叶绿素荧光成像技术监测苗期小麦白粉病初探

为探究叶绿素荧光成像技术在小麦白粉病监测应用中的可行性, 本研究对接种6个不同浓度小麦白粉菌分生孢子的小麦幼苗离体叶段?一叶一心期幼苗和二叶一心期幼苗以及接种后不同时期进行叶绿素荧光成像测定, 并对导出的叶绿素荧光参数与病情严重度的关系进行分析?结果发现, 接种不同浓度白粉菌分生孢子的小麦离体叶段或幼苗的Fv/Fm图像可以在一定程度上反映出小麦白粉病菌的侵染程度?接种小麦白粉菌后第3天, Fv/Fm值随接种浓度的变化规律不明显, 但从接种后第5天开始, Fv/Fm值随接种浓度的增加而下降, 且未接种的小麦幼苗或离体叶段的Fv/Fm值显著高于接种处理, 接种浓度最高(5 mg/mL)的处理其Fv/Fm值显著低于同时期其他接菌处理?小麦白粉病严重度与叶绿素荧光参数之间的相关性分析表明, Fv/Fm和Chlidx与病害严重度均极显著负相关, 在此基础上, 分别建立了小麦离体叶段?一叶一心幼苗及二叶一心幼苗的基于参数Fv/Fm或Chlidx的病害严重度估计模型?对模型的拟合效果进行比较发现, 基于Fv/Fm或Chlidx的病害估计模型其RMSE或R2比较接近, 因此叶绿素荧光参数Fv/Fm或Chlidx用来估计苗期小麦白粉病发生程度是可行的?本研究为叶绿素荧光成像技术在小麦白粉病监测预警中的应用奠定了理论基础, 具有一定的应用前景?     

豌豆离体叶片鉴定白粉病抗性方法

1997～2001年对豌豆离体叶片鉴定白粉病抗性方法进行了研究。结果表明,将豌豆苗期离体叶片在垫有两层湿滤纸的培养皿内培养,并人工接种白粉病菌,能鉴定出豌豆品种抗白粉病的差异。鉴定结果与田间成株期的抗病性表现基本一致。温度、光照强度、叶龄、病菌接种量等因素影响离体叶片白粉病发生速度或保绿时间。离体鉴定较适宜在温度18～20℃、光照强度3600lx以上、每天12h光照与12h黑暗交替的条件下进行。最适叶龄为二叶一心期或三叶一心期的初展叶。较适宜的接种量为每1cm~2叶面积接种5.5×10~3个分生孢子。     

不同硅源制剂对小麦白粉病的作用效果及对白粉病菌孢子萌发的影响

 研究了不同形态硅源制剂二氧化硅纳米粒子溶胶(60nm和100nm)、正硅酸乙酯、硅酸钠对小麦白粉病的作用效果以及对白粉病菌孢子萌发的影响。结果表明,在相同浓度下几种硅源制剂处理盆栽小麦幼苗对白粉病防效分别为48.78%、43.73%、40.31%和33.29%,室内处理小麦离体叶段对白粉病抑制率分别为59.67%、53.51%、51.10%和42.22%。离体叶段接种白粉菌后1.5~2h、6~7h取样,在相差显微镜下观察白粉菌孢子萌发过程,发现这几种硅制剂对白粉菌孢子初生芽管(PGT)的形成几乎没有影响,但对附着胞(AM)的形成有较大影响,其中以二氧化硅纳米粒子溶胶对AM的影响最大。     

小麦离体叶段鉴定白粉病抗性方法的研究

１９９０年４月至１９９４年４月对小麦离体叶段鉴定白粉病抗性方法进行了研究。结果表明：（１）在灭菌条件下，以在培养皿中垫两层滤纸，用６ＢＡ作保绿主，超过人主至进行鉴定效果较好。（２）保绿剂的浓度低，发病快、退绿早，反之反病慢、退绿晚。其最适浓度是：苗期６ＢＡ为６０－１００ｐｐｍ、苯咪唑为６０ｐｐｍ ；成株期６ＢＡ以８０－１５０ｐｐｍ为佳。（３）份病快、退绿迟的角度出发，鉴定材料以株龄小、叶龄短的初展     

2008年我国主要麦区白粉菌群体对三唑酮和喹氧灵的敏感性监测

采用拌种离体叶段法对我国6个省(市)分离的小麦白粉菌108个和104个单孢堆菌株分别对三唑酮和喹氧灵的敏感性进行了测定,并对两者之间的交互抗性进行分析。结果表明,供试菌株对三唑酮的平均EC50为94.34mg/L,平均抗性水平达45.14倍,有97.25%菌株产生了抗性,其中高抗菌株(抗性水平40)占35.19%,中抗菌株占55.56%。河北菌株的抗性水平明显高于其他五省。小麦白粉病菌群体对喹氧灵的敏感基线为0.0059mg/L,且与三唑酮无交互抗性。此研究信息可为小麦白粉病抗药性持续治理措施的制定以及杀菌剂生产和使用策略提供依据。     

