Effect Of aestivation Duration and the Post Aestivation Egg laying performance of Archachatina marginata

Effect Of aestivation Duration and  the Post Aestivation Egg laying performance of Archachatina marginata

O.G Sodipe^* and O. A. osinowo.

Department of Animal Physiology, University of Agriculture, P.M.B. 2240, Abeokuta, Nigeria.

                                                e-mail: bunmigraphics@yahoo.com

                 Abstract

The study focused on the evaluation of the effect of aestivation duration and the post aestivation egg laying performance of Archachatina marginata using a total number of 40 Archachatina marginata snails weighing between 150 -250 g.  The experiment was conducted at the Snail Research Unit of the College of Animal Science and Livestock Production, University of Agriculture, Abeokuta.  Archachatina marginata were exposed to different period of aestivation with 10 snails per replicate over a period of 6 weeks between February and March. Result shows that the egg laying performance decrease were significantly (P<0.001) with weeks of aestivation. A sharp increase in egg laying performance was observed two weeks after the aestivation treatment imposed was withdrawn. The number of clutches of egg laid decrease were significantly (P<0.001) with weeks of aestivation.

                         Introduction

Aestivation is a natural phenomenon is known to interrupt the normal physiological process of the snails leading to the slow growth rate (Odiette, 1999). Metabolic depression is a reduction in metabolic rate to below the normal resting value (Guppy and Withers, 1999). The impact of stressful environmental condition on snails, are been reduced by the behavioural and physiological responses to dormancy which enhances the preservation of their body fluids. Snails survive many months without food and water under aestivation (Akinnusi, 1998). Snail population have declined considerably, basically because of the impact of human interference with the snails’ natural habitat.

Aestivation may be regarded as an important phase of the snail’s life cycle because it is a survival mechanism. The crucial elements for survival during aestivation are water retention and sufficient energy reserves (Storey, 2001). The aestivation in snail is synonymous to ‘fasting’ in other animal and this fasting exhibit benefits like clearance of the gut, healing, rejuvenation and fertility. Hence, it posses the question that does aestivation have such physiological benefits? Could the long term effects of aestivation enhance the post aestivation egg laying performance of Archachatina marginata.

              Materials and Method

Experimental Animals and Management

The experiment was conducted at the Snail Research Unit of the College of Animal Science and Livestock Production, University of Agriculture, Abeokuta. A total of 40 Archachatina marginata snails weighing between 150 and 250g were used. The snails were obtained from the neighbouring market and were acclimatized for 2 weeks to normalize the previous treatment they have been exposed to. The Archachatina marginata were grouped into 4 groups and were exposed to different period of 6 weeks.

Factors investigated are:

Duration of Aestivation: 0 vs 2 vs 4 vs 6 weeks

Replicate: 10 snails (later paired into 5 after aestivation)

Treatment:       A – Control (No aestivation)

                        B – 2 weeks of aestivation

                        C – 4 weeks of aestivation

                        D – 6 weeks of aestivation

Snails in treatment A were placed in basket that have damp top humus soil oven dried  1.65 kg and sprinkled with 400 ml of water initially. The soil was subsequently sprinkled with 50 ml of water once week. The snails were fed a mixture of layers mash and dried grounded pawpaw leaves (ratio 1:1) daily. The feed and water were provided in plastic troughs. Snails in treatment B, C and D were placed in basket oven dried soil without feed and water. The egg laying pattern relative to the experimental treatments was monitored. Data collected were analysed using SPSS, 1999.

                       Result and Discussion

Deprivation of food and water deprivation in snails resulted in aestivation by (Odiete, 1999; Storey, 2001; Omoyakhi, 2007) was confirmed in this study as the snails withdraw into their shells and covering the aperture with epiphragms, although the epiphragm was continuously  replaced at intervals. The aestivation and post aestivation egg laying performance of Archachatina marginata are presented in Figure 1. The egg laying performance decrease were significantly (P<0.001) with weeks of aestivation. A sharp increase in egg laying performance was observed two weeks after the aestivation treatment imposed was withdrawn. The aestivation and post aestivation number of clutches of egg laid by Archachatina marginata are presented in Figure 2.  The number of clutches of egg laid decrease were significantly (P<0.001) with weeks of aestivation. The number of clutches did not increase with the duration of post – aestivation. 

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Akinnusi, O.1998.  Introduction to snail and snail farming. Omega Science

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SPSS 1999. Statistical Package for Social Sciences. SPSS for Microsoft Windows

            Release 6.0 User’s Manual