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Factors Inducing Aestivation of the Giant African Land Snail Achatinafulica Bowdich (Gastropoda : Achatinidae)Md. Sayeedur Rahman z z z z z Srimanta Kumar Raut1Published online : Received 22 February 2010 / Accepted 24 March 2010© The Author(s) 2010. This article is published with open-access at springerlink.comAbstract The giant African land snails Achatina fulicaBowdich occurring in Kolkata, West Bengal, India undergoaestivation with the advent of adverse conditions by theend of October or early part of November, each year.Experiments were conducted to study the factors inducingaestivation in these snails. It is revealed that the type ofplant-foods, the length of starvation, the degrees oftemperature and the percentages of relative humidity arethe factors inducing aestivation in A. fulica of course, justat the onset of aestivation. It is also observed that,depending upon the severity of these factors the snailsrequired different number of days to aestivate. Even, undersimilar situation individuals belonged to lower size groupsstarted aestivation earlier than those of the snails belongedto higher size groups. The cumulative effects of certainabove mentioned factors sometimes, either delayed oraccelerated the process of aestivation.Keywords : Land snail, Achatina fulica, Factors, Aestivation.IntroductionTerrestrial molluscs in cold and temperate countrieshibernate and aestivate respectively with the onset ofadverse climatic conditions (Mead, 1961; Godan, 1983;Md. Sayeedur Rahman and Srimanta Kumar Raut1Ecology and Ethology Laboratory,Department of Zoology, University of Calcutta35 Ballygunge Circular Road, Calcutta 700 019, Indiae-mail: srimantakraut@gmail.comProc. zool. Soc. (2010) 63 (1) : 45–52ISSN No. 0373-5893© 2010 ZSTH E ZO OLOGICAL SOCIE TYKOLKATARaut and Ghose, 1984; Raut, 1991; Gomot and Gomot,1991; Fields, 1992; Raut and Barker, 2002; Ahmed andRaut, 2008). Hibernation is primarily a response to lowtemperature while aestivation is a response to reducedrelative humidity. In both cases the snails and slugsattempt to overcome the unfavourable conditions byadjusting their physiological conditions (Howes andWells, 1934a,b; Pelseneer, 1935; Hyman, 1967;Barnhart, 1986a,b; Gomot and Gomot, 1991; Fields,1992, Panigrahi and Raut, 1994). The length ofhibernation and aestivation has also been recordedfor a number of species by different workers (Vignal,1919, 1923; Longstaff, 1921; Flower, 1922;Leeuwen, 1932; Baker, 1934; Walton, 1963; Hyman,1967; Godan, 1983; Raut and Ghose, 1984; Raut,1991). Shelford (1913), Kondo (1964), Chock andNakao (1951), Mead (1961) and Raut and Ghose (1984)have paid attention to record the factors influencingdormancy in land molluscs. But, from these studies itis very difficult to get an idea on the factor(s) inducingaestivation/hibernation in terrestrial molluscs. Since, stillto-date no methodical work has ever been carried outby any worker to determine the factors inducingdormancy in land gastropods, in the present programme,an attempt has been made to study the same. As thegiant African land snails Achatina fulica Bowdich havea world-wide distribution, and they are adapted bothfor hibernation and aestivation the experimental studieswere designed through the use of these snails. The snailsRESEARCH ARTICLE