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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 µL/mL were significantly downregulated in E. onukii. The responses to phenylacetaldehyde at concentrations of 10 and 100 µL/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. [ABSTRACT FROM AUTHOR]

The green plant bug (Apolygus lucorum Meyer-Dür) is a key pest of Bt cotton in China. Along with biological control, chemical control is one of the most important strategies in A. lucorum Integrated Pest Management (IPM). The goal of this study was to evaluate the toxicity of eight conventional insecticides to A. lucorum and to assess the susceptibility of two generalist predators Chrysopa sinica (Jieder) and Propylaea japonica (Thunbery) to insecticides that are commonly used in A. lucorum management. Via glass-vial and leaf-dip bioassay, toxicity tests with selected insecticides at two different life-stages of A. lucorum indicated significant differences between the LD50 or LC50 values for these compounds within different insecticidal classes. Phenylpyrazole fipronil had the highest toxicity to 4th-instar nymphs and adults of A. lucorum, whereas neonicotinoid imidacloprid had the lowest toxicity among the insecticides. Females were more tolerant to insecticides than were males, as shown by the higher LD50 values for females. Furthermore, laboratory tests showed that endosulfan had the highest selectivity to C. sinica and P. japonica: the selective toxicity ratios (STRs) were superior to other tested insecticides, particularly imidacloprid, and were 5.396 and 4.749-fold higher than baseline STRs, respectively. From this study, we conclude that fipronil can potentially be used to efficiently control A. lucorum. An alternative control agent worth consideration is endosulfan, owing to its relative safety to non-targeted natural enemies.

Green plant bugs Apolygus lucorum Meyer‐Dür (Hemiptera: Miridae) are among the most important piercing‐sucking insect pests of the tea plant Camellia sinensis (L.) O. Kuntze (Theaceae) and severely reduce the quality and economic benefits of tea. The preference of A. lucorum for tea plants and weed hosts, including Humulus scandens (Lour.) (Moraceae), Artemisia lavandulaefolia DC., Conyza canadensis (L.) Cronq, and Artemisia annua L. (all Asteraceae), was evaluated using an olfactometer bioassay. Volatiles from weed host plants were analyzed by electronic nose and gas chromatography/mass spectrometry. The A. lucorum adults had a significant preference for the volatiles from A. lavandulaefolia compared to volatiles from tea. Myrcene, 1,8‐cineole, and sabinene were the three dominant components in the A. lavandulaefolia flower volatiles. Artemisia lavandulaefolia was selected as a trap plant to assess the attractiveness to A. lucorum and the effects on natural enemies. The population density of A. lucorum on A. lavandulaefolia planted in tea plantations was significantly higher than that on tea. In particular, in tea fields with A. lavandulaefolia at 2 m spacing, the number of A. lucorum on trap strips of A. lavandulaefolia was higher than on tea at 10, 20, and 30 m away from the trap strips. The trap strips of A. lavandulaefolia also promoted a small increase in the presence of natural enemies in the tea agroecosystem, especially lacewings. Our research indicated that planting A. lavandulaefolia as a trap plant at 2 m spacing has the potential to manipulate the population of A. lucorum in tea plantations. [ABSTRACT FROM AUTHOR]

Tea, which is usually made from the new shoots of tea plants (Camellia sinensis), is one of the most popular and healthy beverages. The tenderness of new shoots plays a critical role in the production of high‐quality tea; however, the factors affecting the tenderness of the new shoots of tea have not been extensively studied. Here, we show that cellulose accumulation is negatively correlated with the tenderness of new shoots, including leaves and stems, by characterizing the cellulose content and visualizing cellulose in the new shoots of two cultivars ("Huangjinya" and "Yujinxiang") via toluidine blue staining. We further found that the number of cells with secondary cell walls (SCWs) and the thickness of SCWs increased with the maturity degree of stems in both cultivars. Because cellulose is the most abundant polymer in SCW, we next identified three cellulose synthase CsCesAs, CsCesA4, 7, and 8A, through homologous alignment with Arabidopsis AtCesAs. Protein sequence analysis revealed that these proteins were closely related based on the phylogenetic analysis. We finally showed that the gene expression of the three CsCesAs was positively correlated with the maturity degree and cellulose content of the new shoots. Thus, our data suggest that cellulose accumulation, especially in the SCWs, is negatively correlated with the tenderness of new shoots in tea plants. [ABSTRACT FROM AUTHOR]

BACKGROUND The red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), is an important stored‐product pest that is distributed worldwide and has developed resistance to many insecticides. Identifying novel and effective alternative insecticides is important for the control of T. castaneum. The volatile compound benzothiazole has been identified as having great acute toxic activity against T. castaneum. However, a comprehensive evaluation of a new insecticide should include both direct toxic effects and sublethal effects. The aim of this study was therefore to evaluate the effects of benzothiazole on the development and reproduction of T. castaneum. RESULTS: Exposure of fourth‐instar larvae to lethal and sublethal concentrations of benzothiazole (LC10, LC30 and LC50) significantly decreased pupation rates, food intake and growth rates in T. castaneum. Larval duration was significantly reduced by approximately 1 day in the LC30 and LC50 treatment groups. The LC50 benzothiazole caused a significant decrease in the weight of pupae and adults, fecundity and egg hatchability. Increased and decreased nutrient (carbohydrate and lipid) contents were observed in surviving larvae and pupae, respectively. The LC30 and LC50 treatments caused the down‐regulation of five growth‐positive regulated genes (PI3K, AKT, CyclinE, S6K1 and S6K2) and the up‐regulation of two growth‐negative regulated genes (4EBP and FOXO). CONCLUSION: Benzothiazole presented adverse effects on the development and reproduction of T. castaneum, further supporting benzothiazole as a highly active compound in stored‐product protection. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]