Characterization of Halyomorpha halys TAR1 reveals its involvement in (E)-2-decenal pheromone perception

In insects, 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. 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 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 an RNAi approach, topically delivered HhTAR1 dsRNA induced a 50% downregulation in gene expression after 24 h in H. halys 2nd instar nymphs. An innovative behavioural assay revealed that HhTAR1 RNAi-silenced 2nd instar nymphs were less susceptible to the alarm pheromone component (E)-2 decenal as compared with controls. These results provide critical information concerning the role of TAR1 in olfaction regulation, especially alarm pheromone reception, in H. halys. Furthermore, considering the emerging role of TAR1 as target of biopesticides, this work opens the way for further investigation on innovative methods for controlling H. halys.

Automated summary

In this study, the researchers investigated the molecular and functional profile of the HhTAR1 gene in the pest Halyomorpha halys, focusing on its role in olfactory functions. They found that HhTAR1 is primarily expressed in the adult brain and antennae, and also in early developmental stages. Through RNAi approach, they were able to reduce HhTAR1 expression and observed a decreased sensitivity to alarm pheromones in the treated nymphs. These results provide important insights into the role of TAR1 in olfaction regulation and suggest potential innovative methods for pest control.