Probing behavior of the tea green leafhopper on different tea plant cultivars

The probing behaviors of the tea green leafhopper, Empoasca vitis (Gothe), on 9 tea cultivars were studied using video-text Direct Current-Electrical Penetration Graph, i.e., DC-EPG. The following 7 types of waveforms produced by the leafhopper stylet probing were determined: A, stylet pathway formation; S, salivation when stylets pierce into and stay in phloems; C, active ingestion before stylets reach phloems; E and F, passive ingestion in phloems; R, the insect resting with its stylet inserted into the leaf tissue and NP without probing. The 9 tested tea cultivars were categorized into 3 groups by the cluster analysis according to the number of probes per insect, waveform durations, or duration per probe of various waveforms on different tea cultivars. Waveforms S, E and F correlated to the main feeding activity of the leafhopper and may provide valuable information on predicting the resis-tance level of the tea plants to the leafhopper. The resistance level of the 9 tea cultivars to the leafhopper was ranked based on the durations of waveforms S, E and F, as well as the duration per probe including various waveforms. The ranking order of the resis-tance was: Longjingchangye > Hangdan > Zhenghedabaicha > Qianmei 601 > Hongyafoshuo > Zhongcha 102 > Zhongcha 302 > Longjing 43 > Anjibaicha, which corresponded to the resistance level determined by the population density (infestation) of the leaf-hopper on the 9 tea cultivars in the tea fields. Our study suggests that this simple and convenient DC-EPG technique might have great potential as a reliable tool to predict the resistance of tea cultivars to the tea leafhopper.     

假眼小绿叶蝉（Empoasca vitis Gothe）在不同品种茶树上的取食行为

应用可视DC-EPG方法研究了假眼小绿叶蝉(Empoasca vitis Gothe)在9个品种茶苗上的口针刺探行为,共发现并初步确定了7种主要波型,即A波、S波、C波、E波、F波和R波、以及非刺探波NP波。A波为刺探波,S波为口针向韧皮部刺探和进入韧皮部中的分泌唾液波,C波为口针到达韧皮部之前的主动取食波,E波和F波为口针在韧皮部中吸收波,R波为取食间歇波。以该叶蝉在不同品种茶树上的平均刺探次数和各波形平均持续时间为指标,或者以其在不同品种茶树上含有各波形的单次刺探平均持续时间为指标,分别进行聚类分析,均将9个品种分为3个不同的组。S、E和F波对应着假眼小绿叶蝉在茶树上的主要取食活动,可能与茶树抗假眼小绿叶蝉的取食密切相关。以S、E和F各波的平均持续时间、以及含有各波形的单次刺探的平均持续时间为指标,对品种的抗性强弱排序,评判9个茶树品种抗叶蝉取食能力由强至弱的顺序为:龙井长叶、黄旦、政和大白茶、黔湄601、红芽佛手、中茶102、中茶302、龙井43和安吉白茶。该顺序与田间查得的9个品种茶树上假眼小绿叶蝉种群密度由小到大的顺序一致,表明DC-EPG方法简捷、可信度高,可作为检测茶树品种对叶蝉抗性的有效手段之一。     

显著调控假眼小绿叶蝉行为的迷迭香挥发物鉴定

茶园生态系中生长着众多草本和木本植物,迷迭香就是其中常见的木本杂草。以其幼嫩部分为味源、茶园重要害虫假眼小绿叶蝉为试虫,用Y形管嗅觉仪做行为测定,以洁净空气为CK,发现随着味源剂量增加,其引诱的假眼小绿叶蝉数增至一个数值再减少,二者呈抛物线关系。从迷迭香挥发物中鉴定出46种化合物,包含醇类9种、酮类4种、酯类4种、酸类1种、烯烃类18种、烷烃类7种、醚类1种、醛类1种和酚类1种。醇类含量最大,占总量52.20%;单组分中桉树脑、左旋α-蒎烯和马鞭草烯酮的含量最大,分别占总量的42.54%、10.37%和6.82%。使用迷迭香挥发物中含量较大的25种组分为味源,每味源配制几种剂量,以正己烷为CK,用Y形管嗅觉仪进行行为测定,发现10-2g/mL樟脑、10-4g/mL石竹烯、10-6g/mL和10-8g/mLα-水芹烯、10-4g/mL和10-10g/mLα-松油醇、10-10g/mL和10-8g/mL桉树脑显著引诱假眼小绿叶蝉;而10-10g/mLβ-蒎烯显著排斥假眼小绿叶蝉。经分析认为:茶园中除了茶树之外,还有其它植物挥发物引诱假眼小绿叶蝉,可为筛选茶园中诱虫植物提供参考。     

Behavioral responses for evaluating the attractiveness of specific tea shoot volatiles to the tea green leafhopper,Empoaca vitis

Abstract The tea green leafhopper, Empoasca vitis Göthe, 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.     

