五种药剂对芒果及豆角田蓟马的防效试验

为筛鉴高效低毒的蓟马防治药剂,将20％烯啶虫胺AS等五种杀虫剂对芒果和豆角田蓟马进行了田间药效试验,通过虫口减退率和校正防效两个指标对试验进行结果分析.结果表明,20％烯啶虫胺AS对茶黄蓟马Scirtothrips dorsalis Hood和花蓟马Frankliniella intonsa Trvbom两种蓟马的防效均较为突出,其中以1 mL/L的20％烯啶虫胺AS效果最好,药后第5 d对茶黄蓟马和花蓟马的防控效果还分别维持在84.18％、77.36％,持效期较长,其次0.5％印楝素EC+N-go对两种蓟马也有较好的防效5％啶虫脒EC+N-go对茶黄蓟马的防效优于花蓟马,而20％啶虫脒*20％丁硫克百威WDG对花蓟马的防效优于茶黄蓟马各药剂对两种作物较安全.     

橘园蓟马的种类、发生规律及防治研究

本文以我国柑橘主产区当阳和赣州为试验基地,系统调查了橘园中蓟马为害的严重性及其发生规律;经鉴定发现我国柑橘主产区橘园内蓟马有11种:包括蓟马科中的茶黄蓟马Scirtothrips dorsalis Hood、褐三棕蓟马Lefroyothrips lefroyi(Bagnall)、花蓟马Frankliniella intonsa(Trybom)、八节黄蓟马Thripsflavidulus(Bagnall)、黄胸蓟马T.hawaiiensis(Morgan)、棕榈蓟马T.palmi Karny、色蓟马T.coloratus Schmutz和管蓟马科中的边腹曲管蓟马Rhaebothrips lativentris Karny、华简管蓟马Haplothrips chinensis Priesner、桔简管蓟马H.subtilissimus(Haliday)、狭翅简管蓟马H.tenuipennis Bagnall;并对蓟马进行药剂防治试验,结果表明,吡虫啉、敌百虫和阿维菌素3种药剂都能有效的减少蓟马的虫口数目,在柑橘花期之前和柑橘花期施药可以有效的降低蓟马对果实的为害率。     

外来入侵害虫——西花蓟马在山东省不同地区主要花卉上的分布

【背景】外来入侵害虫西花蓟马于2003年首次在北京郊区被发现,并逐渐扩散蔓延,目前已在我国局部地区暴发成灾。【方法】于2008～2009年通过定点调查的方法对山东省115个地区258个样点的主要花卉上的蓟马种类进行了分析。【结果】山东省主要花卉上发生的蓟马有11种,包括花蓟马、黄胸蓟马、黄蓟马、西花蓟马、棕榈蓟马、烟蓟马、禾花蓟马、横纹蓟马、腹小头蓟马、黑白纹蓟马、油加律带蓟马等,其优势种为花蓟马。外来入侵害虫西花蓟马在山东省18个地区的花卉上被发现。其中,荣成市区发生最重,占蓟马采集总量的51.86%;德州市区和青岛市区发生次之,分别占蓟马采集总量的34.21%和33.88%;其他地区西花蓟马发生量占采集总量的1.39%～18.75%。【结论与意义】西花蓟马已在山东省定殖并广泛分布,相关部门应做好西花蓟马的预防与控制工作。     

有机磷农药对韭菜虫害的防治效果及农药的微生物降解

采用3．00kg(a．i)·hm^-2辛硫磷和2．63kg(a．i)·hm^-2甲基对硫磷来防治韭菜蓟马。3d后与不施农药的对照相比,虫口减退率分别达到98．28％和98．39％;20d后虫口减退率分别达到89．94％和94．04％．用浓度分别为15．00、18．00和21．00kg(a．i)·hm^-2的辛硫磷来防治韭蛆,3d后与不施农药的对照相比,虫口减退率分别达到了80．77％、93．10％和96．98％;35d后虫口减退率分别达到了92．44％、95．0596和96．81％．施用降解菌剂对防治蓟马和韭蛆没有不良影响,但可显著降低韭菜中的农药含量．蓟马施药防治后3d喷施45．00L·hm^-2的降解菌剂,3d后与不施菌对照相比,辛硫磷和甲基对硫磷的降解率分别为99．52％和98．83％;20d后韭菜(苔)中农药含量均检测不出．韭蛆施药防治后3d灌施75．00L·hm^-2降解菌剂,35d后不同辛硫磷施用量的降解率分别为100％、100％和99．69％．     

