Table_1_Honey Bee Parasitic Mite Contains the Sensilla-Rich Sensory Organ on the Foreleg Tarsus Expressing Ionotropic Receptors With Conserved Functions.DOCX

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，但其内在的感官机制尚不明确。为了揭示T. mercedesae如何响应巢内环境刺激，我们首先在螯足上识别出富含感觉毛的感官器官，该器官似乎对应于蜱虫中的Haller器官，并含有四种不同类型的感觉毛，这些感觉毛可能根据其形态对不同的刺激产生反应。我们搜索了前足与后足之间差异表达的基因，以识别与感官器官相关的mRNA。前足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的mRNA。我们还发现，T. mercedesae的IR25a和IR93a能够挽救果蝇 melanogaster 中IR25a和IR93a突变体的温度和湿度偏好缺陷。这些结果证明了古老IRs的结构和生理功能在节肢动物进化过程中得到了保留。本研究为揭示蜜蜂寄生螨的感官机制以及控制最严重的蜜蜂害虫的方法提供了潜在靶点。