five and half whorls and low spire.Last whorl much wider than the rest, rounded at the periphery.Aperture is oblique, columellar margin curved and oblique, peristome thin.
Host Plants : It has been reported as a pest of LujJa sp.Beans, Lettuce, Cole crops, Moringa oleifera, Amaranthus b/itum.Abelmoschus esculentus, Tagetes spp.and Chrysanthemum sp.(Raut & Ghosh, 1984) and Money plant (Subba Rao, 1975).Habit and Habitat: Land molluscs are restricted to moist habitats.They hide during the day in holes,-grass dumps etc, and become active at night.The snails and slugs aestivate or hibernate during adverse conditions.The aestivating/hibernating mollusc population is of great significance as this population becomes responsible for "restocking an infested area" With the onset of monsoon the snails and slugs which have survived the stress and strain of adverse climatic conditions during aestivation/hibernation becomes active again and resume their biological activities.Molluscs prefer slightly alkaline sandy soils (pH 7.0-8.0).The fallen leaves, debris, animal dung and dead snails serves as food for mollusc.The eggs are laid in moist places.The cluster contain 15-100 eggs, depending on the age of the mollusc.Mollusc rehabilitates itself by rebuilding its population, spread all over again and becomes a menance.
Nature of Damage : Both Macrochlamys indica and Laevicaulis aile are voracious plant feeders and devour all parts of the seedlings.The young molluscs prefer tender leaves and stem and avoid harder portions, while older ones attack young as well as grown up seedlings.They feed voraciously on the main tender stem above the collar region by licking the bark which results in the girdling of the stem and subsequently the seedlings die due to the damage to the cambium.The debarked stem becomes very fragile and weak and •easily breaks off with the slightest lnovement of wind.It has been observed that damage is beyond survival, in seedlings ranging from 10 cm -15 cm, as the seedlings are eaten up completely, older seedlings are defoliated and stem is debarked and the plant is able to revive when prevented from further attack.

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It is being reported for the first time from Rajasthan and as a pest on neem seedlings.It is a voracious plant feeder and found devouring young neem seedlings in different forest nurseries of State Forest Department (SFD) Rajasthan and Arid Forest Research Institute, Jodhpur.