世界上最古老的生物防治——黄柑蚁Oecophylla smaragdina Fabr. 在柑桔园中的放饲及其利用价值

本文对我国利用已有悠久历史的黄柑蚁在广东省广四县柑桔区作了调查,并对黄柑蚁消除害虫的实际情况作了观察。 在黄柑蚁数量足够的情况下,对柑桔大绿蝽象(Rhynchocoris humeralis Thunberg)有显著防治效果,对潜叶(虫斧)(Podagricomela nigricollis Chen)、粉绿象甲(Hypomeaes squamosus F.)、铜绿金龟子(Anomala cupripes Hope) 等,也有一定效果,凡有柑蚁分布均匀的树,健叶数比无蚁树多18.3％。 对介壳虫类,青翅羽衣(Lowana sp.),天牛幼虫等,完全无防治作用;与介壳虫类如吹绵介壳虫、棘粉介壳虫(Pseudococcus citriculus)及软腊介壳虫(Coccus sp.)有共生关系。 对吹绵介壳虫的天敌大红瓢虫(Rodolia rufopilosa Mulsant)、小红瓢虫(Rodolia pumilaWeise)的活动没有影响。有黄柑蚁的果园,黑蚁均被驱逐。 作者认为黄柑蚁并不是一种理想的天敌,目前在农药械供应不足及劳动力缺乏的地区,仍具有一定的利用价值。建议开展黄柑蚁过冬保护及人工饲养与放蚁的研究,以期提高和扩大利用价值。     

柑桔的两种蓝黑叶虫鉴别

柑桔恶性叶虫(Clitea metallica Chen)与柑桔花叶虫(Nodina punctatostriolata Fairm.)是柑桔的重要害虫。前一种是浙江、福建、广东柑桔区的大害虫。陈世骧(1935)报告后一种是Lamprosoma punctatostriolataFairm.的同物异名,曾在江西发现,作者于1956年在广州及惠来葵潭农场发现这害虫为害柑桔花甚烈。这两种柑桔害虫的成虫均是蓝黑色的小甲虫,外形及大小十分相似,很容易混淆,且均为害柑桔花蕾;但恶性叶虫还为害新芽、嫩茎及果实,无群居习性;而幼虫喜群居,常数十头聚集一嫩枝上,并分泌粘液及排泄粪便涂于嫩叶上,嫩叶受害焦黑而萎落,嫩枝亦枯萎。柑桔花叶虫在4、5月间出现,成虫群集为害花蕾,幼虫尚未     

香蕉园黄胸蓟马成虫种群的活动节律、消长规律与空间分布

为系统明确黄胸蓟马在香蕉园的活动节律、消长规律与空间分布。采用蓝色诱虫板诱集法和田间踏查法,在2016—2018年期间调查了香蕉园黄胸蓟马成虫的活动高度情况、日间节律、以及不同香蕉品种(南天黄、巴西蕉与皇帝蕉)与不同地区(海南澄迈、广西玉林与云南景洪)的种群消长规律,同时分析了其空间分布格局与性比。结果显示:高度与蓟马种群数量密切相关,2—6 m是香蕉园黄胸蓟马的主要活动高度范围;蓟马种群的活动节律在晴、阴与雨天基本一致,日活动高峰时段为12:00—16:00时,夜间和阴雨天均活动少;黄胸蓟马的种群动态不受香蕉作物品种和地理区域的影响,但与香蕉作物的生长期密切相关;年度消长规律呈现单峰型,香蕉进入花蕾期时,蓟马种群数量快速增长,盛花期时达到高峰,其余时期少有发生。聚集指标与Taylor回归法分析共同表明黄胸蓟马成虫在香蕉园的空间分布型为聚集式分布。性比调查发现黄胸蓟马在香蕉花蕾内的雌虫比例约为70%,表明该虫是一个雌性为主的种群。为揭示黄胸蓟马的灾变规律提供了基础数据,同时可为香蕉蓟马的适时与精准化监测预报及防治提供指导依据。     