不同小麦品种对苯磺隆耐药性差异及其机理

室内用砂培法测定11种小麦品种对苯磺隆的相对敏感性,其敏感性有较大差异.碧玛4号、维麦8号对苯磺隆有很强的耐药性,IC50可分别达到502.6和409.3aiμg/kg,济1 3号为156.9aiμg/kg,鲁麦22号、黄县大粒对苯磺隆较为敏感,IC50低于45.0 aiμg/kg.以上5种小麦离体ALS对苯磺隆的敏感性没有明显差异,敏感品种黄县大粒IC50为154.2nmol/L,甚至较维麦8号149.3nmol/L略高.ALS活体试验表明,小麦可以很快恢复苯磺隆对ALS活性的抑制,且耐药型品种恢复能力较强,碧玛4号、维麦8号ALS恢复活性只需1.5天,敏感品种需3天.碧玛4号、维麦8号除草剂解毒酶系GSTs相对于敏感品种对苯磺隆有较大的反应幅度和较短的反应时间,第2天就分别达到1.46、1.42的峰值,而济13号、鲁麦22号、黄县大粒变化幅度较小,第3天才达到峰值,活性分别为1.39、1.33和1.32.研究表明,小麦各品种对苯磺隆的耐药能力产生差异的主要原因之一是小麦GSTs对苯磺隆的代谢所致,而与小麦ALS对苯磺隆的敏感程度无关.     

哈茨木霉菌BM6对小麦白粉病的防治研究

研究哈茨木霉菌BM6对小麦白粉病菌的拮抗作用和对温室盆栽苗小麦白粉病的防治效果,以及对小麦叶片中活性氧、木质素和丙二醛含量的影响。结果表明,哈茨木霉菌BM6发酵液对小麦白粉菌孢子萌发有明显的抑制作用,抑制率为84.26%,对小麦白粉病的防效可达51.59%。在哈茨木霉菌BM6发酵液处理小麦叶片后,提高了活性氧活性、木质素和丙二醛的含量,分别在第1天、5天和第3天出现高峰值。说明哈茨木霉菌BM6发酵液诱导引起小麦叶片活性氧迸发、木质素和丙二醛含量的升高,进而增强了小麦的抗病性。     

太子参叶斑病抗性诱导因子筛选

为筛选诱导太子参产生对叶斑病抗性的诱导因子,在离体培养条件下,用水杨酸、草酸、壳聚糖、磷酸氢二钾、亚硒酸钠和太子参叶斑病粗毒素液这6种因子诱导处理太子参组培苗,在1～7d内测定叶片相关酶活性的变化。诱导培养7d后,用太子参叶斑病粗毒素液对组培苗进行离体叶片针刺接种抗性鉴定,结果表明,诱导处理后能明显增强太子参叶片内POD、PPO和PAL的活性;6种因子均能诱导太子参对叶斑病产生抗性,以190mg.L-1和380mg.L-1草酸的诱抗效果较好,分别达到76.1%和74.7%,极显著高于其它诱导因子的诱抗效果。     

两种候选甲氧基丙烯酸酯类杀菌剂对黄瓜霜霉病的作用方式

20%唑胺菌酯EC、20%SYP-3998 SC是甲氧基丙烯酸酯类候选杀菌剂,为探索两药剂对黄瓜霜霉病的作用方式,采用盆栽植株喷雾-叶碟法、叶碟喷雾法、盆栽植株喷雾-叶碟法分别测定两药剂对黄瓜霜霉病的保护、治疗及持效期,并采用离体叶片法、叶碟法测定二者对黄瓜霜霉病的铲除作用.结果表明:20%唑胺菌酯EC和20%SYP-3998 SC具有良好的保护、治疗及铲除作用.两药剂的铲除作用表现在能抑制黄瓜霜霉病菌病斑扩展、孢子囊产生及孢子囊再侵染,与孢子囊混合接种能显著降低孢子囊的致病性.此外,20%唑胺茵酯EC和20%SYP-3998 SC具有7～10天的持效期;20%唑胺茵酯EC预防、治疗、铲除效果及持效性均优于20%SYP-3998 SC及对照药剂25%嘧菌酯SC.     

