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
Karnataka State Sericulture Research and Development Institute,
Thalaghattapura, Bangalore - 560 062, Karnataka, INDIA

KEY WORDS
Silk gland 
SGTSI 
Productivity






Received on: 23.02.2007

Accepted on: 17.06.2007



*Corresponding
 Author

ABSTRACT

The 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.