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Moulting Effect on Fat and Water Contents in Silkworm Bombyx Mori L., Race Nistid White.

M.A. Qader
Senior Research Officer
BSRTI, Rajshahi.

T. Haque
Senior Reseach Officer
BSRTI, Rajshahi.

S.U. Ahmed
BSRTI, Rajshahi.

Abstract/ Executive Summary:

A number of works have been conducted on the change of the amount of water and various chemical compounds during developmental stages in the silkworm, Bombyx mori L. (Nimierko eta/., 1956; Hiratsuka, 1975; Chinya and Ray, 1973; Rahman and Sana. 1984; Gupta and Pathak, 1984). However, these works are not sufficient. The mean measurement of fat and water contents during newly hatched, premoulting, moulting and post-moulting periods of different instars were calculated. The percentage of fat conien1 gradually decreased from newly hatched larvae to fifth instar larvae arid that the differences among the instars for the four sieges were highly significant (P<0.0 !) except for 1st and 2nd and 4th and 5th instars. Within each instar, the fat content was significantly low during musing period.

Keywords: Moulting effect, Fat and Water contents in silkworm, Newly hatched larvae, Premo¬ulting larvae, Moulting larvae and newly moulted larvae.

Location: Bangladesh Sericulture Research and Training Institute

Start Date:

End Date:

Program Area: Variety and Species

Commodity: Silkworm

Objectives:

To study the effect of moulting on fat and water contents in silkworm, Bombyx mori L., race-NISHD WHITE.

Methodology:

The eggs of B. mori, race-NISTID WHITE were collected from the breeding section of the Bangladesh Sericulture Research and Training Institute, Rajshahi. The experimental materials consisted of: (a) newly hatched larvae, (b) premoulting larvae, (c) moulting larvae and (d) newly moulted larvae of different instars. The larvae were starved for 24 hours to clear out the gut. After 24 hours, the worms were weighed, made unconcious by Chloroform vapour and then dried in an oven at 110⁰C until constant weight was obtained, the diffe¬rence between the dry weight and fresh weight gave water content from which water percentage was calculated. Fat content was estimated following the methods of Folchs et al. (1975) and Abasa (1972). The mean measurement of fat and water contents during newly hatched, premoulting, moulting and post-moulting periods of different instars are pre¬sented. The percentage of fat content gradually decreased from newly hatched larvae to fifth instar larvae arid that the differences among the instars for the four sieges were highly significant (P<0.0 1) except for 1st and 2nd and 4th and 5th instars. Within each instar, the fat content was significantly low during mousing period. Hiratsuka ("975), however, reported higher fat content in the premoulting lervae the newly moulted ones. On the contrary, the percentage of water content showed a reverse trend. It gradually increased from newly hatched larvae to fifth instar larvae. Again, within each instar the percentage of water content was higher during moulting stage.

Source of Information: University Journal of Zoology, Rajshahi University. 7: 49-51, 1988.

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

An estimation of correlation coefficient between fat and water contents revealed a significantly negative value (r= -0.78, P<0.01 ). Similar significant negative association between these two components has also been reported by Gupta and Pathak (1984), The decrease in the percentage of fat content in the moulting larvae has been described by Hiratsuka (1975) who opined that the decrease was due to the utilization of fat as energy source for the formation of new skin and casting off the old one. The increase in the percentage of water content during moulting, on the other hand, may be due to rapid catabolization of fat particles yielding water (Gupta and Pathak, 1981). Duchateau-Bosson et al. (1961) reported a decrease in the concentration of various amino acids after moults and reasoned that this may be due to their incorporation in the formation of larval tissues.

Knowledge Management: Journal