基于EPG技术分析茶树品种对茶小绿叶蝉的抗性及其相关的抗性物质

为深入探讨假眼小绿叶蝉在茶树上的刺探行为,进而筛选合适的刺探电位(electrical penetration graph,EPG)参数作为评判茶树抗感性指标,遂比较紫鹃、宁波黄金芽和黄观音等11个国家级和特色茶树良种对该叶蝉抗感性,并解析茶树抗感性与主要化学成分的相关性。使用刺探电位仪检测了该叶蝉在这11个茶树品种上的多种刺探行为及其参数、以聚类分析等方法解析各品种上EPG参数而判断每品种对于叶蝉的抗感性;再以HPLC检测茶叶主要成分,分析抗感性与化学成分的关联程度。结果如下:(1)进一步明确了代表该叶蝉在茶树上取食行为的7种EPG波形及其可能的生物学意义,即Np、A、S、C、E、F和R波,解析了各种波形的特征和出现规则,认为E波、F波以及未确定生物学意义的R波是抗性相关波。(2)在5h测试期间,叶蝉在黄观音和龙井43品种上的刺探次数最多,紫鹃、宁波黄金芽和金观音上的次之,铁观音和安吉白茶上的最少;E波平均持续时间在铁观音和黄牡丹上最长,乌牛早和安吉白茶上次之,紫鹃上最短;F波平均持续时间在黄观音上最长,紫鹃、龙井43和宁波黄金芽上次之,金观音上最短。(3)以刺探次数、韧皮部取食波E波历期、韧皮部取食困难波F波历期为指标,将11个品种聚为2类,即第Ⅰ类:安吉白茶、乌牛早、紫牡丹、中茶108、黄牡丹和铁观音;第Ⅱ类为黄观音、龙井43、紫鹃、宁波黄金芽和金观音;抗性强弱为:第Ⅱ类第Ⅰ类。(4)从感性至抗性品种,儿茶素类含量明显升高,且儿茶素总量与E波历期显著负相关(P为深入探讨假眼小绿叶蝉在茶树上的刺探行为,进而筛选合适的刺探电位（electrical penetration graph,EPG）参数作为评判茶树抗感性指标,遂比较紫鹃、宁波黄金芽和黄观音等11个国家级和特色茶树良种对该叶蝉抗感性,并解析茶树抗感性与主要化学成分的相关性。使用刺探电位仪检测了该叶蝉在这11个茶树品种上的多种刺探行为及其参数、以聚类分析等方法解析各品种上EPG参数而判断每品种对于叶蝉的抗感性;再以HPLC检测茶叶主要成分,分析抗感性与化学成分的关联程度。结果如下：（1）进一步明确了代表该叶蝉在茶树上取食行为的7种EPG波形及其可能的生物学意义,即Np、A、S、C、E、F和R波,解析了各种波形的特征和出现规则,认为E波、F波以及未确定生物学意义的R波是抗性相关波。（2）在5h测试期间,叶蝉在黄观音和龙井43品种上的刺探次数最多,紫鹃、宁波黄金芽和金观音上的次之,铁观音和安吉白茶上的最少;E波平均持续时间在铁观音和黄牡丹上最长,乌牛早和安吉白茶上次之,紫鹃上最短;F波平均持续时间在黄观音上最长,紫鹃、龙井43和宁波黄金芽上次之,金观音上最短。（3）以刺探次数、韧皮部取食波E波历期、韧皮部取食困难波F波历期为指标,将11个品种聚为2类,即第Ⅰ类：安吉白茶、乌牛早、紫牡丹、中茶108、黄牡丹和铁观音;第Ⅱ类为黄观音、龙井43、紫鹃、宁波黄金芽和金观音;抗性强弱为：第Ⅱ类 > 第Ⅰ类。（4）从感性至抗性品种,儿茶素类含量明显升高,且儿茶素总量与E波历期显著负相关（P < 0.05）;咖啡碱、氨基酸和可溶性糖含量皆未与E波、F波历期明显相关。认为：E波和F波历期以及刺探次数可作为茶树抗感性的主要参数;R波可能与韧皮部取食抗性相关;儿茶素类是抗性相关物质。研究可为深入探讨茶树抗虫机理提供参考。     

