Precocious Metamorphosis Induced by an Anti-Juvenile Hormone Compound Applied to 3rd Instar Silkworm Larvae, Bombyx mori L. (Lepidoptera : Bombycidae)

Abstract

Induction of precocious metamorphosis in silkworm larvae, Bombyx mori by an anti-JH compound, 1-citronellyl-5-phenyl-midazole (KK-22), was investigated in relation to the application time of 3rd instar. Sensitive stage to KK-22 was in late 3rd instar. Most of the precocious pupation was observed in the 4th (penultimate) instar. Successive application with KK-22 prevented the 3rd instar larvae from molting into the next 4th instar and finally induced them to precocious pupation within the same 3rd (antepenultimate) instar. Some relationships were observed among the induction of precocious metamorphosis, the prolongation of 3rd instar, and the increase in body weight of 3rd instar larvae at molting. Most 3rd instar larvae with feeding periods prolonged by 2 days or more and having 70% or more increased body weight at 3rd molting time experienced precocious pupation at the subsequent 4th instar.