Abstract: 【Aim】 This study aims to clone odorant receptor (OR) genes in Apolygus lucorum and to assay their expression levels in different adult tissues and their electrophysiological responses to host plant volatiles, so as to provide the theoretical basis for understanding the mechanism of host plant recognition in A. lucorum. 【Methods】 Based on the sequencing and analysis of the antennal transcriptome of A. lucorum, the full-length sequences of eight OR genes with intact ORF were cloned by PCR. The expression levels of these genes in different adult tissues (antenna, head without antenna, thorax, abdomen, leg and wing) were detected by using qPCR. The electrophysiological responses of these ORs to 56 odor compounds were tested in Xenopus oocytes as a heterologous expression system using two-electrode voltage clamp recording. 【Results】 The full-length cDNA sequences of 8 OR genes AlucOR9, AlucOR16, AlucOR38, AlucOR53, AlucOR55, AlucOR56, AlucOR57 and AlucOR58 (GenBank accession no.: MN905538-MN905545)of A. lucorum were cloned. These ORs contain seven transmembrane domains, with the intracellular N-terminus and extracellular C-terminus, consistent with the typical characteristics of insect ORs. The qPCR results showed that all the eight OR genes were highly expressed in adult antennae and lowly expressed in all the other tissues of A. lucorum. Moreover, the expression of the other seven OR genes except AlucOR38 in the antennae showed significant differences between male and female. The results of two-electrode voltage clamp recording showed that only AlucOR57 responded to 15 odor compounds ［benzaldehyde, (-)-caryophyllene oxide, heptanal, (E)-2-hexenal, benzyl acetate, (1R)-(-)-myrtenal, 4-ethylbenzaldehyde, nonyl acetate, 3,7-dimethyl-3-octanol, tridecane, (E)-3-hexenol, butyl acrylate, butyl propionate, octyl acetate and amyl acetate］, while the other seven ORs did not respond to all the odor compounds tested. 【Conclusion】 AlucOR57 responds to partial odor compounds tested, suggesting that it might be involved in the recognition of host plant volatiles in A. lucorum. The other seven ORs fail to respond to all the tested odor compounds, and their
functions need further study.

Key words:  Apolygus lucorum, antennae, odorant receptor, electrophysiological response; qPCR, two-electrode voltage clamp