外来人侵害虫——西花蓟马在山东省不同地区主要花卉上的分布

【背景】外来入侵害虫西花蓟马于2003年首次在北京郊区被发现,并逐渐扩散蔓延,目前已在我国局部地区暴发成灾。【方法】于2008～2009年通过定点调查的方法对山东省115个地区258个样点的主要花卉上的蓟马种类进行了分析。【结果】山东省主要花卉上发生的蓟马有11种,包括花蓟马、黄胸蓟马、黄蓟马、西花蓟马、棕榈蓟马、烟蓟马、禾花蓟马、横纹蓟马、腹小头蓟马、黑白纹蓟马、油加律带蓟马等,其优势种为花蓟马。外来入侵害虫西花蓟马在山东省18个地区的花卉上被发现。其中,荣成市区发生最重,占蓟马采集总量的51．86％;德州市区和青岛市区发生次之,分别占蓟马采集总量的34．21％和33．88％;其他地区西花蓟马发生量占采集总量的1．39％～18．75％。【结论与意义】西花蓟马已在山东省定殖并广泛分布,相关部门应做好西花蓟马的预防与控制工作。     

六种常见杀虫剂对西花蓟马和花蓟马的毒力测定

为了明确常用杀虫剂对入侵害虫西花蓟马和本地近缘优势种花蓟马的毒力作用,在室内采用菜豆浸渍饲喂法,分别测定了6种常用杀虫剂对云南昆明地区两种蓟马2龄若虫、雌虫及雄虫的毒力。结果表明:6种杀虫剂对西花蓟马和花蓟马2龄若虫和成虫的LC_(50)以6%乙基多杀菌素的最低,对西花蓟马和花蓟马2龄若虫和成虫LC_(50)值分别为:0.611、0.333 mg/L和1.731、1.202 mg/L;LC_(50)值以10%吡丙醚最高,对西花蓟马和花蓟马2龄若虫和成虫LC_(50)值分别为1238.005、845.819 mg/L和9037.110、4766.376 mg/L。6种杀虫剂对西花蓟马和花蓟马各虫态的毒力作用依次为:乙基多杀菌素阿维菌素溴氰菊酯啶虫脒吡虫啉吡丙醚,且所有供试杀虫剂对西花蓟马LC_(50)均大于花蓟马,对雌虫LC_(50)大于雄虫。说明了蓟马雌虫对杀虫剂的敏感度低于雄虫,且生物源杀虫剂的室内杀虫效果强于化学杀虫剂,是西花蓟马防治中优先选择的杀虫剂。     

蔬菜花期蓟马的种群动态与空间分布研究

西花蓟马是近年来在我国局部地区暴发成灾的重要外来入侵害虫,有关西花蓟马入侵对本地蓟马种群动态、空间分布及优势种影响的报道较少。对云南省昆明市近郊蔬菜花期的蓟马种群动态和空间分布研究表明,蔬菜上的蓟马种类主要是西花蓟马Frankliniella occidentalis(Pergande)、花蓟马F.intonsa(Trybom)、棕榈蓟马T.palmi(Karny)和端大蓟马Megalurothrips distalis(Karny);不同蔬菜上的蓟马优势种存在一定差异,其中辣椒和茼蒿上的蓟马优势种为西花蓟马;韭菜、茄子和四季豆上的蓟马优势种分别为花蓟马、棕榈蓟马和端大蓟马。各蔬菜上的蓟马种群数量以花期为多,盛花期达最大值,其中茄子花上的蓟马成虫平均虫口密度最高,为14.93头/朵。利用聚集度指标进行空间分布检测表明,不同蔬菜上蓟马成虫的空间分布型均为聚集分布,且聚集程度随密度的增加而增大。本研究可为深入探讨西花蓟马对本地蓟马的竞争取代机制积累资料,同时为西花蓟马的综合治理奠定理论基础。     

Nonhost status of Citrus sinensis cultivar valencia and C. paradisi cultivar ruby red to Mexican Anastrepha fraterculus (Diptera: Tephritidae)

