Effects of Methoprene on Cocoon Parameters of Muga Silk Worm Antheraea Assamensis Helfer

The present study was carried out to determine the effects ofjuvenile hormone analogue (JHA) methoprene on the cocoon parameters of the muga silkworm Antheraea assamensis Helfer, with an understanding of insect growth regulators used for increased silk production. Som (Persea bombycina) plants with quality foliage were sprayed with 0.01 and 0.10 ppm doses of analytical grade liquid Methoprene (purity, 99.1%) separately. 48 hr old fifth instar larvae post fourth molt were allowed to feed on them forming treatment groups. Positive and negative control groups were also maintained. Administration of 0.01 ppm influenced the prolongation of 5^th instar larval period by four days that resulted in maximum cocoon weight (5.61 g), shell weight (0.45 g), non-breakable filament length (275.81 m), reelability % (66.67%), raw silk (6.92%), tensile strength (623.08 mpa) and elongation (45.18%) with a decreased denier (4.85 d) which were highly significant. The 0.01 ppm dose of methoprene also elevated the sericin content as well as the fibroin content of cocoons significantly.