Retention of Rice dwarf virus by Descendants of Pairs of Viruliferous Vector Insects After Rearing for 6 Years

ABSTRACT Rice dwarf virus (RDV) is characterized by its unusual ability to multiply in both plants and leafhopper vector insects and by its transovarial mode of transmission. Colonies of Nephotettix cincticeps, derived originally from pairs of leafhoppers infected with an ordinary strain of RDV, were maintained for 6 years in the laboratory and were found, at the end of this time, still to harbor RDV. Moreover, the isolate of RDV, designated RDV-I, obtained from these colonies retained the ability to infect rice plants. When we raised leafhoppers separately from eggs that had been placed individually on pieces of water-soaked filter paper and reared them in the presence of healthy rice seedlings, we found that all of these leafhoppers harbored RDV. This observation suggested that RDV-I had been maintained in the leafhoppers by transovarial transmission. Two further observations, namely, the low rate of acquisition of RDV by virus-free insect nymphs on symptomless plants on which viruliferous insects had been reared, and the fact that only 2 to 5% of plants had symptoms when rice seedlings were inoculated via RDV-I-viruliferous insects, confirmed that the maintenance of RDV-I by any other mode of transmission through plants and insects was unlikely. This efficient and long-term maintenance of RDV in a population of viruliferous insects might explain the prolonged duration of rice dwarf disease in the field, once there has been a serious outbreak.     

水稻橙叶病分子检测及其在华南地区的发生与分布研究

对华南地区水稻橙叶病(rice orange leaf disease)进行病原菌分子检测和病情发生与分布调查。结果表明,该病是一种由电光叶蝉(Inazuma dorsalis)和黑尾叶蝉(Nephotettix cinticeps)传播的植原体(Phytoplasma)引起的病害,早期感病植株在分蘖期全株叶片表现为橙黄色,不久干枯死亡,对水稻生产造成严重为害。电镜下观察,病株幼叶叶脉筛管细胞中存在大量植原体。巢式PCR可从来源于水稻病株及介体电光叶蝉和黑尾叶蝉DNA抽提物中获得单一扩增产物,PCR产物核苷酸序列与文献报道的水稻橙叶植原体16S r DNA序列(Gen Bank登录号:KR061356)同一率均为99.8%以上。2015年广东各主要稻区及海南中部和广西东南部均有该病发生与分布。     

Strepsipteran parasitism of white leafhoppers,Cofana spp. (Hemiptera: Cicadellidae) in lowland rice in Cote d'Ivoire

Three tests were conducted over a 2-year period in lowland irrigated rice fields on the WARDA Research Station at Bouake, Cote d'Ivoire, to obtain information on the strepsipteran parasitism of white leafhoppers, Cofana spectra and C. unimaculata. Rice cultivars were sampled with a sweep net to collect leafhoppers for determination of the relative abundance of the two leafhopper species and the effect of rice cultivar and rice crop age on the leafhopper populations and percent strepsipteran parasitism. Dissections of the leafhoppers were made to determine the relative number of the various parasitic stages in the leafhoppers. Cofana unimaculata populations were higher than those of C. spectra while C. spectra parasitism by Halictophagus australensis Perkins (Strepsiptera: Halictophagidae) was higher than that of C. unimaculata. In two tests, there was a relationship between length of rice cultivar duration and C. unimaculata populations with populations being highest on the short duration cultivars. On most cultivars there was no correlation between Cofana populations and percentage parasitism, nor was there a relationship between cultivar growth duration and percent parasitism. The number of the various stages of the parasite was similar in both Cofana species with the male pupal parasitic stage being most common.     

不同稻田生态系统中稻纵卷叶螟、稻飞虱及其天敌密度的差异

研究了施用化学农药防治害虫的常规管理稻田和充分发挥天敌自然控害作用为主要防治害虫措施的稻田生态系统内稻纵卷叶螟、稻飞虱及其天敌的发生消长动态,以明确不同稻田生态系统对稻区内主要害虫及其天敌的影响.结果显示,生态调控区稻田内稻纵卷叶螟和稻飞虱最大高峰期虫量仅分别为常规管理区的0.51倍和0.63倍;生态调控区稻周植被上稻纵卷叶螟和稻飞虱发生数量几乎为0,而常规管理区最大高峰期虫量分别达到 23.61头/10网和82.03头/10网.生态调控措施还可以显著增加天敌数量,生态调控区稻田内最大高峰期天敌数量为常规管理区的3.72倍,其稻周杂草上最大高峰期天敌数量为常规管理区的5倍以上;同时,天敌与稻纵卷叶螟和稻飞虱发生高峰期吻合度远高于常规管理区.说明生态调控措施能充分发挥稻田及周边非稻田生境的保益控害功能.     