茶园间作柑桔杨梅或吊瓜对叶蝉及蜘蛛类群数量和空间格局的影响

为评价茶园间作几种常见经济作物对重要害虫假眼小绿叶蝉及其主要天敌蜘蛛类群数量和空间格局的影响,遂选乌牛早品种纯茶园、乌牛早分别与柑桔、杨梅和吊瓜的间作茶园、以及安吉白茶与吊瓜间作茶园,2007年9月上旬—2008年12月下旬,每旬1次调查茶丛上、中、下层叶蝉和各种蜘蛛的数量。结果表明:(1)与纯茶园相比,间作茶园叶蝉种群数量和蜘蛛类群个体数量显著地增加,间作茶园蜘蛛种数显著地增加;(2)间作茶园茶丛上、中、下层叶蝉、蜘蛛个体数量分布明显区别于纯茶园茶丛上、中、下层叶蝉、蜘蛛个体数量分布;(3)茶丛上层的嫩梢是制作高档茶的原料,而纯茶园茶丛上层叶蝉虫口百分率为54.16%,间作茶园茶丛上层叶蝉虫口百分率皆减小,并且叶蝉高峰期间蜘蛛的跟随效应增强;(4)间作增加了经济收入并减少了防治次数。认为:(1)间作可在一定程度上调控叶蝉种群、蜘蛛类群的数量和空间格局;(2)间作可减轻叶蝉为害造成的产值损失,增强了茶园群落对于叶蝉的自然控制潜能。     

迷迭香挥发物不同组合对假眼小绿叶蝉行为的调控

为探讨茶园群落中非茶植物气味引诱或驱避重要茶树害虫假眼小绿叶蝉的效应,遂将茶园常见杂草迷迭香挥发物中樟脑、α-松油醇和石竹烯分别配成10-2g/m L剂量,再等量组成混合物,在每个橡皮头上载100#L制成诱芯,附于素馨黄粘板上,于茶园中诱捕假眼小绿叶蝉,发现这种三组分诱芯明显地驱避假眼小绿叶蝉。将行为反应中分别对假眼小绿叶蝉呈现显著引诱效应的10-2g/m L樟脑、10-4g/m L石竹烯、10-6g/m Lα-水芹烯、10-4g/m Lα-松油醇和10-8g/m L桉树脑等量配成五组分混合物,同法制成诱芯,附于素馨黄粘板,诱捕假眼小绿叶蝉。发现五组分诱芯:(1)显著引诱假眼小绿叶蝉,诱效稍强于现价段茶园中使用的源于茶梢挥发物的诱芯;(2)每日诱捕的假眼小绿叶蝉数与天数呈抛物线关系;(3)加入液体石蜡作为缓释剂,可将诱效的半衰期延长2.5—4.0d;(4)18:00—6:00诱得的假眼小绿叶蝉数量占全天的70%—75%。分析认为:非茶植物迷迭香的挥发物中含有显著引诱假眼小绿叶蝉信息物质,这类信息物质制成的五组分诱芯的诱效较强,可以作为一种防治假眼小绿叶蝉的手段,早晨和黄昏是最佳诱捕时分。     

Extraction behavior of caffeine and EGCG from green and black tea

A dipping method was developed to extract the catechins (EGCG) and alkaloids (caffeine) from green tea (Korea) and black tea (Sri Lanka). The effects of the solvent composition (water vs. ethanol), extraction time, temperatures, and solvent pH on the amount of catechins (EGCG) and alkaloids (caffeine) extracted from green and black tea were investigated. Reversedphase high-performance liquid chromatography (RP-HPLC) was used to analyze the catechins (EGCG) and alkaloids (caffeine) extracted. The content of EGCG and caffeine in green tea extracts was in the range of 2.04∼0.30 and 10.22∼0.85 mg/g, respectively. The amount of EGCG and caffeine in black tea extracts was in the range of 0.32∼0.24 and 5.26∼1.01 mg/g, respectively. The amount of caffeine extracted from green and black tea was greater than the amount of EGCG. Pure water is the best solvent for extracting EGCG and caffeine from green tea. The amount of caffeine extracted from green and black tea increased as the temperature, extraction time, and hydrogen ion concentration of the solvent increased. Although the amount of EGCG extracted from green tea increased as the temperature increased, the amount of EGCG extracted from black tea was not affected by temperature. The extraction of EGCG from both green and black tea was not affected by the hydrogen ion concentration of the solvent.     

