The ladybird Harmonia axyridis is an insect that exhibits pupal attachment to plants, which facilitates development and environmental adaptation. The cremaster is highly specialized for this behavior. However, the underlying molecular regulation of the cremaster remains unclear; therefore, we performed experiments to investigate the transcriptional regulation of cremaster development. First, we examined the morphological structure of the cremaster to reveal its function in pupal attachment of H. axyridis. Next, we analyzed the Hox gene Ha-Abd-B using RNA interference (RNAi) to determine its function in regulating cremaster formation; Ha-Abd-B up-regulation promoted effective pupal attachment, whereas successful RNAi caused severe down-regulation of this gene, and pupae were unable to attach. Furthermore, successful RNAi and subsequent Ha-Abd-B down-regulation caused phenotypic changes in cremaster structure, including its complete disappearance from some individuals. Finally, we observed unique development of the cremaster and dynamic expression of Ha-Abd-B during pre-pupal development; consequently, we hypothesized that there was specific pre-pupal development of the cremaster. Overall, based on these results, the specialized cremasteric structure located on the posterior side of H. axyridis was determined to be a key organ for pupal attachment. Cremaster identification in H. axyridis is regulated by Ha-Abd-B and exhibits preferential development. Pupal attachment of H. axyridis reveals an environmental adaptation of this species; thus, this study and future molecular studies will help determine the role of Hox genes in regulation of insect attachment and further our understanding of the multiple functions of Hox genes.

中文翻译：

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Abdominal-B 调节 Harmonia axyridis cremaster 的结构和发育

瓢虫Harmonia axyridis是一种昆虫，它表现出对植物的蛹依附，促进发育和环境适应。提尸官对这种行为非常专业。然而，提睾的潜在分子调控仍不清楚。因此，我们进行了实验来研究提睾酮发育的转录调控。首先，我们检查了提睾丸的形态结构，以揭示其在H. axyridis蛹附着中的功能。接下来，我们使用 RNA 干扰 (RNAi)分析了Hox基因Ha-Abd-B，以确定其在调节提睾脂形成中的功能；哈-阿卜杜-B上调促进了有效的蛹附着，而成功的 RNAi 导致该基因的严重下调，并且蛹无法附着。此外，成功的 RNAi 和随后的Ha-Abd-B下调导致提睾脂结构的表型变化，包括其从某些个体中完全消失。最后，我们观察到了前蛹发育过程中提睾的独特发育和Ha-Abd-B 的动态表达；因此，我们假设提睾有特定的前蛹发育。总的来说，基于这些结果，位于H. axyridis后侧的特殊提睾结构被确定为蛹附着的关键器官。Cremaster 鉴定在H. axyridis受Ha-Abd-B调控并表现出优先发育。H. axyridis 的蛹附着揭示了该物种的环境适应性；因此，这项研究和未来的分子研究将有助于确定Hox基因在调节昆虫附着中的作用，并进一步了解Hox基因的多种功能。