Anastrepha fraterculus (Wiedemann) is recognized as a pest of citrus, apples, and blackberries in South America. In Mexico, it is mainly found in fruit of the family Myrtaceae and has never been reported infesting citrus. Here, we sought to determine whether females stemming from Mexican A. fraterculus populations (collected in the state of Veracruz) would lay eggs in 'Valencia' oranges and 'Ruby Red' grapefruit and, if so, whether larvae would hatch and develop. We worked under laboratory and seminatural conditions (i.e., gravid females released in fruit-bearing, bagged branches in a commercial citrus grove) and used Anastrepha ludens (Loew), a notorious pest of citrus, as a control species. Under laboratory conditions, A. ludens readily accepted both oranges and grapefruit as oviposition substrates, but A. fraterculus rarely oviposited in these fruit (but did so in guavas, a preferred host) and no larvae ever developed. Eggs were deposited in the toxic flavedo (A. fraterculus) and nontoxic albedo (A. ludens) regions. Field studies revealed that, as was the case in the laboratory, A. fraterculus rarely oviposited into oranges or grapefruit and that, when such was the case, either no larvae developed (oranges) or of the few (13) that developed and pupated (grapefruit), only two adults emerged that survived 1 and 3 d, respectively (5-17% of the time necessary to reach sexual maturity). In sharp contrast, grapefruit exposed to A. ludens yielded up to 937 pupae and adults survived for >6 mo. Therefore, the inability of Mexican A. fraterculus to successfully develop in citrus renders the status of Mexican A. fraterculus as a pest of citrus in Mexico as unsubstantiated.     

Biological control of Phytophthora ramorumon rhododendron

Phytophthora ramorum was found in Poland in 2000 as the causal agent of rhododendron blight. Besides eradication of diseased plants and rhododendron growing around, chemical and biological control of the pathogen is necessary. In this study in vitro activity of grapefruit extract and chitosan in the inhibition of P. ramorum growth and sporulation and their efficacy in the control of leaf and stem rot development was evaluated. Amendment of V8 juice agar and soil leachate with grapefruit extract resulted in the inhibition of colony growth and sporulation of P. ramorum. Zoosporangia were more susceptible to the extract than pathogen hyphae and chlamydospores. Chitosan only slightly inhibited the colony growth and zoosporngia production. Spraying of rhododendron inoculated with P. ramorum with grapefruit extract at conc. 165 microg/cm3 inhibited 2-3 times the spread of necrosis on stems and leaves. Pre- and postinoculation spraying of rhododendrons with chitosan at conc. of 1000 microg/cm3 suppressed the disease spread about 40%.     

Agrobacterium-mediated transient expression in citrus leaves: a rapid tool for gene expression and functional gene assay

In this study, we present a method for transient expression of the type III effector AvrGf1 from Xanthomonas citri subsp. citri strain A^w in grapefruit leaves (Citrus paradisi) via Agrobacterium tumefaciens. The coding sequence of avrGf1 was placed under the control of the constitutive CaMV 35S promoter in the binary vectors pGWB2 and pGWB5. Infiltration of grapefruit leaves with A. tumefaciens carrying these constructs triggered a hypersensitive response (HR) in grapefruit 4 days after inoculation. When transiently expressed in grapefruit leaves, two mutants, AvrGf1ΔN116 and AvrGf1ΔC83, failed to induce an HR. Moreover, using bioinformatics tools, a chloroplast transit signal was predicted at the N terminus of AvrGf1. We demonstrated chloroplast localization by using an AvrGf1::GFP fusion protein, where confocal images revealed that GFP fluorescence was accumulating in the stomatal cells that are abundant in chloroplasts. Transient expression in citrus has the potential for aiding in the development of new disease defense strategies in citrus.     

Flavonoid composition of fruit tissues of citrus species

An HPLC analysis was performed on the concentrations of flavonoids in 42 species and cultivars of the Citrus genus and those of two Fortunella and one Poncirus species according to the classification system established by Tanaka. The composition of 8 flavanones and 9 flavone/ols for these species was determined in the albedo, flavedo, segment epidermis and juice vesicle tissues, and those in the fruit and peel tissues were calculated from the composition data of the tissues. A principal component analysis showed that such neohesperidosyl flavonoids as neoeriocitrin, naringin, neohesperidin, and rhoifolin had large factor loading values in the first principal component for each tissue. The flavonoid composition of citrus fruits was approximately the same within each section of Tanaka's system, except for the species in the Aurantium section and those with a peculiar flavonoid composition such as Bergamot (C. bergamia), Marsh grapefruit (C. paradisi), Sour orange (C. aurantium), and Shunkokan (C. shunkokan). The Aurantium section included both naringin-rich and hesperidin-rich species.     

