Abstract: 【Aim】To elucidate the repellent activities of three plant-derived compounds neochamaejasmine A, thymol and azadirachtin against adult Tribolium confusum and their effects on its olfaction-related genes. 【Methods】 The relative electroantennogram (EAG) response values of T. confusum adults to 0.005, 0.05, 0.5, 5 and 50 μg/μL neochamaejasmine A, thymol and azadirachtin were measured. The olfactory behavior responses of T. confusum adults to neochamaejasmine A, thymol and azadirachtin at the concentrations of 0.5, 5 and 50 μg/μL were studied by Y-tube olfactometer. Impregnated filter paper method was used to determine the repellent rates of 20, 30, 40, 50 and 60 mg/L neochamaejasmine A, thymol and azadirachtin to T. confusum adults. Transcriptomes of the head of T. confusum adults treated with median lethal concentration (LC₅₀)(28.37 mg/L) neochamaejasmine A, LC₅₀(51.05 mg/L) thymol and LC₅₀(42.20 mg/L) azadirachtin were sequenced and comparatively analyzed using RNA-Seq. 【Results】The relative EAG response value of T. confusum adults was proportional to the concentrations of neochamaejasmine A, thymol and azadirachtin. At the maximum concentration of 50 μg/μL, neochamaejasmine A, thymol and azadirachtin resulted in the relative EAG response values of T. confusum adults of 1.61, 2.69 and 2.34 mV, respectively, and the selection rates of 86.48%, 73.89% and 78.33%, respectively. The repellent rates (74.67% and 80.82%, respectively) of 60 mg/L thymol to T. confusum adults were the highest at 2 and 4 h, and the repellent grades reached grades Ⅳ and Ⅴ, respectively. After treatment with thymol, neochamaejasmine A and azadirachtin, there were 569, 597 and 661 differentially expressed genes in the head transcriptomes of T. confusum adults, respectively, 412, 434 and 498 differentially expressed genes were annotated with GO function, respectively, and the differentially expressed genes were identified to 26, 33 and 32 KEGG pathways, respectively, compared with the control group. Thirteen, four and five olfaction-related genes with differential expression were found after treatment with thymol, neochamaejasmine A and azadirachtin, respectively. 【Conclusion】In this study, the repellent activities of the three plant-derived compounds to T. confusum adults were determined and the head transcriptome of T. confusum adults was sequenced. It is speculated that the differentially expressed genes may play an important role in T. confusum repelling the three plant-derived compounds.

Key words: Tribolium confusum, plant-derived compounds, repellent activity, transcriptome, differentially expressed genes, olfaction-related gene