花生条纹病毒(PStV)的媒介蚜虫种类及传毒效率研究

花生条纹病毒(Peanut Stripe virus PStV)是一种蚜传病毒.通过田间普查和抽样鉴定,初步明确了花生田主要蚜虫种类,其中优势种类与生态类型有关。棉花、花生邻作区以棉蚜为主,麦套花生和春花生区以麦长管蚜为主.单蚜接种试验表明定居蚜和许多迁飞过路蚜均可传播PStV,其传毒效率可用传毒贡献大小表示,传毒效率较高的有豆蚜、麦长管蚜和桃蚜,传毒贡献分别为40％、28％和16％。     

大豆花叶病(SMV)若干抗性鉴定指标分析

本文通过40个大豆品种的抗大豆花叶病鉴定,阐述了种传率、褐斑率和成株抗性三个抗性鉴定指标及相互关系。结果表明:种传率、褐斑率、成株抗性分别受不同基因控制。植株感染病后,任一指标为抗性,三项指标间不存在相关性。病株种子出苗率(种子活力)下降主要受种传率影响,与褐斑率、病情指数关系不大。在田间自然传毒情况下,褐斑率、种传率均随成熟期的推迟而加重。这是原始病株(带毒种子产生的病苗)、蚜虫消长及在同一时间内,不同熟期品种生长发育期不同所致,不能反映品种本身的抗性水平。     

中国西北地区麦二叉蚜与禾谷缢管蚜对小麦黄矮病传毒能力的分析

为了研究中国西北地区蚜虫对小麦黄矮病的传毒能力,为西北地区防治小麦黄矮病提供参考依据,常温条件下在温室大棚用盆栽小麦做传毒试验,以接种不同数量有毒蚜的小麦苗作为处理,接无毒蚜的小麦苗作为对照.传毒3 d后,在接种麦苗上喷洒药剂彻底杀死蚜虫,充分发病后观察记录小麦黄矮病的发病情况.结果表明,中国西北地区小麦黄矮病的优势介体是麦二叉蚜,但禾谷缢管蚜的传毒能力比以前有所提高.关中地区禾谷缢管蚜的传毒力高于河西地区禾谷缢管蚜的传毒力;三个地区(关中地区、渭北地区、河西地区)麦二叉蚜的传毒力都较高,差别不明显.三个地区两种麦蚜的成蚜传毒力普遍高于其若蚜的传毒力.     

花生条纹病毒在芝麻上流行研究初报

调查和试验结果说明：感染ＰＳｔＶ的花生是芝麻黄花叶病毒病主要初浸染源．桃蚜传毒效率最高，为３５％，豆蚜、大豆蚜和棉蚜传毒效率均很低．病害流行与蚜虫发生密切相关．供试的１０个芝麻栽培品种均不抗病，但存在一定成株期抗性。自花生条纹病毒（ＰＳｔＶ）感染的芝麻病株上收获的种子，种植后未发现病毒种传现象。     

大小麦两种土传病毒病害的轮茬发病观察

在我县沿海地带的冈东、上冈、草埝的乡镇及沿海辐射地域里下河地区,从2 0世纪80年代以来因大小麦的品种更新和免耕麦、套寄麦的麦作耕作制度的变革,随之发生大麦黄花叶病(Barleyyellowmosaicdisease)和小麦发生梭条斑花叶病(WSSMV) 〔1〕,这两种病毒病害严重影响大小麦经济产量和品质,一般减产30 %左右;而这两种病毒病害又都是土壤传播,以土壤中的禾谷多粘菌(PolrmyxaqraminisL)为介体的真菌传毒,真菌本身不致病,也不引起任何症状〔2〕。我们多年来对大小麦这两种病害的轮茬种植进行试验观察,探索发病规律和栽培防治。1　材料与方法1 1…     

甜菜种株的枝条嫁接

甜菜种株的枝条嫁接亦可称为“苔接”,是对甜菜进行无性杂交获得嵌合体的一种方法。甜菜的丰产、高糖和抗病等优良性状可望利用嫁接这种简便方法将其综合于同一个体,进而培育出优良的品种,这在理论和实践上都是一个值得探索的问题。在植物病毒的传毒试验方面嫁接同样也是一种很有效的方法。     

