Table_2_Honey Bee Parasitic Mite Contains the Sensilla-Rich Sensory Organ on the Foreleg Tarsus Expressing Ionotropic Receptors With Conserved Functions.XLSX

Honey bee parasitic mites (Tropilaelaps mercedesae and Varroa destructor) detect temperature, humidity, and odor but the underlying sensory mechanisms are poorly understood. To uncover how T. mercedesae responds to environmental stimuli inside a hive, we first identified the sensilla-rich sensory organ on the foreleg tarsus. The organ appeared to correspond to Haller’s organ in ticks and contained four types of sensilla, which may respond to different stimuli based on their morphology. We searched for differentially expressed genes between the forelegs and hindlegs to identify mRNAs potentially associated with the sensory organ. The forelegs were enriched with mRNAs encoding sensory proteins such as ionotropic receptors (IRs) and gustatory receptors, as well as proteins involved in ciliary transport. We also found that T. mercedesae IR25a and IR93a were capable of rescuing temperature and humidity preference defects in Drosophila melanogaster IR25a and IR93a mutants. These results demonstrate that the structures and physiological functions of ancient IRs have been conserved during arthropod evolution. Our study provides insight into the sensory mechanisms of honey bee parasitic mites, as well as potential targets for methods to control the most serious honey bee pest.

蜜蜂寄生螨（Tropilaelaps mercedesae 和 Varroa destructor）能够感知温度、湿度和气味，但其感官机制尚不明确。为了揭示 T. mercedesae 在蜂巢内部对环境刺激的响应机制，我们首先确定了位于前腿跗节上的富含感觉毛的感觉器官。该器官与蜱虫中的 Haller 肌官相对应，并含有四种类型的感觉毛，这些感觉毛可能根据其形态对不同的刺激作出反应。我们通过比较前腿和后腿之间的差异表达基因，以寻找可能与该感官器官相关的 mRNA。我们发现前腿富含编码离子型受体（IRs）和味觉受体等感觉蛋白，以及参与纤毛运输的蛋白。此外，我们还发现 T. mercedesae 的 IR25a 和 IR93a 能够拯救黑腹果蝇 IR25a 和 IR93a 突变体的温度和湿度偏好缺陷。这些结果表明，古老的 IRs 的结构和生理功能在节肢动物进化过程中得到了保留。本研究揭示了蜜蜂寄生螨的感官机制，并为控制最严重的蜜蜂病虫害的方法提供了潜在的治疗靶点。