Abstract

Juvenile hormone analogues (JHA s) are known to prolong larval life in insects, and these have been tried for the improvement of silk production in the silkworm,Bombyx mori (L). In the cocoons and silk from 5^th  instar B. mori treated with selected doses of methoprene and fenoxycarb, quantitative parameters like cocoon weight, shell weight, shell percentage, filament length and denier followed by qualitative characters of the silk like non-breakable filament length, reelability, winding capacity, tenacity, elongation percentage, cohesiveness, sericin and fibroin contents were determined. The cocoon from 1.0 mg methoprene and 3.0 fg/larvae treated on days one and two showed improved quantitative characters of cocoons followed by qualitative characters of the silk over the control.  The use of juvenile hormone like methprene and fenoxycarb during summer season will help to get improved cocoon yield.

Key words: Silkworm, methoprene, fenoxycarb, cocoons and silk.