胡椒主要病害识别与防治技术

对胡椒瘟病、胡椒细菌性叶斑病、胡椒花叶病和胡椒根结线虫病等四种主要胡椒病害的症状、病原、发生规律、防治措施进行综述。     

苎麻花叶病传播方式及防治研究

研究表明：苎麻花叶病是不能通过土壤、种子及机械播种传病，而可由昆虫、嫁接及种根、压牺、嫩梢等无性繁殖材料传病的病毒性病害。鉴定了从国内外征集的９４３份苎麻种质资源，结果表明苎麻品种间具有明显抗病性差异，筛选出圆叶青、黑皮蔸、红皮小麻等抗病良种２０余份。并提出了建立良种基地、采用地病繁殖材料、推广抗病品种为主、治虫防病为辅的综合防治措施。     

麦类黄花叶病的发生及防治对策

由禾谷类多粘菌为媒介的麦类土传病毒病有三种.其中大麦黄花叶病(亦译怍大麦条纹萎缩病)多发生在大麦上,对啤酒大麦及六棱大麦品种鹿岛危害较大;小麦黄花叶病多发生在小麦上,对小麦品种"农林61"和"福穗"危害较大;小麦条纹(纹枯)病不但危害啤酒大麦,同时会对大麦和小麦造成危害,并能与黄花叶病重复感染.茨城县1985年麦类黄花叶病受害面积占三麦总栽培面积的55%.此病危害性很大,目前尚无有效防治药剂.本文主要介绍播种期、抗病品种及大、小麦轮作方面的最新防治知识.     

苎麻花叶病传播方式及防治研究

研究表明：苎麻花叶病是不能通过土壤、种子及机械播种传病，而可由昆虫、嫁接及种根、压条、嫩梢等无性繁殖材料传病的病毒性病害。鉴定了从国内外征集的９４３份苎麻种质资源，结果表明苎麻品种间具有明显抗病性差异，筛选出了圆叶青、黑皮蔸、红皮小麻等抗病良种２０余份。并提出了建立良种基地、采用无病繁殖材料、推广抗病品种为主、治虫防病为辅的综合防治措施。     

Integrated management of Phytophthora capsici on bell pepper by combining grafting and compost treatment

In 2010 and 2011 an initial set of trials were carried out in order to evaluate the susceptibility of rootstocks used for grafting bell pepper (Capsicum annuum L.) in Italy to Phytophthora capsici, in comparison with widely used cultivars of pepper. In a second set of trials carried out in 2011 and 2012, grafting bell pepper onto resistant or partially resistant rootstock was combined with the use of compost-amended soil, to control Phytophthora blight. Trials were carried out in artificially or naturally infested soil, using five bell pepper cultivars (Fenice, Sienor, San Marco, Fiume, Cuneo) as susceptible not-grafted controls. In three trials, carried out in the presence of soil artificially infested with P. capsici, disease incidence in control plots ranged from 73 to 100% for the cvs. Cuneo and Fiume. Both cvs. Cuneo and Kaiman grafted on “Tecnico F1” rootstock provided complete control of P. capsici. A lower disease control, on the same cultivar, was provided by “Robusto” and “Capsifort”. On the cv. Fiume, “Terrano” provided complete control of the disease. By grafting all cultivars on “Robusto”, “Brutus”, “Snooker” and “Capsifort” a disease reduction by 68%–93%, 86%–100%, 67%–100% and 55%–78%, respectively, was provided. The general linear model analysis showed that for trials carried out under natural infestation the addition of compost to the soil, as well as the interaction of compost-amended soil with grafting, were significant factors influencing disease incidence reduction. The effect of grafting was a significant factor in reducing the percentage of diseased plants in all the trials. The addition of compost to the soil resulted in an effective and low-cost disease management solution, particularly when combined with susceptible not-grafted hybrids of bell pepper or when partially resistant rootstocks were used.     

Effect of cyantraniliprole on feeding behavior and virus transmission of Frankliniella fusca and Frankliniella occidentalis (Thysanoptera: Thripidae) on Capsicum annuum

The anthranilic diamide insecticide cyantraniliprole was previously shown to reduce transmission of Tomato spotted wilt virus (TSWV) to pepper, Capsicum annuum, by Frankliniella fusca but not Frankliniella occidentalis. This study examines the effects of cyantraniliprole and imidacloprid on thrips feeding using electrical penetration graphing (EPG), and on TSWV transmission in field cage studies. Some antifeedant responses were observed in the EPG studies when thrips fed on cyantraniliprole- and imidacloprid-treated plants; however, these responses were variable between species and among the 2, 6, and 10 day post-treatment time intervals during which feeding behavior was observed. Cyantraniliprole significantly reduced the probability of TSWV infection when spread by F. fusca in field-grown pepper when viruliferous thrips were released 7 days but not when released at 14 days after the insecticide treatment in one of 2 field trials. In the second trial cyantraniliprole significantly reduced the probability of infection when F. fusca were released 14 days but not 7 days after treatment. In both years, imidacloprid prevented or significantly reduced transmission of TSWV by F. fusca in field-grown pepper when viruliferous thrips were released 7 days and 14 after treatment. In one of two years, cyantraniliprole significantly reduced the incidence of TSWV in field-grown pepper that was spread by F. occidentalis when viruliferous thrips were released 7 days after the insecticide treatment, but not 14 days after the treatment. Imidacloprid did not reduce the incidence of TSWV in field-grown pepper when viruliferous F. occidentalis were released. Although these studies demonstrate that probing behavior of these thrips species is altered on cyantraniliprole-treated pepper plants, results of field cage studies did not consistently show a reduction in incidence of TSWV-infected plants.     

