Analysis of precocious metamorphosis induced by application of an imidazole derivative to early third instar larvae of the silkworm, Bombyx mori

• Published in: Archives of insect biochemistry and physiology Vol. 36; no. 4; pp. 349 - 361
• Main Authors: Gu, S.H, Chow, Y.S
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 1997
• Subjects: BOMBYX MORI; CONTROL HORMONAL; CONTROLE HORMONAL; ecdysteroid levels; ECDYSTERONE; ESTEROIDES; HAEMOLYMPH; HEMOLINFA; HEMOLYMPHE; HORMONAL CONTROL; HORMONAS DE LA MUDA; HORMONAS JUVENILES; HORMONE DE MUE; HORMONE JUVENILE; HYDROPRENE; IMIDAZOLE; IMIDAZOLES; INHIBIDORES DESARROLLO INSECTOS; INSECT GROWTH REGULATORS; juvenile hormone; JUVENILE HORMONES; KK-42; LARVAE; LARVAS; LARVE; METAMORFOSIS; METAMORPHOSE; METAMORPHOSIS; MOULTING HORMONES; precocious metamorphosis; REGULATEUR CROISSANCE INSECTE; STEROIDE; STEROIDS
• ISSN: 0739-4462; 1520-6327
• DOI: 10.1002/(SICI)1520-6327(1997)36:4<349::AID-ARCH7>3.0.CO;2-M

When an imidazole derivative (KK-42) was applied to day 1 third instar larvae of the silkworm, Bombyx mori, 100% underwent precocious metamorphosis at the end of the fourth instar. Thus, the fourth instar becomes the last instar in these KK-42-treated larvae. The endocrine systems underlying the precocious metamorphosis were analyzed in the present study. Hydroprene application during the prolonged third instar after KK-42 treatment can prevent precocious metamorphosis, and the results showed dose-dependent and stage-specific effects. From analysis of the developmental changes in ecdysteroid levels in both KK-42-treated larvae and KK-42- and hydroprene-treated larvae, we conclude that changes in JH levels during the third larval instar can modify the secretion pattern of prothoracic glands and that during the next larval instar, very low ecdysteroid levels during the early stages of the presumptive last (fourth) larval instar are directly related to precocious metamorphosis