In insects, the tyramine receptor 1 (TAR1) has been shown to control several physiological functions, including olfaction. We investigated the molecular and functional profile of the Halyomorpha halys type 1 tyramine receptor gene (HhTAR1) and its role in olfactory functions of this pest. Molecular and pharmacological analyses confirmed that the HhTAR1 gene codes for a true TAR1. The RT-qPCR analysis revealed that HhTAR1 is expressed mostly in adult brain and antennae as well as in early development stages (eggs, 1st and 2nd instar nymphs). In particular, among the antennomeres that compose a typical H. halys antenna, HhTAR1 was more expressed in flagellomeres. Scanning electron microscopy (SEM) investigation revealed the type and distribution of sensilla on adult H. halys antennae: both flagellomeres appear rich in trichoid and grooved sensilla, known to be associated with olfactory functions. Through a RNAi approach, topically delivered HhTAR1 dsRNA induced a 50 % gene downregulation after 24 h in H. halys 2nd instar nymphs. An innovative behavioral assay revealed that HhTAR1 RNAi-silenced 2nd instar nymphs were less susceptible to the alarm pheromone component (E)-2 decenal as compared to control. These results provide critical information concerning the TAR1 role in olfaction regulation, especially alarm pheromone reception, in H. halys. Furthermore, considering the emerging role of TAR1 as target of biopesticides, this work paves the way for further investigation on innovative methods for controlling H. halys.

中文翻译：

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酪胺受体驱动臭虫Halyomorpha halys对（E）2-癸烯的嗅觉反应

在昆虫中，酪胺受体1（TAR1）已被证明可控制多种生理功能，包括嗅觉。我们调查了Halyomorpha halys 1型酪胺受体基因（HhTAR1）的分子和功能概况及其在该害虫的嗅觉功能中的作用。分子和药理学分析证实，HhTAR1基因编码真正的TAR1。RT-qPCR分析表明，HhTAR1主要在成年大脑和触角以及早期发育阶段（卵，第一龄和第二龄若虫）表达。特别是在构成典型的H. halys天线的触角动物中，HhTAR1在鞭毛虫中表达更多。扫描电子显微镜（SEM）研究揭示了成年H. halys触角上的感官的类型和分布：鞭毛均富含毛线虫和带沟纹的感官，已知与嗅觉功能有关。通过RNAi方法，在H. halys二龄若虫中24 h后，局部递送的HhTAR1 dsRNA诱导了50％的基因下调。创新的行为分析显示，与对照组相比，HhTAR1 RNAi沉默的第二龄若虫若不受到警报信息素成分（E）-2的影响，则更不敏感。这些结果提供了有关TAR1在H. halys中嗅觉调节特别是警报信息素接收中的重要信息。。此外，考虑到TAR1作为生物农药目标的新兴作用，这项工作为进一步研究控制H. halys的创新方法铺平了道路。