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BACKGROUND The tea green leafhopper, Empoasca flavescens is the most important pest in Chinese tea plantations. For decades its control has been executed almost exclusively through pesticide applications. A semiochemical‐based ‘push–pull’ strategy was tested on the leafhopper in the study. RESULTS The odors released from Tagetes erecta and Flemingia macrophylla significantly repelled and attracted leafhoppers, respectively. These volatile compounds (46 from T. erecta and 53 F. macrophylla) were identified and quantified via gas chromatography–mass spectometry (GC–MS) analysis. Y‐tube olfactometer assays indicated that thymol anisole, thymol and camphor had significant repellent effects on the leafhoppers, resulting in a ternary repellent blend at a 4:3:13 ratio. Cis‐3‐hexen‐1‐ol, cis‐3‐hexenyl acetate, nonanal and α‐farnesene were significantly attractive to the leafhoppers, making an attractant blend at a 17:4:1:1 ratio. In the field, the push–pull strategy with the repellent dispensers placed within the tea bushes and the attractant‐baited sticky traps hung 15 cm above the tea plants showed a significant control efficacy, reaching 69% and 55% at two and 14 days post‐treatment, respectively, similar to those in the insecticide control plots. Additionally, the leafhopper density in the push–pull intercropping plot was 63.2 leafhoppers/100 tea shoots/visit, much lower than those in the pull intercropping plot and nonintercropping plot. CONCLUSION Application of the push–pull strategy using both synthetic repellent and attractant, or intercropping T. erecta and F. macrophylla with tea plants, can effectively reduce the leafhopper population. This approach might have great potential as an environmentally safe control strategy against the leafhopper. © 2022 Society of Chemical Industry.

The tea aphid (Toxoptera aurantii Boyer de Fonscolombe) is an important tea plant pest insect worldwide. The parasitoid wasp, Aphelinus sp., is one of the most important natural enemies of the tea aphid in China. Unfortunately, Aphelinus sp. alone cannot effectively control the outbreaks of the aphid under natural conditions. In this study, 27 volatile compounds from tea aphid-injured tea shoots, tea flowers, aphid sex pheromones, or body rinses were selected and tested in Y-tube olfactometer assays to find potential attractants of the parasitoid wasp, Aphelinus sp. Based on the Y-tube assay results, the following three attractant mixtures were formulated and further tested in the field. Attractant-1 (HIPV-based) included trans-2-hexenal (10−6 g/ml), β-ionone (10−6 g/ml), allyl isothiocyanate (10−4 g/ml), trans-2-pentenal (10−2 g/ml), and jasmone (10−2 g/ml) at equal loading volume of their solutions. Attractant-2 (with aphid sex-pheromone and body rinse compounds) included nepetalactone (10−6 g/ml), 2,5-hexanedione (10−4 g/ml), benzaldehyde (10−2 g/ml), eicosane (10−2 g/ml), and heptadecane (10−2 g/ml) at equal loading volume of their solutions. Attractant-3 (partial combination of Attractant-1 and Attractant-2) included nepetalactone (10−4 g/ml), benzaldehyde (10−2 g/ml), jasmone (10−2 g/ml), trans-2-hexenal (10−6 g/ml), eicosane (10−2 g/ml), and heptadecane (10−2 g/ml) at equal loading volume of their solutions. Field trials showed that Attractant-3 was much more attractive to the parasitic wasps than Attractant-1 and Attractant-2. From late August to late September the controlled release of Attractant-3 effectively attracted Aphelinus sp. to parasitize and colonize the aphid populations in the treated tea plantations, resulting in a progressive decrease of the tea aphid abundances/populations in the fall. The continued enhanced parasitism of overwintered aphids by Aphelinus sp. further reduced this population during the next spring tea harvest season. This approach may present an environmentally sound, non-insecticidal control tactic against tea aphids using synthetic semiochemicals.

The phthalate esters (PAEs) have become ubiquitous pollutants. In the present work, we investigated their pollution on teas. Dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DiBP), di-n-butyl phthalate (DBP), and di-(2ethyl) hexyl phthalate (DEHP) were detected in all fresh tea leaves with DBP being the major congener of PAEs in teas followed by DiBP and DEHP. Seasonal variation, spatial distribution difference, correlationship of environmental factors, and potential health risks of PAEs were analyzed. The PAEs content in one bud and two leaves was lower than that in upper mature leaves in tea plants. The PAEs content in fresh tea leaves was the lowest in spring, while it was high in autumn and winter. The correlation analysis results showed that PAEs had significantly negative correlation with ambient air temperature, while it was positively correlated with the air quality index. PAEs analysis of spring tea in Anhui and Zhejiang provinces further indicated that the factor of provincial regions had little impact on the PAEs pollution level in tea. By contrast, the different environmental areas significantly affected PAE pollution, especially the agricultural areas. The human daily intake-based (13 g/day) risk assessment indicated that both the carcinogenic and non-carcinogenic risks (1.76 × 10 −7 -6.12 × 10 −7 ) of PAEs via tea consumption were acceptable, with the estrogen equivalence (1.60−6.29 ng E 2 /kg) being at a medium level. This study provides significant information for pollution control and risk assessment of PAEs in Chinese tea production.

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