Palli S R., Brownwright A J., Davis C N., Tomkins W L., MacDonald A, Retnakaran A
Natural Resources Canada, Canadian Forest Service, 1219 Queen Street East, PO Box 490, Sault Ste Marie, Canada
J Insect Physiol. 1997 Feb 19;43(1):55-68. doi: 10.1016/s0022-1910(96)00062-5.
Force feeding of RH-5992 (Tebufenozide), a non-steroidal ecdysone agonist to newly moulted sixth instar larvae of the spruce budworm, Choristoneura fumiferana, (Lepidoptera: Tortricidae) initiates a precocious, incomplete moult. Within 6h post treatment (pt) the larva stops feeding and remains quiescent. Around 12hpt, the head capsule slips partially revealing an untanned new head capsule that appears wrinkled and poorly formed. By 24hrpt, the head capsule slippage is pronounced and there is a mid-dorsal split of the old cuticle in the thoracic region but there is no ecdysis. The larva remains moribund in this state and ultimately dies of starvation and desiccation. The temporal sequence of the external and internal changes of the integument were studied using both scanning and transmission electron microscopy. Within 3hpt, there is hypertrophy of the Golgi complex indicating synthetic activity and soon after, large, putative ecdysial droplets are seen. Within 24h, a new cuticle that lacks the endocuticular lamellae is formed. The formation of the various cuticular components, the degradation of the old cuticle and changes in the organelles of the epidermal cells of the mesothoracic tergite are described. The difference between the natural moult and the one induced by RH-5992 are explained on the basis of molecular events that take place during the moulting cycle. The persistence of this ecdysone agonist in the tissues permits the expression of all the genes that are up-regulated by the presence of the natural hormone but those that are turned on in the absence of the hormone are not expressed.
对云杉芽卷叶蛾（Choristoneura fumiferana，鳞翅目：卷蛾科）新蜕皮的六龄幼虫强制喂食非甾体蜕皮激素激动剂RH - 5992（虫酰肼）会引发早熟的不完全蜕皮。处理后（pt）6小时内，幼虫停止取食并保持静止。处理后约12小时，头壳部分脱落，露出一个未鞣化的新头壳，看起来有皱纹且发育不良。到处理后24小时，头壳脱落明显，胸部区域的旧表皮出现背中裂，但没有蜕皮。幼虫在这种状态下仍然垂死，最终死于饥饿和脱水。使用扫描电子显微镜和透射电子显微镜研究了体表的外部和内部变化的时间顺序。处理后3小时内，高尔基体肥大，表明有合成活性，不久后可见大的假定蜕皮液滴。24小时内，形成了一个缺乏内表皮层的新表皮。描述了中胸背板各种表皮成分的形成、旧表皮的降解以及表皮细胞细胞器的变化。根据蜕皮周期中发生的分子事件解释了自然蜕皮与RH - 5992诱导的蜕皮之间的差异。这种蜕皮激素激动剂在组织中的持续存在允许表达所有因天然激素存在而上调的基因，但在没有激素时开启的基因则不表达。