矿物油对茶园小贯小绿叶蝉的控制效果和对茶叶感官品质的影响

小贯小绿叶蝉Empoasca(Matsumurasca)onukii Matsuda是东亚茶树的重要害虫之一,目前在我国主要采用化学防治。本文研究一种nC23园艺用矿物油、加德士的D-C-Tron NR对其产卵和取食行为的影响,以及对其田间种群的控制效果,为在茶园使用矿物油替代化学农药进行防治提供依据。室内选择性试验结果表明,用矿物油150倍液、200倍液处理茶树离体嫩梢对小贯小绿叶蝉成虫都有显著的拒食和产卵忌避效果,第3天的拒食率分别为85.59%、89.17%,产卵忌避率分别为70.22%、91.5%,200倍液处理对若虫也有显著的驱避和拒食效果,第2天驱避率为81.96%,第3天拒食率为85.86%。田间试验结果表明,矿物油100倍液、200倍液、300倍液处理都显著降低小贯小绿叶蝉田间种群的虫口密度,其中100倍液和200倍液的防治效果无显著差异,处理后5 d若虫的校正减退率分别达89.13%、87.63%,成虫分别达87.58%、84.22%,都显著高于300倍液的防效。田间试验结果还表明,矿物油3个浓度处理后茶梢上的卵量显著减少,其中100倍液处理第7天的产卵忌避率最高,达80.86%,而各处理茶园蜘蛛的数量与对照相比都没有显著差异。另外,用矿物油200倍液喷施茶树后5 d、10 d采摘的茶芽制成绿茶,经感官评审与对照没有差异,说明矿物油对小贯小绿叶蝉具有较好的防治效果,而且对茶园蜘蛛安全,对茶叶感官品质没有影响,可以在小绿叶蝉防治中推广应用。     

Aberrations caused by neem oil odour in green leafhopper feeding on rice plants

Using an electronic device and a lignin-specific dye, the feeding behaviour of the green leafhopper,Nephotettix virescens (Distant), (Homoptera: Cicadellidae) was monitored on rice plants kept in an arena permeated with the odour of neem (Azadirachta indica A. Juss) seed oil. The garlicky odour of neem oil disrupted the normal feeding behaviour of the leafhopper. Phloem feeding byN. virescens on rice plants kept in an arena permeated with odour of 6, 12, or 25% neem oil was significantly reduced compared with that on control plants kept in an arena with paraffin oil or 1.66% aqueous Teepol solution. Reduced intake from phloem was associated with a significant increase in the insect's probing frequency and an increase in durations of salivation and xylem ingestion.

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Alterations du comportement sur riz de Nephotettix virescens, dues à l'odeur d'essence de neem (Azadirachta indica)

Résumé De nombreux essais en plein champ à l'I.R.R.I. ont révélé une réduction du T.V. (tungro virus) transmis par (Nephotettix virescens) sur des parcelles de riz sensible non-traitées, entourées de parcelles pulvérisées périodiquement avec de l'essence de graines de neem (Azadirachta indica).L'essence de neem a une forte odeur d'ail, perceptible à distance. Nous avons examiné l'effet de l'odeur d'essence de neem sur le comportement alimentaire deN. verescens, grâce à un dispositif électronique et un colorant spécifique de la lignine. Sur du riz maintenu dans une enceinte imprégnée d'odeur d'essence de neem, nous avons constaté une diminution de la consommation de phloème, une augmentation significative de la fréquence des piqûres et une augmentation de temps de salivation et d'absorption de xylème. Ces altérations du comportement alimentaire provoquées par l'odeur d'essence de neem peuvent expliquer la diminution de la fréquence du T.V. spécifique du phloème dans des champs de riz non-traités, entourés de champs pulvérisés avec de l'essence de neem.