Estimate of Yield Loss from the Citrus Nematode in Texas Grapefruit

Chemical control of the citrus nematode, Tylenchulus semipenetrans Cobb, has consistently increased yield of grapefruit on sour orange rootstock in Texas. In this study, data from chemical control tests conducted from 1973 to 1980 were analyzed to determine the relationship between nematode counts and grapefruit yield and fruit size. The correlation between yield and nematode counts was negative (r = -0.47) and highly significant (P < 0.01). The data best fit the exponential decay curve: y = 160.3e^-0.0000429 where y = yield in kg/tree and x = nematodes/100 cm³ of soil. The correlation between fruit size and nematode counts was not significant because yield and fruit size were inversely related. Yield loss in an average untreated orchard was estimated to be 12.4 tons/ha. Economic loss to citrus nematode in Texas grapefruit, assuming no treatment and an average on-tree price of $60/ton, was estimated to be $13.2 million annually.     

Effect of artemether alone and in combination with grapefruit juice on hepatic drug-metabolising enzymes and biochemical aspects in experimental Schistosoma mansoni

Artemether is an efficacious antimalarial drug that also displays antischistosomal properties. Grapefruit juice increases the oral availability of a variety of the CYP3A4 substrates. This study was designed to evaluate the effect of repeated administration of grapefruit juice with artemether on the hepatic activities of cytochrome P-450 (CYP450) and cytochrome b5 (cyt b5), on the serum levels of some biochemical enzymes and antischistosome efficacy. Results showed that administration of grapefruit juice alone induced more inhibition in the hepatic activities of CYP450 and cyt b5 than that produced by Schistosoma mansoni infection. Moreover, it enhanced degeneration of eggs and accelerated healing of the pathological granulomatous lesions. Treatment of S. mansoni-infected mice with artemether at a total dose of 300 mg/kg resulted in total and female worm burden reductions of 66.7 and 90.1%, respectively, hence protecting the host from damage induced by schistosome eggs. Treatment of S. mansoni-infected mice with artemether at 150 mg/kg reduced the total and female worm numbers by 43.3 and 54.4%, respectively, thus somewhat ameliorating hepatic granulomatous lesions compared with the infected untreated group. This was associated with no change in the hepatic activities of CYP450 and cyt b5 and in the serum levels of total protein, albumin, globulin and alanine aminotransferase compared with the uninfected control group. Coadministration of grapefruit juice with the lower dose (150 mg/kg) of artemether eliminated eggs and granulomatous reactions. In this group, the inhibitory effects of grapefruit juice on CYP450 and cyt b5 were apparent but serum liver enzymes were unchanged compared with the uninfected control group. Coadministration of grapefruit juice with artemether achieved complete protection of the host from damage induced by schistosomal infection.     

Molecular characterization of XopAG effector AvrGf2 from Xanthomonas fuscans ssp. aurantifolii in grapefruit

Xanthomonas fuscans ssp. aurantifolii group C strains exhibit host specificity on different citrus species. The strains possess a type III effector, AvrGf2, belonging to the XopAG effector gene family, which restricts host range on citrus. We dissected the modular nature and mode of action of AvrGf2 in grapefruit resistance. XopAG effectors possess characteristic features, such as a chloroplast localization signal, a cyclophilin‐binding domain characteristic amino acid sequence motif (GPLL) and a C‐terminal domain‐containing CLNAxYD. Mutation of GPLL to AASL in AvrGf2 abolished the elicitation of the hypersensitive response (HR), whereas mutation of only the first amino acid to SPLL delayed the HR in grapefruit. Yeast two‐hybrid experiments showed strong interaction of AvrGf2 with grapefruit cyclophilin (GfCyp), whereas AvrGf2‐SPLL and AvrGf2‐AASL mutants showed weak and no interaction, respectively. Molecular modelling and in silico docking studies for the cyclophilin–AvrGf2 interaction predicted the binding of citrus cyclophilins (CsCyp, GfCyp) to hexameric peptides spanning the cyclophilin‐binding domain of AvrGf2 and AvrGf2 mutants (VAGPLL, VASPLL and VAAASL) with affinities equivalent to or better than a positive control peptide (YSPSA) previously demonstrated to bind CsCyp. In addition, the C‐terminal domain of XopAG family effectors contains a highly conserved motif, CLNAxYD, which was identified to be crucial for the induction of HR based on site‐directed mutagenesis (CLNAxYD to CASAxYD). Our results suggest a model in which grapefruit cyclophilin promotes a conformational change in AvrGf2, thereby triggering the resistance response.     