三个小麦新品系抗白粉病基因分析

 用4个具有不同毒力的小麦白粉菌生理小种,分别接种5个小麦品种(系)半双列杂交的F₁、F₂和BC₁F₁群体的幼苗离体叶段,初步鉴定出野二燕3号具有1对抗1号和11号小种的显性抗病基因;JYP-2具有2对独立的显性抗病基因,其中1对基因抗1、11和311号小种,另1对基因只抗1和11号小种;贵农21号具有2对显性抗病基因,其中1对抗311和313号小种,另1对只抗1和11号小种,这对基因与JYP-2具有的抗1和11号小种的基因是相同的。3个小麦新品系共鉴定出4对不同的抗病基因。本文还讨论了采用幼苗离体叶段接种,同一批单株接种2个以上小种,定单株编号,记载和统计的方法,在抗白粉病基因分析中的作用。     

Hymenopteran Parasitoids on Fruit-infesting Tephritidae (Diptera) in Latin America and the Southern United States: Diversity, Distribution, Taxonomic Status and their use in Fruit Fly Biological Control

We first discuss the diversity of fruit fly (Diptera: Tephritidae) parasitoids (Hymenoptera) of the Neotropics. Even though the emphasis is on Anastrepha parasitoids, we also review all the information available on parasitoids attacking flies in the genera Ceratitis, Rhagoletis, Rhagoletotrypeta, Toxotrypana and Zonosemata. We center our analysis in parasitoid guilds, parasitoid assemblage size and fly host profiles. We also discuss distribution patterns and the taxonomic status of all known Anastrepha parasitoids. We follow by providing a historical overview of biological control of pestiferous tephritids in Latin American and Florida (U.S.A.) and by analyzing the success or failure of classical and augmentative biological control programs implemented to date in these regions. We also discuss the lack of success of introductions of exotic fruit fly parasitoids in various Latin American countries. We finish by discussing the most pressing needs related to fruit fly biological control (classical, augmentative, and conservation modalities) in areas of the Neotropics where fruit fly populations severely restrict the development of commercial fruit growing. We also address the need for much more intensive research on the bioecology of native fruit fly parasitoids.     

Brief Guide for Authors

正Journal of Arid Land(JAL)is an international journal(ISSN 1674-6767;CN 65-1278/K)for the natural sciences,sponsored by the Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences and Science Press.It is published by Science Press and Springer-Verlag Berlin Heidelberg bimonthly.JAL publishes original,innovative,and integrative research from arid and semiarid regions,ad     

The parasitoid complex ofLiriomyza cicerina on chickpea (Cicer arietinum)

Liriomyza cicerina (Diptera: Agromyzidae) is an important pest on chickpea in Turkey. The objective of this study was to determine the parasitoids and rates of parasitism ofL. cicerina on chickpea (Cicer arietinum L.) during the 2005 and 2006 seasons in ?anl?urfa province, Turkey. Leaves with mines were sampled weekly and kept in the laboratory to observe and count emerging leafminer and parasitoid adults. Eight parasitoid species were collected: the braconidsOpius monilicornis Fischer andOpius tersus Foerster and the eulophidsDiaulinopsis arenaria (Erdös) andNeochrysocharis formosa (Westwood), which occurred in both the winter and summer seasons;Diglyphus crassinervis Erdös,Neochrysocharis ambitiosa Hansson,Neochrysocharis sericea (Erdös) andPediobius metallicus (Nees), which occurred only in the summer growing areas.Diaulinopsis arenaria was the predominant parasitoid with 4–7.7% parasitism rate whileN. ambitiosa andO. monilicornis were the second and third most predominant species. The results of these trials show that sinceDia. arenaria occurred throughout every season, it could potentially be used for control of the leafminerL. cicerina.     

Plant–herbivore asynchrony necessitates augmentative releases of the exotic beetle,Zygogramma bicolorata,to enhance the biological control of P arthenium hysterophorus

Systematic information on the quantitative impact of Z ygogramma bicolorata on the biology of P arthenium hysterophorus is crucial as the seeds of this weed continue to germinate from the accumulated soil seed bank throughout the year in the form of different germinating flushes, while the activity of the beetle ceases during winter as it enters diapause. Therefore, plant–herbivore interactions need to be explored to develop predictions of the overall impact of the introduced beetle on the weed. The findings revealed that defoliation by Z . bicolorata had a significant impact on the plant height, density and flower production in flushes F ₃, F ₄ and F ₅, but not in F ₁ and F ₂ that exhibited longer periodicity, profuse branching, a longer flowering period and maximum flower production and contributed mostly to the existing seed soil bank. Therefore, total depletion of the existing soil seed bank was not possible. Consequently, the effect of augmentative field releases of laboratory‐reared beetles was explored on F ₁ and F ₂ in February for three consecutive years (2011–2013). Before initiating the trial, random soil samples were taken from the plots that were assigned to the paired treatments (i.e. with the beetle and without the beetle [insecticide‐treated]) and it was found that the seed bank in those samples did not differ. The single release of Z . bicolorata adults at five per plant at the six‐leaf stage significantly reduced the soil seed bank, compared to without the biocontrol agent, irrespective of the flushes at the end of the season.     

