Temporal organization of endocrine events underlying larval-pupal metamorphosis in the silkworm, Bombyx mori

Sakurai, Shigeki

doi:10.1016/0022-1910(84)90051-9

Cited by 86 publications

(33 citation statements)

References 26 publications

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“…Attainment of a critical weight for moult initiation in larvae and PTTH release is also reported for several species of Lepidoptera (Safranek & Williams, 1984;Sehnal, 1985), Similar observations on the timing of ecdysis of larvae are reported for Samia cynthia ricini kept under various light-dark conditions (Fujishita & Ishizaki, 1981). Larval moulting is induced by a single peak of ecdysone (Sakurai, 1983(Sakurai, , 1984Okuda et al, 1985, Gilbert et al, 1996. This is confirmed by the present study, because prior to moulting, the ecdysone titer peaked in penultimate instars of both NDD and DD larvae.…”

Section: Endocrine Eventssupporting

confidence: 90%

“…Before the onset of wandering in the ultimate instar, a large peak in the 20-HE titer is reported (Fujishita & Ishizaki, 1982;Richards et al, 1987) and PTTH has to be released for pupation to occur on schedule (Truman & Riddiford, 1974;Gilbert et al, 1981). Each PTTH release is followed by a corresponding increase in 20-HE titer (Bollenbacher et al, 1975;Sakurai, 1984) and second release of PTTH is required for the larval-pupal transformation (Safranek & Williams, 1980;Sakurai, 1984). Similar results were also obtained in the present study as the two large peaks of 20-HE were recorded in 5 th instar larvae on day 8 of the feeding period and day 4 of post-feeding period in NDD and on day 14 of feeding period of DD larvae in A. mylitta which confirms the findings of the above authors for other insects.…”

Section: -Hydroxyecdysone Titermentioning

confidence: 99%

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Endogenous 20-hydroxyecdysone levels in the haemolymph of non-diapause-destined and diapause-destined generations of tasar silkworm, Antheraea mylitta (Lepidoptera: Saturniidae) and associated developmental changes

Kumar¹,

Subrahmanyam²,

Sharan³

et al. 2008

Eur. J. Entomol.

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Abstract.A complete profile of the 20-hydroxyecdysone (20-HE) titer, development and endocrine events from 1 st instar to pupation of the larvae of non-diapause-destined (NDD) and diapause-destined (DD) tasar silkworm, Antheraea mylitta Drury (Lepidoptera: Saturniidae) was studied. Diapause is induced by short days of 11 hr photophase coupled with 24°C prevailing in SeptemberNovember. Diapausing pupae produce adults in July ( 12h light, 26°C) and one generation is completed by August. The growth rate during the course of development of larval instars decreases and instar durations are inversely related to the body weight at the time of initiation of a larval instar. A growth compensation mechanism operates during the development of the larval instars. The growth rate was higher in early instars (1 st to 4 th ) in both generations. The DD larvae complete the final instar in 16 days followed by a spinning stage of 13 days. The NDD larvae complete the final larval instar in 9 days followed by spinning stage of 6 days and spend 14 days in the pupal stage. The signal to release the prothoracicotropic hormone (PTTH) is related to critical body weight of larvae. From 1 st to 4 th instar, pre-ecdysial peaks of 20-HE were recorded in both NDD and DD generations. The programme for undergoing diapause was initiated during 3 rd instar and induced by a sudden decrease in the level of 20-HE in the DD generation. Two peaks of 20-HE are required for the larval-pupal transformation, first at the wandering stage and the second at cuticle formation.

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Section: Endocrine Eventssupporting

confidence: 90%

Section: -Hydroxyecdysone Titermentioning

confidence: 99%

Endogenous 20-hydroxyecdysone levels in the haemolymph of non-diapause-destined and diapause-destined generations of tasar silkworm, Antheraea mylitta (Lepidoptera: Saturniidae) and associated developmental changes

Kumar¹,

Subrahmanyam²,

Sharan³

et al. 2008

Eur. J. Entomol.

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“…1, 14-16 (2008) Anti-juvenile hormone agents 15 tion. 19) The (S )-enantiomer of KF-13 as well as ETB prolonged the duration of the instar and delayed the onset of cocoon spinning when applied to 5th-instar larvae, while the (R)-enantiomer did not show any effect. The activity of the racemic mixture KF-13 was less than that of KF-13(S).…”

Section: Jh Activity Of Ethyl 4-(2-substituted Hexyloxy)benzoatesmentioning

confidence: 92%

Synthesis and biological activity of novel anti-juvenile hormone agents

et al. 2008

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Ethyl 4-[2-(tert-butylcarbonyloxy)butoxy]benzoate (ETB) is a partial juvenile hormone (JH) antagonist which targets larval epidermis. We converted ETB to ethyl 4-(2-substituted alkyloxy)benzoates. These compounds induced precocious metamorphosis in the silkworm, Bombyx mori, which is a clear sign of JH deficiency, and their activity was completely counteracted by the simultaneous application of a JH agonist, methoprene. Among these novel compounds, ethyl 4-(2-benzylhexyloxy)benzoate (KF-13) showed high precocious metamorphosis-inducing activity at low doses, but its activity decreased with increasing dose, probably due to their JH-like activity. KF-13 is an enantiomeric compound. The (S)-enatiomer of KF-13 was more active than the (R)-enantiomer at low doses, but at high doses the activity was reversed (RϾS). Hemolymph JH esterase activity, which is indispensable for the initiation of pupation in normal last-instar larvae, was induced in 4th-instar larvae by treatment with KF-13. 2-(6-Methyl-3-pyridyloxy)hexyl and 2-phenoxyhexyl analogs showed JH activity when topically applied to allatechtomized 4th-instar larvae.

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“…Bombyx eggs of a racial hybrid, Kinshu × Showa, were obtained from Ueda Sanshu (Ueda, Japan), and larvae were reared on an artificial diet (Silkmate II, Nihon Nousan Kogyo, Yokohama, Japan) under a 12 h light/12 h dark photoperiod at 25°C (Sakurai, 1984). Ages were counted in days, with a photophase followed by a scotophase.…”

Section: Experimental Animals and Hormonementioning

confidence: 99%

Identification of 20-Hydroxyecdysone-Inducible Genes from Larval Brain of the Silkworm, Bombyx mori, and Their Expression Analysis

et al. 2012

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Temporal organization of endocrine events underlying larval-pupal metamorphosis in the silkworm, Bombyx mori

Cited by 86 publications

References 26 publications

Endogenous 20-hydroxyecdysone levels in the haemolymph of non-diapause-destined and diapause-destined generations of tasar silkworm, Antheraea mylitta (Lepidoptera: Saturniidae) and associated developmental changes

Endogenous 20-hydroxyecdysone levels in the haemolymph of non-diapause-destined and diapause-destined generations of tasar silkworm, Antheraea mylitta (Lepidoptera: Saturniidae) and associated developmental changes

Synthesis and biological activity of novel anti-juvenile hormone agents

Identification of 20-Hydroxyecdysone-Inducible Genes from Larval Brain of the Silkworm, Bombyx mori, and Their Expression Analysis

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