     

Antimicrobial effects of copper nanoparticles with green tea and neem formulation

Nanotechnology is the science which is about manipulating matter, atom by atom and is associated with particles smaller than 100 nm in size. Copper nanoparticles are used mainly due to its surplus amount, low cost, easy availability and biocompatible property. Green synthesis of copper nanoparticles is very simple, economical and eco-friendly method that does not involve any toxic chemicals. The aim of our study is green synthesis of copper nanoparticles using green tea and neem formulation and assessment of its antimicrobial effects. 20mM of copper sulphate solution is mixed with 40mL of plant extract and 60 mL of distilled water was added and made it into 100 ml solution. Once the copper nanoparticles are synthesized the solution is characterized using UV- vis-spectroscopy and was scanned in double beam UV-vis- spectrophotometer from 300 nm to 700nm wavelength. The antimicrobial property of copper nanoparticle is evaluated by agar well diffusion method. The colour change from green to brown and peak observed in UV-vis- spectrophotometer was associated with the synthesis of copper nanoparticles. Copper nanoparticle from green tea and tea extract has good antimicrobial activity against S.mutans, C.albicans, E.faecalis, & S.aureus. Copper nanoparticles can be efficiently synthesised from green and neem formulation. These copper nanoparticles showed good antibacterial properties and are effective against oral pathogens.     

Analysis of tea plant resistance to tea green leafhopper,Empoasca onukii,by detecting stylet‐probing behavior with DC electropenetrography

The tea green leafhopper, Empoasca onukiiMatsuda (Hemiptera: Cicadellidae: Typhlocybinae), is a serious pest of tea plants in East Asia. Previous work has shown that two tea germplasms, Cd19 and Cd289, sustain less hopperburn damage by E. onukii than does Camellia sinensis (L.) O. Kuntze cv. ‘Yabukita’ (Theaceae), and E. onukii excretes less honeydew on these germplasms than on the susceptible Yabukita. This study investigated the feeding behavior of E. onukii with a direct current electropenetrograph (DC EPG) to compare feeding behaviors, including ingestion, on resistant tea germplasms and Yabukita. Feeding behaviors on the resistant germplasms were significantly restricted, with few bouts of active ingestion of short duration and long periods of non‐probing, whereas E. onukii engaged in active ingestion of long duration many times on the susceptible cv. Yabukita. The tea germplasms, Cd19 and Cd289, therefore showed strong resistance to E. onukii. Furthermore, the shape of puncture holes left after probing was compared between the susceptible Yabukita and the resistant germplasms. The puncture holes on Cd19 and Cd289 were indistinct in shape and closed compared with those on Yabukita.     

Detection of pest species with different ratios in tea plant based on electronic nose

It is highly possible that tea (Camellia sinensis) plant is attacked by more than one pest species at the same time, and the determination of their proportion is of great significance to the management of tea plants. However, there are no literatures focusing on it previously. In this work, two pest species (Ectropis obliqua and Ectropis grisescens) in six different ratios (10:0, 8:2, 6:4, 4:6, 2:8 and 0:10) were applied to attack tea plants and electronic nose (E‐nose) was employed to detect them, labelled as group 10:0, 8:2, 6:4, 4:6, 2:8 and 0:10, respectively. Two prediction methods were applied to predict the ratio of E. obliqua and E. grisescens attacking tea plant and their performances were compared. The first method employed regression algorithm for prediction analysis based on the whole E‐nose data directly. The second method classified tea plants into three main classes (the first class contained group 10:0, the second class contained groups 8:2, 6:4, 4:6 and 2:8, and the third class contained group 0:10) first, then regression algorithm was applied to deal with the second class for prediction analysis. The results showed that the second method had a better performance. Its discrimination results showed 100% of the correct classification rate for training set and 93.75% for testing set. Meanwhile, its prediction results showed 0.0005 of root mean square error (RMSE) for calibration set, 0.0064 for validation set and 99.07% of fitting correlation coefficients (R²) for calibration set, 91.22% for validation set, which were acceptable for prediction analysis and proved that E‐nose was a feasible technique for pests' ratio prediction.     

茶假眼小绿叶蝉对不同茶香精和寄主植物的趋性反应

利用"T"形室观察了茶假眼小绿叶蝉Empoasca vitis Gthe对4种茶香精和3种寄主植物的趋性反应。结果表明,假眼小绿叶蝉对不同茶香精粉和寄主植物的趋性反应不同。叶蝉对绿茶和乌龙茶A香精有明显的趋向反应,而对乌龙茶B香精即铁观音茶香精则有明显的忌避反应,对红茶香精则无反应。假眼小绿叶蝉对茶梢和青菜的趋性反应无显著差异,而对茶梢和大豆的趋性反应有差异,表现出更喜好趋向茶梢。     