Screening of endophytic bacteria and evaluation of selected isolates for suppression of burrowing nematode (Radopholus similis Thorne) using three varieties of black pepper (Piper nigrum L.)

Radopholus similis is a serious threat to black pepper (Piper nigrum L.) cultivation being the main causal organism of slow decline disease. Because of its migratory nature most fungal and bacterial antagonists are ineffective in suppressing R. similis. The presence of a number of endophytic bacteria in black pepper tissues has been proved in earlier studies. This study was undertaken to evaluate the bacteria isolated from black pepper for suppressing R. similis. In vitro and in vivo screenings were used initially to identify the efficient strains of endophytic bacteria that suppress R. similis. Seventy four isolates of endophytic bacteria obtained from black pepper were screened against R. similis by various bioassays. Results of the in vitro experiments were inconclusive and did not match the rest of the studies. However, six isolates were short-listed based on the preliminary in vivo screening and further tested in an evaluation trial using three varieties of black pepper. Irrespective of the varieties, significantly higher nematode suppression was observed with one isolate (TC 10) followed by another (BP 17). These isolates were identified to the species level by sequence analysis of the 16S rRNA gene. The results showed that these isolates shared 99% identity with Bacillus megaterium and Curtobacterium luteum, respectively. More studies are required to understand their mode of action as well as the dose–response relationship with nematodes.     

胡椒栽培种与野生近缘种嫁接技术调查

通过对胡椒野生近缘种蒌叶Piper betle L.作砧木、胡椒Piper nigrum L.栽培种Kuching作接穗的嫁接技术进行调查，调查结果表明：胡椒栽培种与胡椒野生近缘种嫁接亲和力强，嫁接成活率高，嫁接植株主蔓粗壮，生长迅速，生态适应能力明显增强。     

Aphid abundance and potato virus y transmission in imidacloprid-treated potatoes

Imidacloprid is a commonly used insecticide that is highly effective in controlling insect pests of potato. The relatively high cost of imidacloprid provides commercial growers with a strong incentive to reduce field application rates. In the present study, we investigated the impact of reduced imidacloprid rates on aphid abundance and potato virus Y transmission within potato fields. Infurrow applications of imidacloprid provided better aphid control even at a reduced rate when compared to threshold-based foliar applications, but did not suppress the spread of the non-persistently transmitted potato virus Y. Virus transmission was significantly decreased in foliar-sprayed plots, possibly because foliar applications incapacitated aphid vectors probing or feeding on infected plants. Despite these generally encouraging results, we still observed 2.3 to 2.7 fold increase in virus infection at foliar-treated plots at the end of the growing season.     

海南槟榔黄化植原体分子检测及其系统发育关系研究

由植原体引起的槟榔黄化病是海南特色经济作物槟榔种植上的一种毁灭性病害。本研究通过PCR扩增测序、序列多重比对和系统发育分析,对海南部分代表性地区槟榔致死性病原植原体的序列信息与系统发育关系进行检测分析。结果表明：本研究检测的保亭、屯昌、万宁等海南部分代表性地区的槟榔黄化植原体的16S rDNA序列一致;BLAST分析表明各株系16S rDNA与16SrI组植原体同源性为100%。序列多重比对分析表明,本研究各槟榔黄化植原体株系与海南苦棟丛枝、长春花绿变、马松子变叶、辣椒黄化皱缩、蛇婆子丛枝、细圆藤丛枝和日本洋葱黄化、美国翠菊黄化等植原体同源性为100%;与已报道的海南万宁、印度、海南三亚的槟榔黄化植原体16S rDNA序列同源性分别为99.9%、99.9%、99.8%。系统发育分析表明,本研究槟榔黄化植原体与海南苦棟丛枝、长春花绿变、马松子变叶、辣椒黄化皱缩、蛇婆子丛枝、细圆藤丛枝等株系聚于一个分枝,支持率为100%。此外,在发病槟榔叶片、花穗、心叶等组织部位均可检测到植原体。研究结果表明,海南槟榔黄化植原体与海南苦棟丛枝、长春花绿变、马松子变叶、辣椒黄化皱缩、蛇婆子丛枝、细圆藤丛枝等植原体株系的同源性极高,槟榔黄化病很可能会以这些寄主植物作为病原传播载体进行传播扩散。     

