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Studies on Some Biochemical Parameters of
Haemolymph of Bivoltine Silkworm, Bombyx mori L.
in Different Rearing Seasons
Awquib Sabhat
Dr. A.M. Sofi
Ph.D
2011
Key words : Silkworm, Haemolymph, Mulberry
varieties, Environment, Economic characters
ABSTRACT
The present investigation was undertaken to analyze the larval performance, economic
characters and biochemical aspects of eleven races of Bombyx mori L. namely SH6, SKAU-R-6,
SKUAST-31, Dun6, Yakwei and CSR5 (oval races) and NB4D2, SKAU-R-1, SKUAST-13,
SKUAST-28 and CSR4 (constricted races) were selected on the basis of their performance to
seasons and cocoon productivity. NB4D2 and SH6 a constricted and an oval race were taken as
the control. The changes in the biochemical composition of haemolymph reflect tissue specific
changes at different developmental stages in response to seasons. The changes in the levels of
protein and free amino acids in the haemolymph of all the races were observed during 4th moult,
5th instar and pupal period. The levels of total protein in the haemolymph, increased from first
day of 5th instar till sixth day. The protein levels decreased on seventh day in all the races. A
sustained decrease in the haemolymph proteins was observed during the pupal development in
all the races. The levels of free amino acids, which were high during 4th moult, declined through
the 5th age of larval development till spinning. Among the oval races, the haemolymph protein
levels were found to be significantly higher in SKAU-R-6 followed by SKUAST-31, SH6, Dun6,
CSR5 and Yakwei, whereas, the larvae of SKAU-R-1 showed a relatively higher levels of
protein followed by NB4D2, SKUAST-28, CSR4 and SKUAST-13. The free amino acid levels
decreased gradually from prepupal stage but increased again towards the end of pupal period.
The larvae during 4th moult recorded highest levels of free amino acid in SKAU-R-6 followed by
SH6, SKUAST-31, Dun6, CSR5 and Yakwei. Among the constricted races, the larvae of SKAUR-1 showed significantly higher levels of free amino acid followed by SKUAST-28, NB4D2,
SKUAST-13 and CSR4.
Despite fluctuations, metabolic homeostatic controls restrict abnormal rise and drop in
haemolymph sugar levels during actively feeding larval and quiescent pupal stages in the
silkworm life cycle. The glucose levels showed a significant linear decrease from 0 to 7 th day in
the 5th instar larvae in all the races. The carbohydrate levels for the entire 5th instar larval stage
were relatively higher in SKAU-R-6 than in SKUAST-31, Dun6, SH6, CSR5 and Yakwei. The
larvae of SKAU-R-1 showed significantly higher mean levels of carbohydrate followed by
NB4D2, SKUAST-28, SKUAST-13 and CSR4 among the constricted races. The lipid levels in
haemolymph were relatively lower at pre-moult and 4th moult larval stages in all the constricted
races in both seasons but the levels showed a sharp increase upon resumption of feeding in 5th
instar larvae. The lipid levels of haemolymph were found to be significantly lower in pupal stage
when compared to haemolymph protein levels of
5th instar larvae. Male pupae showed
significantly higher lipid levels than female pupae in all the races during spring and summer
seasons.
The larval weight of oval races irrespective of seasons was found to be significantly
higher in SKAU-R-6 followed by SKUAST-31, SH6, Doon6, CSR5 and Yakwei. Among the
constricted races, the larval weight was significantly higher in SKAU-R-1 followed by NB4D2,
SKUAST-28, SKUAST-13 and CSR4. The effective rate of rearing (ERR) of all the races was
found to be significantly higher during spring than in summer season. Among the oval races of
silkworm, the ERR was higher in SKAU-R-6 followed by SKUAST-31, SH6, Dun6, Yakwei,
and CSR5. The ERR was significantly higher in SKAU-R-1 followed by NB4D2, SKUAST-28,
SKUAST-13 and CSR4 among the constricted races. Te cocoon weight among the oval races
was found to be significantly higher in SKUAST-31 followed by SKAU-R-6, SH6, Dun6, CSR5
and Yakwei. The cocoon weight of all the constricted races was found to be significantly higher
in NB4D2, followed by SKUAST-28, SKAU-R-1, SKUAST-13 and CSR-4. In SKAU-R-6,
significantly higher increase in shell weight was observed followed by SKUAST-31, SKAU-R-6,
SH6, Dun6, Yakwei and CSR5. Among the constricted races, the shell weight was found to be
significantly higher in SKAU-R-1 followed by SKUAST-28, NB4D2, SKUAST-13 and CSR4.
The filament length among the oval races was relatively higher in SKAU-R-6 followed by
SKUAST-31, SH6, Dun6, Yakwei and CSR5.
The levels of the biochemical constituents in haemolymph such as protein, free amino
acid, glucose, carbohydrate and lipids also varied significantly when the three selected silkworm
races viz. SKAU-R-1, SH6 and NB4D2 were reared on different varieties of mulberry namely
Ichinose (control), Goshoerami (uniformly the best), and Kokuso-20 (least productive). The free
amino acid, protein and carbohydrate content in the leaf of these three varieties were found to be
higher in spring than in summer season. Furthermore, significant changes in the biochemical
constituents were also observed in the same variety at different maturity levels and seasons. The
free amino acid and protein levels of all the maturity levels of the leaf were highest in
Goshoerami variety followed by Ichinose and Kokuso-20. The free amino acid and protein levels
in all the three varieties were relatively high in tender leaf followed by medium and coarse leaf.
The protein levels in the larvae fed with Goshoerami variety were relatively higher than the
levels of protein in the larvae fed with Ichinose and Kokuso-20.
A significant increase in the haemolymph proteins, free amino acids, glucose,
carbohydrates and lipids were observed in SKAU-R-1 fed on Goshoerami followed by Ichinose
and Kokuso-20. There was a significant decrease in haemolymph biochemical constituents in all
the races during both seasons in the order of Kokuso-20> Ichinose> Goshoerami. A significant
increase in the larval weight was observed in SKAU-R-1, NB4D2 and SH6 on Goshoerami
variety followed by Ichinose and Kokuso-20 during spring and summer season. Irrespective of
the seasons, the ERR of all the races was higher on Goshoerami followed by Ichinose and
Kokuso-20. The highest ERR was observed in SKAU-R-1 followed by NB4D2 and SH6. The
mean pupation rate of all the races was relatively higher on Goshoerami variety than on Ichinose
and Kokuso-20. The larvae of SKAU-R-1 showed a maximum mean pupation rate followed by
NB4D2 and SH6. Also, the cocoon and post-cocoon parameters of all the three silkworm races
were relatively more on Goshoerami variety followed by Ichinose and Kokuso-20.
The results of the present investigation demonstrate changes in the levels of protein, free
amino acid, glucose, total carbohydrate and lipids in haemolymph of oval and constricted races.
The changes in the chemical composition of haemolymph reflect tissue specific changes in
different developmental stages and in response to seasons in the races of Bombyx mori under
study and revealed that, SKAU-R-6, SKUAST-31, SH6, NB4D2, SKAU-R-1 and SKUAST-28
displayed better physiological compensatory mechanisms in response to exposure to higher
temperatures and, therefore, are more suitable for rearing in summer season of Kashmir in
addition to spring season than the productive CSR4, CSR5, Dun6 and Yakwei races which have
poor ability of acclimation to higher temperature. All these races qualify for higher cocoon
productivity with superior economic parameter for spring as well as summer seasons of Kashmir.