茶园间作不同绿肥对节肢动物群落结构和多样性的影响

【目的】研究在茶园中合理间作绿肥对茶园节肢动物群落结构和多样性的影响。【方法】本文在茶园中分别设间作铺地木兰+罗顿豆、圆叶决明+白三叶、白三叶+平托花生3种不同绿肥组合处理,并设不间作绿肥、常规除草的茶园为对照。【结果】间作不同绿肥均能提高茶园节肢动物群落的物种丰富度和群落多样性,提高茶园捕食性天敌昆虫、蜘蛛和寄生性天敌在茶园冠层群落的比率;不同处理茶园冠层节肢动物Shannon-wiener多样性指数(H)、Simpson指数(D)和均匀度指数变化趋势基本一致;茶冠层的节肢动物群落多样性指数在4类不同处理茶园间差异显著;间作绿肥增加了茶园的生物多样性,4类不同处理茶园茶冠层群落相似性系数在0.741~0.892之间,表明4类不同处理茶园冠层群落在物种组成上有较高的相似性。4类不同处理茶园害虫与天敌两类群功能团的丰盛度之间成显著的正相关,表明天敌对害虫的空间数量跟随效应强,主要表现为二者数量间的相互作用。灰色关联度分析表明在4类不同处理茶园中的群落节肢动物物种数/个体数、天敌物种数/害虫物种数、害虫丰富度与多样性指数和均匀度指数的关联系数较高,反应了群落的多样性和稳定性。【结论】间作增强了茶园群落的生物多样性,提高害虫天敌的种类和个体数,有利有效发挥天敌对有害生物的生态控制。     

Attractiveness of host volatiles combined with background visual cues to the tea leafhopper,Empoasca vitis

The tea green leafhopper, Empoasca vitis (Göthe) (Hemiptera: Cicadellidae), is a serious pest of tea plants. We examined the behavioral responses of E. vitis adults to odors from the shoots of three host plants in a Y‐tube olfactometer with background visual cues. The host plants were tea [Camellia sinensis (L.) Kuntze (Theaceae)], peach [Prunus persica (L.) Siebold & Zucc. (Rosaceae)], and grapevine [Vitis vinifera L. (Vitaceae)]. Volatiles from the shoots were analyzed. Both yellow‐green and gold backgrounds enhanced the olfactory responses of E. vitis adults to tea plant odors, and this enhancement was stronger under a high light intensity. On the yellow‐green background, E. vitis adults significantly preferred the odors from shoots of the three host plants compared with clean air. Moreover, E. vitis adults preferred grapevine odor over the tea plant odor. The volatile blends of the three plant species were distinctly different. Peach plant shoots emitted the greatest amount of volatiles, whereas grapevine shoots released the greatest diversity of compounds. These results provide evidence that background visual cues could enhance the response of E. vitis adults to host‐plant volatiles. The leafhoppers can discern different host odors, suggesting the possibility of using peach plant and grapevine odors to monitor and manage this pest in tea plantations.     

Microwave‐assisted water extraction of green tea polyphenols

Introduction – Green tea, a popular drink with beneficial health properties, is a rich source of specific flavanols (polyphenols). There is a special interest in the water extraction of green tea polyphenols since the composition of the corresponding extracts is expected to reflect the one of green tea infusions consumed worldwide. Objective – To develop a microwave‐assisted water extraction (MWE) of green tea polyphenols. Methodology – MWE of green tea polyphenols has been investigated as an alternative to water extraction under conventional heating (CWE). The experimental conditions were selected after consideration of both temperature and extraction time. The efficiency and selectivity of the process were determined in terms of extraction time, total phenolic content, chemical composition (HPLC‐MS analysis) and antioxidant activity of the extracts. Results – By MWE (80°C, 30 min), the flavanol content of the extract reached 97.46 (± 0.08) mg of catechin equivalent/g of green tea extract, vs. only 83.06 (± 0.08) by CWE (80°C, 45 min). In particular, the concentration of the most bioactive flavanol EGCG was 77.14 (± 0.26) mg of catechin equivalent/g of green tea extract obtained by MWE, vs 64.18 (± 0.26) mg/g by CWE. Conclusion – MWE appears more efficient than CWE at both 80 and 100°C, particularly for the extraction of flavanols and hydroxycinnamic acids. Although MWE at 100°C typically affords higher yields in total phenols, MWE at 80°C appears more convenient for the extraction of the green tea‐specific and chemically sensitive flavanols. Copyright © 2009 John Wiley & Sons, Ltd.