The Bioscan, 2 (4): 297-299, 2007 An International Quarterly Journal of Life Sciences web site: www.thebioscan.in
SILK GLAND SOMATIC INDEX IN SOME PURE RACES OF BOMBYX MORI L.
P. B. VIJAYAKUMAR, S. R. KATTI*, H. VENKATESH AND B. M. SEKHARAPPA
KEY WORDS Silk gland SGTSI Productivity Received on: 23.02.2007 Accepted on: 17.06.2007 *Corresponding Author
silk produced by Bombyx mori is synthesized in the silk gland,
the growth of which indirectly provides clue on productivity. The present
study is an attempt to draw correlation between silk gland and body weight
which is expressed as Silk gland Somatic Index (SGTSI). Tweleve races
including 2 multivoltine and 10 bivoltine were used for the study. The
SGTSI index was assessed during fifth instar of larval stage being the
most productive stage. It is observed that the SGTSI varies with races.
More productive races showed high SGTSI while the less productive races
recorded lower SGTSI among the bivoltines studied. An index of 24-25 percent
was recorded in most of the productive bivoltine races and lower for less
productive races like NP2 (Shell ratio (SR) 17.5%) and KS01 (SR16.27%)
where the index recorded is around 22 percent. Among the bivoltine the
highest SGTSI was recorded for CSR2 (28.5%) and lowest SGTSI is observed
in NP2(19.4) eliciting positive correlation between SGTSI and shell ratio
among the bivoltines. It was also seen that SGTSI is found to be more
in males than females as revealed in the sex limited races HDO and HND.
The study shows that SGTSI can be a useful trait for breeding and nutritional
studies. The findings are discussed in the paper.