Effects of the saprophytic leaf mycoflora on growth and productivity of winter wheat

The effects of the saprophytic mycoflora and its interference with cereal aphids on growth and yield of winter and spring wheat was studied in field experiments in 1980, 1981 and 1982.Yields varied between 5000 and 8000 kg dry matter of kernels per ha. The effect of the saprophytic mycoflora on yield was determined in different treatments: A) no control measures against cereal aphids and saprophytic and necrotrophic fungi, B) no control of cereal aphids, control of saprophytic and necrotrophic fungi, C) control of cereal aphids and control of saprophytic and necrotrophic fungi, D) control of cereal aphids and stimulation of saprophytic mycoflora and E) control of cereal aphids, no control of saprophytic and necrotrophic fungi nor stimulation of saprophytic mycoflora.Considerable differences in top densities of saprophytic mycoflora (10 times as large in A and D as in B and C) were determined. The consequences of these differences for the growth and productivity of wheat were minor. A negative effect of saprophytic mycoflora on the yield could not be detected in 1981 and 1982, whereas a small positive significant effect was found in 1980. This stimulation may have been due to competition between necrotrophic fungal pathogens and saprophytic mycoflora. As a result of favourable weather conditions necrotrophic fungal pathogens were very numerous in 1980 and could form an important yield reducing factor. Yield levels may effect the importance of the necrotrophic and saprophytic mycoflora as yield reducing factors. Additionally, in the presence of aphid honeydew captafol was found to be relatively ineffective against saprophytic fungi.     

Relationship Between Production of the Phytotoxin Prehelminthosporol and Virulence in Isolates of the Plant Pathogenic Fungus Bipolaris sorokiniana

A gas chromatographic method was developed to quantify the phytotoxin prehelminthosporol, which is a sesquiterpene metabolite of the plant pathogen Bipolaris sorokiniana. The toxin was extracted from mycelium or culture filtrates, pre-cleaned using solid phase extraction, and analyzed by gas chromatography as a trimethylsilyl-derivative. The detection limit of the method was 5ngl^–1 (signal to noise ratio 4:1) which corresponds to ca. 15ng prehelminthosporol per mg dry weight of mycelium or 15ng prehelminthosporol per ml culture filtrate. The total amount of prehelminthosporol (mycelium plus culture filtrate) increased with cultivation time when examined in six isolates of B. sorokiniana after 6, 9, 12 and 15 days of incubation. The screening experiment of 17 isolates for prehelminthosporol production after 8 days of incubation revealed significant differences in the toxin production between the isolates. The isolates with low toxin production had lower virulence towards barley roots compared to those with higher production of the toxin. However, the virulence did not increase with prehelminthosporol level among the high producing isolates. Prehelminthosporol was also analyzed in a number of related Bipolaris and Drechslera species. In addition to B. sorokiniana, three out of six Bipolaris species (B. setariae, B. zeicola, B. victoriae) produced prehelminthosporol, which indicates that ability to produce prehelminthosporol is conserved among closely-related Bipolaris species.     

Effect of botanical insecticides and bacterial toxins on the gut enzyme of the rice leaffolderCnaphalocrocis medinalis

The effect of botanical insecticides and bacterial toxins on gut enzyme activity of larvae of the rice leaffolderCnaphalocrocis medinalis (Guenée) (Insecta: Lepidoptera: Pyralidae) was investigated. Gut enzyme activities were affected by botanical insecticides and bacterial toxin individually and in combination. When fed a diet of rice leaves treated with botanical insecticides and bacterial toxins, in bioassays the activities of gut tissue enzymes — acid phosphatases (ACP), alkaline phosphatases (ALP) and adenosine triphosphatases (ATPase) — of rice leaffolder larvae were affected. When combined, the effect was more severe at a low concentration. Larvae that were chronically exposed to botanical insecticides and bacterial toxins showed a reduction in weight (59–89%) and exhibited a significant reduction in ACP, ALP and ATPase activities. The combination ofBacillus thuringiensis kurstaki and botanical insecticides caused a decrease of twofold in enzyme activity even at reduced concentration. A synergistic effect was found when botanical insecticides and bacterial toxins were combined at low doses. These effects were most pronounced in early instars. Clear dose-response relationships were established with respect to enzyme activity. In conclusion: (i) biopesticides are relatively safe and biodegradable; (ii) a synergistic effect of botanical insecticides and bacterial toxins was found; (iii) less expensive, readily available and naturally occurring biopesticides could be an alternative for organic and inorganic pesticides in controlling RLF. http://www.phytoparasitica.org posting Sept. 28, 2004.