Influence of Juvenile Hormone Analogue, Methoprene on the Biochemical Changes and Economic Characters of Silkworm

The influence of methoprene on the changes in trehalose,glycogen content and economic characters of silkworm were studied in CSR2 x CSR4 (Bivoltine x Bivoltine), and PM x CSR2 (Multivoltine x Bivoltine) hybrids. Application of methoprene caused significant (P< 0.05) increase in trehalose and glycogen contents, both in haemolymph and fat body tissues. The increase in trehalose was about 48% and 37% in haemolymph after 72 hrs of treatment in CSR2 x CSR4 and PM x CSR2 respectively. In the fat body 25 & 26 % increased trehalose content was observed after 96 hours of treatment in CSR2 x CSR4 and PM x CSR2 respectively. Significant (P< 0.05) increase in glycogen content also observed between treated and control hybrids in both tissues. Administration of methoprene (JH) also influenced the prolongation of 5 instar larval period by 24 hours in PM x CSR2 and 30 hours in CSR2 x CSR4 and resulted in significant increase in the cocoon weight (6.45 and 10.30%), shell weight (9.25 and 14.53%) and shell percentage (2.56 and 3.80%) in both the hybrids. Thus the methoprene administration prolonged the larval period and increased the cocoon characters in silkworm hybrids. The differential behaviour of trehalose and glycogen content suggested that these disaccharides might play distinct physiological roles during course of development.