Amounts and variation in grapefruit juice of the main components causing grapefruit–drug interaction

A method for the determination of three furocoumarins containing two new chemicals (GF-I-1 and GF-I-4) in commercially available grapefruit juice and grapefruit itself was developed using high-performance liquid chromatography (HPLC). These components isolated from grapefruit juice have 5-geranyloxyfurocoumarin dimer structures showing extremely high affinities for a form of cytochrome P450 (CYP3A4). Considerable differences were observed on the contents among commercial brands and also batches. The contents were determined to be 321.4±95.2 ng/ml GF-I-1, 5641.2±1538.1 ng/ml GF-I-2 and 296.3±84.9 ng/ml GF-I-4 in twenty-eight white grapefruit juices. These chemicals were not detected in beverages from orange, apple, grape and tangerine, except that trace amount of GF-I-2 and GF-I-4 were found in lemon juice. The average levels of these furocoumarins were lower in the juice from red grapefruit than a white one. The highest level of these components were found in the fruit meat.     

Preparation of Acetylated Grapefruit Peel Polysaccharide

Grapefruit peel polysaccharide has antioxidant, antitumor, hypoglycemic and other biological activities, and chemical modification can further improve the properties of the polysaccharide. Acetylation modification of polysaccharides has the advantages of simple operation, low cost and little pollution, and is widely used at present. Different degrees of acetylation modification have different effects on the properties of polysaccharides, so it is necessary to optimize the preparation technology of acetylated grapefruit peel polysaccharides. In this article, acetylated grapefruit peel polysaccharide was prepared by acetic anhydride method. With the degree of acetyl substitution as the evaluation index, combined with the analysis of sugar content and protein content in the polysaccharide before and after modification, the effects of three feeding ratios of 1:0.6, 1 : 1.2 and 1 : 1.8 (polysaccharide: acetic anhydride, mass/volume) on acetylation modification were explored through single factor experiments. The results showed that the optimum ratio of material to liquid for acetylation modification of grapefruit peel polysaccharide was 1:0.6. Under these conditions, the degree of substitution of acetylated grapefruit peel polysaccharide was 0.323, the sugar content was 59.50 % and the protein content was 1.038 %. The results provide some reference for the study of acetylated grapefruit peel polysaccharide.     

Evidence for host plant preference by Iphiseiodes quadripilis (Acari: Phytoseiidae) on Citrus

In this study, we present field and laboratory evidence on the preference of Iphiseiodes quadripilis (Banks) for grapefruit (Citrus paradisi Macfadyen) leaves compared with sweet orange (Citrus sinensis (L.) Osbeck) leaves. This preference was confirmed in four orchards whether leaf samples were taken from either border trees of contiguous grapefruit or sweet orange or interior row trees with both citrus species in adjacent rows. Iphiseiodes quadripilis was most abundant in grapefruit trees in spite of the greater abundance of the Texas citrus mite, Eutetranychus banksi (McGregor) (Acari: Tetranychidae) in sweet orange trees. Similar preference responses were observed in laboratory tests using a Y-tube olfactometer whether I. quadripilis were collected from sweet orange or grapefruit. Iphiseiodes quadripilis collected from grapefruit trees showed significant preference for grapefruit over sweet orange leaves in contact choice tests using an arena of alternating leaf strips (12 mm long × 2 mm wide) of sweet orange and grapefruit. However, I.␣quadripilis collected from sweet orange trees did not show preference for either grapefruit or sweet orange leaves. Based on these results, grapefruit leaves foster some unknown factor or factors that retain I. quadripilis in greater numbers compared with sweet orange leaves.