Characterization of Volatile Compounds from Tea Plants (Camellia sinensis (L.) Kuntze) and the Effect of Identified Compounds on Empoasca flavescens Behavior

The tea green leafhopper, Empoasca flavescens, is a major pest of tea Camellia sinensis (L.) Kuntze. Until recently, it has mainly been controlled by pesticides, but their use has led to high levels of toxic residues in plants, which threaten both the environment and human health. Therefore, a safer biological control approach is needed. Tea plants produce many volatile compounds, and different tea clones differ in their resistance to the pest. We explored the possibility that volatile compounds influence the resistance of tea. Here, we assessed the resistance of 15 clones of tea plants to the pest, the volatile compounds produced by the clones, and the effects of the compounds on E. flavescens behavior. Six clones were classified as resistant, eight as moderately susceptible, and one as susceptible. Fresh leaf samples from resistant and susceptible clones were analyzed using HS-SPME-GC-MS. Sesquiterpenes and monoterpenes were two major groups characterized, representing 30.15% and 26.98% of the total compounds, respectively. From our analysis, we conclude that 3-hexen-1-ol, 2,6-dimethyleneoct-7-en-3-one, humulene, beta-bourbonene, styrene, and benzaldehyde were important for the resistance and susceptibility of the clones. In a bioassay, E. flavescens were attracted to beta-ocimene and methyl salicylate, but avoided linalool compounds.