中国胡椒疫霉种及交配型的研究

1982—1990年,从海南、云南、广东省13个县(市)的60多个发生胡椒瘟病的胡椒园采集大量带菌材料的样本,经分离获得65个疫霉菌株,并鉴定为寄生疫霉(Phytophthara parasitica Dast.)和竦淑疫霉(P.capsici Leon.)两个种。这是国内首次报道。在65个菌株中,寄生疫霉为34株,辣椒疫霉为31株,两者的比例接近1:1。这两个种对中国主要胡椒植区的胡椒瘟病具有同等的重要性。所有菌株的支配型中,两个种都以A~2占大多数,而且都存在个别同宗配合和中性菌株。     

To what extent does Tobler's 1st law of geography apply to macroecology? A case study using American palms (Arecaceae)

Background

Competitive displacement of a weakly virulent pathogen strain by a more virulent strain is one route to disease emergence. However the mechanisms by which pathogens compete for access to hosts are poorly understood. Among vector-borne pathogens, variation in the ability to infect vectors may effect displacement. The current study focused on competitive displacement in dengue virus serotype 3 (DENV3), a mosquito-borne pathogen of humans. In Sri Lanka in the 1980's, a native DENV3 strain associated with relatively mild dengue disease was displaced by an invasive DENV3 strain associated with the most severe disease manifestations, dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS), resulting in an outbreak of DHF/DSS. Here we tested the hypothesis that differences between the invasive and native strain in their infectivity for Aedes aegypti mosquitoes, the primary vector of DENV, contributed to the competitive success of the invasive strain

Results

To be transmitted by a mosquito, DENV must infect and replicate in the midgut, disseminate into the hemocoel, infect the salivary glands, and be released into the saliva. The ability of the native and invasive DENV3 strains to complete the first three steps of this process in Aedes aegypti mosquitoes was measured in vivo. The invasive strain infected a similar proportion of mosquitoes as the native strain but replicated to significantly higher titers in the midgut and disseminated with significantly greater efficiency than the native strain. In contrast, the native and invasive strain showed no significant difference in replication in cultured mosquito, monkey or human cells.

Conclusion

The invasive DENV3 strain infects and disseminates in Ae. aegypti more efficiently than the displaced native DENV3 strain, suggesting that the invasive strain is transmitted more efficiently. Replication in cultured cells did not adequately characterize the known phenotypic differences between native and invasive DENV3 strains. Infection dynamics within the vector may have a significant impact on the spread and replacement of dengue virus lineages.     

不同胡椒粉中胡椒碱的含量比较

采用高效液相色谱法(HPLC)和紫外分光光度法(UV)测定黑胡椒、胡椒根、市售胡椒粉和用不同浸泡液浸泡脱皮的白胡椒粉中的胡椒碱含量。结果表明：黑胡椒粉、2种市售胡椒粉和白胡椒粉中胡椒碱含量不同；果＞根、白胡椒＞黑胡椒、盐水浸泡＞河水浸泡＞醋浸泡、西安胡椒粉＞海南胡椒粉。说明不同的胡椒粉胡椒碱的含量不同，这可以为胡椒的质量控制提供比较有用的参考。     

Navelina ISA 315: A cultivar resistant to citrus variegated chlorosis

Citrus variegated chlorosis (CVC), caused by Xylella fastidiosa, is a bacterial disease of great importance to the Brazilian citrus industry. CVC is transmitted by grafting and by leafhoppers of the Cicadellidae and Cercopidae families. There is little information about CVC tolerant sweet orange cultivars (Citrus sinensis L. Osbeck). However, previous studies have indicated some resistance to CVC in the ‘Navelina ISA 315’ cultivar. Based on such information, this study has been carried out to determine the resistance of ‘Navelina ISA 315’ to CVC observing disease symptoms in the field and in the greenhouse, associated with the presence and quantitation of X. fastidiosa in plant tissue by PCR and quantitative real time PCR (qPCR). In agreement with previous information, the results show that ‘Navelina ISA 315’ is resistant to CVC, on the grounds that almost no symptoms and low bacterial concentrations were found.