In Drosophila melanogaster, ecdysis triggering hormone (ETH) is the key factor triggering ecdysis behaviour and promoting trachea clearance. However, whether ETH plays the dual roles in non‐dipteran insects is unknown. In this survey, we found that Ldeth mRNA levels were positively correlated with circulating 20‐hydroxyecdysone (20E) titers in Leptinotarsa decemlineata. Ingestion of an ecdysteroid agonist halofenozide or 20E stimulated the transcription of Ldeth, whereas RNA interference (RNAi) of ecdysteroidogenesis (LdPTTH or LdSHD) or 20E signalling (LdEcR, LdUSP or LdFTZ‐F1) genes inhibited the expression, indicating ETH acts downstream of 20E. RNAi of Ldeth at the final instar stage impaired pupation. More than 80% of the Ldeth‐depleted beetles remained as prepupae, completely wrapped in the old larval cuticles. These prepupae became withered, dried and darkened gradually, and finally died in soil. The remaining Ldeth hypomorphs pupated and emerged as abnormal adults, bearing smaller and wrinkle elytrum and hindwing. Moreover, the tracheae in the Ldeth hypomorphs were full of liquid. We accordingly proposed that the failure of trachea clearance disenabled air‐swallowing after pupa–adult ecdysis and impacted wing expansion. Our results suggest that ETH plays the dual roles, initiation of ecdysis and motivation of trachea clearance, in a coleopteran.

中文翻译：

---

蜕皮触发激素对于 Leptinotarsa decemlineata 的幼虫-蛹-成虫转化至关重要

在黑腹果蝇中，蜕皮触发激素（ETH）是触发蜕皮行为和促进气管清除的关键因素。然而，ETH是否在非双翅目昆虫中发挥双重作用尚不清楚。在这项调查中，我们发现Ldeth mRNA 水平与Leptinotarsa decemlineata 中循环的 20-羟基蜕皮激素 (20E) 滴度呈正相关。摄入蜕皮激素激动剂卤苯酰肼或 20E 刺激了Ldeth的转录，而蜕皮激素生成的RNA 干扰（RNAi）（LdPTTH或LdSHD）或 20E 信号（LdEcR、LdUSP或LdFTZ-F1）) 基因抑制表达，表明 ETH 作用于 20E 的下游。Ldeth在最后龄期的RNAi损害了化蛹。超过 80% 的Ldeth耗尽的甲虫仍然是预蛹，完全包裹在旧的幼虫角质层中。这些预蛹逐渐枯萎、干燥和变黑，最后死在土壤中。其余的Ldeth 亚型化蛹并以异常成虫的形式出现，带有较小且有皱纹的鞘翅和后翅。此外，Ldeth 中的气管亚形体充满了液体。我们因此提出，气管间隙的失败导致蛹 - 成虫蜕皮和影响翅膀扩张后无法吞咽空气。我们的结果表明 ETH 在鞘翅目中扮演着双重角色，蜕皮的开始和气管清除的动机。