The spruce bark beetle, Ips typographus, is an invasive forest pest that occurs across Eurasia. To further understand the mechanism of insect–host chemical communication and the feeding choices of adult I. typographus, we examined the sensilla on the antennae and mouthparts of I. typographus using scanning electron microscopy. No sexual dimorphism in sensilla type or distribution was observed. Ten subtypes of antennal sensilla were identified: sensilla trichodea Types I–III (TR¹, TR², and TR³); sensilla chaetica Types I and II (CH¹ and CH²); sensilla basiconica Types I–III (BA¹, BA², and BA³); sensilla coeloconica (CO); and Böhm sensilla (BS). BA² were the most abundant among the antennal sensilla in both sexes. Thirteen mouthpart sensilla subtypes were observed: sensilla trichodea Types I–IV (TR¹, TR², TR³, and TR⁴); sensilla chaetica Types I–III (CH¹, CH², and CH³); sensilla digitiformia (DI); sensilla basiconica Types I–II (BA¹ and BA²); and sensilla styloconica Types I–III (ST¹, ST², and ST³). Among these, TR⁴ were the most abundant in both sexes. The apex of each maxillary and labial palp carried the same sensilla (BA², ST¹, ST², and ST³), although the apex of the maxillary palp contained more total sensilla. The functional roles of each sensilla type are discussed based on their external structure and distribution. The results provide a theoretical basis for further studies on the olfactory and feeding behaviors and electrophysiology of adult I. typographus.

中文翻译：

---

成年云杉树皮甲虫 Ips Typgraphus（鞘翅目：Curculionidae）的触角和口器上的感觉器

云杉树皮甲虫Ips Typgraphus是一种发生在欧亚大陆的入侵森林害虫。进一步了解昆虫-宿主化学通讯的机制和成虫的取食选择I . 印刷术，我们检查了I .的触角和口器上的感觉器。使用扫描电子显微镜的印刷术。未观察到感受器类型或分布的性别二态性。确定了十种触角感受器亚型：毛滴虫感受器 I-III 型（TR ¹、TR ²和 TR ³）；Sensilla chaetica I 型和 II 型（CH ¹和 CH ²）；基本感器 I-III 型（BA¹、BA ²和 BA ³ )；腔肠感受器 (CO); 和 Böhm 感器 (BS)。BA ²在两性的触角感受器中含量最高。观察到了 13 种口器感受器亚型：毛滴虫感受器 I-IV 型（TR ¹、TR ²、TR ³和 TR ⁴）；Sensilla chaetica Types I–III (CH ¹ , CH ² , and CH ³ ); 数字感器 (DI); 基本感器 I-II 型（BA ¹和 BA ²）；和柱状感器 I-III 型（ST ¹、ST ²和 ST ³）。其中，TR ⁴在两性中最丰富。每个上颌和唇触的顶端都带有相同的感受器（BA ²、ST ¹、ST ²和 ST ³），尽管上颌触须的顶端包含更多的总感受器。根据它们的外部结构和分布讨论了每种感觉器类型的功能作用。研究结果为进一步研究I . 排版。