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The tea green leafhopper, Empoasca vitis Gothe, is one of the most serious insect pests of tea plantations in mainland China. Over the past decades, this pest has been controlled mainly by spraying pesticides. Insecticide applications not only have become less effective in controlling damage, but even more seriously, have caused high levels of toxic residues in teas, which ultimately threatens human health. Therefore, we should seek a safer biological control approach. In the present study, key components of tea shoot volatiles were identified and behaviorally tested as potential leafhopper attractants. The following 13 volatile compounds were identified from aeration samples of tea shoots using gas chromatography-mass spectrometry (GC-MS): (E)-2-hexenal, (Z)-3-hexen-1-ol, (Z)-3-hexenyl acetate, 2-ethyl-1-hexanol, (E)-ocimene, linalool, nonanol, (Z)-butanoic acid, 3-hexenyl ester, decanal, tetradecane, β-caryophyllene, geraniol and hexadecane. In Y-tube olfactometer tests, the following individual compounds were identified: (E)-2-hexenal, (E)-ocimene, (Z)-3-hexenyl acetate and linalool, as well as two synthetic mixtures (called blend 1 and blend 2) elicited significant taxis, with blend 2 being the most attractive. Blend 1 included linalool, (Z)-3-hexen-1-ol and (E)-2-hexenal at a 1 : 1 : 1 ratio, whereas blend 2 was a mixture of eight compounds at the same loading ratio: (E)-2-hexenal, (Z)-3-hexen-1-ol, (Z)-3-hexenyl acetate, 2-penten-1-ol, (E)-2-pentenal, pentanol, hexanol and 1-penten-3-ol. In tea fields, the bud-green sticky board traps baited with blend 2, (E)-2-hexenal or hexane captured adults and nymphs of the leafhoppers, with blend 2 being the most attractive, followed by (E)-2-hexenal and hexane. Placing sticky traps baited with blend 2 or (E)-2-hexenal in the tea fields significantly reduced leafhopper populations. Our results indicate that the bud-green sticky traps baited with tea shoot volatiles can provide a new tool for monitoring and managing the tea leafhopper.

Electrical penetration graph (EPG) investigation showed that the secreting (E1) and sucking (E2) times of tea aphid stylet in tea phloem were much longer than that on non-host plants such as soybean and wheat. However, non-feeding wave (np) was shorter than that on soybean and wheat. Duration of both E1 and E2 of stylet in tea phloem of 1st leaf, bud, 4th leaf and tender stem occupied 30.2%, 22.3%, 9.2% and 8.2% of the total experimental time, respectively. E2 wave was accompanied by honeydew secretion, with a time lag. Tea aphid preferred the tender parts, in which amino acids and other nutritional components were very rich. While the stylet of hungry tea aphid was forced to pierce phlom of non-host plant (soybean or wheat), E1 and E2 waves were also produced, but the action of stylet could be disrupted by tea shoot volatile (10~(-6) V/V linalool, etc.) emitted near to the antennae. It was considered that before and under probing tea aphid made use of olfactory clues.