RNAi-Mediated Interference with EonuGR1 Affects the Recognition of Phenylacetaldehyde by Empoasca onukii Matsuda (Hemiptera: Cicadellidae)

Empoasca onukii Matsuda is a primary pest of the tea plant Camellia sinensis (L.) O. Ktze that severely influences the production and quality of tea products. Gustatory receptors (GRs) are an indispensable part of the E. onukii chemosensory machinery as members of the G-protein coupled receptor family. Insect odor and gustatory receptors are consumingly sensitive and selective sensory receptors to search for foraging, mates, and spawning sites. In this study, the gustatory receptor EonuGR1 was cloned and analyzed bioinformatically, and the expression levels of EonuGR1 in diverse tissues of E. onukii were tested via qRT-PCR. The behavioral response of E. onukii to volatile compounds was determined via RNA interference and Y-tube olfactometer assays to investigate the role of EonuGR1 in the olfactory recognition of E. onukii. The coding sequence length of EonuGR1 was 1062 bp, and the length of the protein encoded by EonuGR1 was 40.52 kD. The highest interference efficiency was observed after 3 h of dsEonuGR1 treatment via root soak treatment. Moreover, the response rates to phenylacetaldehyde at concentrations of 10 and 0.1 mu L/mL were significantly downregulated in E. onukii. The responses to phenylacetaldehyde at concentrations of 10 and 100 mu L/mL showed a significant decrease after dsEonuGR1 treatment for 12 h in E. onukii. In conclusion, EonuGR1 was highly expressed in the abdomen and functioned in olfactory recognition of the tea plant volatile phenylacetaldehyde by E. onukii. Overall, EonuGR1 has the potential as a gene target for the design of effective control strategies against E. onukii.