水稻矮缩病的研究——Ⅱ.病害感染、发生和防治

水稻矮缩病的潜育期因气温、水稻生育期、介体黑尾叶蝉(Nephotettix cincticeps)的虫龄、性别等不同而异,一般为10～15天。水稻在分蘖初期到盛期最易感病,这些病株均不能抽穗结实;分蘖末期感染者,产量损失达80%以上。病毒在虫体内越冬,越冬代带毒成虫传毒给早稻,第2、3代带毒虫传毒给晚稻。第1、4代经卵带毒虫,还能分别引起早、晚稻再次侵染。以早栽双季晚稻和杂交晚稻发病最重,其主要感染期是在本田初期。以农业防治为基础,治虫防病抓适期的综合防治措施,能有效地控制病害流行。病区在连片种植的基础上,对早栽双季晚稻本田初期喷药治虫1～3次,能收到显著的防病效果。     

多物种共存系统中拟水狼蛛对三种稻虫的捕食作用

选择稻田蜘蛛优势种拟水狼蛛(Pirata subparaticus)和水稻主要害虫褐飞虱(Nilaparvata lugens)、白背飞虱(Sogatella furciferz)、黑尾叶蝉(Nephotettix cincticeps)组成多物种共存系统,运用二次通用旋转组合设计试验探讨蜘蛛对稻虫的控制作用,分析天敌与害虫间、害虫之间的相互作用关系,得到天敌对害虫的4个捕食量模型,其中拟水狼蛛对3种害虫的总捕食量模型为Y_4=28.143 6.375X_1 1.792X_2 1.625X_3-0.042X_4-4.754X_1~2-3.129X_2~2-1.629X_3~2-2.129X_4~2-0.188X_1X_2 0.063X_1X_3-0.438X_1X_4-0.188X_2X_3-0.438X_2X_4-1.438X_3X_4。对该模型的主效分析表明,天敌自身密度对捕食量的影响最大;其次是害虫密度的影响,其中褐飞虱对捕食量的影响较大,白背飞虱次之,黑尾叶蝉最小。害虫间的互作分析表明,白背飞虱同黑尾叶蝉间的交互效应对拟水狼蛛捕食作用的影响最强。     

水稻簇矮病的研究Ⅴ.病害的年际变化

 病区四个县和非病区一个县1976~1990年的调查、研究结果表明,水稻簇矮病毒(RBSV病害的发生、消长在年际间存在着很大的差异,这种差异随着稻株易感阶段介体叶蝉的种群数量及其传病潜能一一带毒率、亲和率和传毒天率的变化而变化。有的年份虽然介体叶蝉带毒率不高,但其绝对虫口密度大,也能导致病害的严重发生。     

Research priorities for rice pest management in tropical Asia: a simulation analysis of yield losses and management efficiencies

ABSTRACT A simulation study was conducted to assess the current and prospective efficiency of rice pest management and develop research priorities for lowland production situations in tropical Asia. Simulation modeling with the RICEPEST model provided the flexibility required to address varying production situations and diverse pest profiles (bacterial leaf blight, sheath blight, brown spot, leaf blast, neck blast, sheath rot, white heads, dead hearts, brown plant-hoppers, insect defoliators, and weeds). Operational definitions for management efficacy (injury reduction) and management efficiency (yield gain) were developed. This approach enabled the modeling of scenarios pertaining to different pest management strategies within the agroecological contexts of rice production and their associated pest injuries. Rice pests could be classified into two broad research priority-setting categories with respect to simulated yield losses and management efficiencies. One group, including weeds, sheath blight, and brown spot, consists of pests for which effective pest management tools need to be developed. The second group consists of leaf blast, neck blast, bacterial leaf blight, and brown plant-hoppers, for which the efficiency of current management methods is to be maintained. Simulated yield losses in future production situations indicated that a new type of rice plant with high-harvest index and high-biomass production ("New Plant Type") was more vulnerable to pests than hybrid rice. Simulations also indicated that the impact of deployment of host resistance (e.g., through genetic engineering) was much larger when targeted against sheath blight than when targeted against stem borers. Simulated yield losses for combinations of production situations and injury profiles that dominate current lowland rice production in tropical Asia ranged from 140 to 230 g m(-2). For these combinations, the simulated efficiency of current pest management methods, expressed in terms of relative yield gains, ranged from 0.38 to 0.74. Overall, the analyses indicated that 120 to 200 x 10(6) tons of grain yield are lost yearly to pests over the 87 x 10(6) ha of lowland rice in tropical Asia. This also amounts to the potential gain that future pest management strategies could achieve, if deployed.     

湖南水稻白翅叶蝉的研究

白翅叶蝉Erythroneura subrufa(Motschulsky)成虫与若虫均以刺吸口器刺进水稻叶片组织内吸取叶汁和叶绿素,被害初期,叶片上出现零星小白点,随后出现长短不一的点状白色斑条,受害严重的稻叶上满布白色斑纹,叶绿素丧失,叶片干萎。在稻叶蝉中除一点小叶蝉被害状出现小白点外,其他叶蝉为害水稻时,并不直接破坏叶绿素,亦不呈现白色斑纹,而是直接吸食叶液,使禾苗发黄而死。因而纠正了过去认为黑尾叶蝉、白翅叶蝉为害水稻后,都会造成叶片出现白色或褐色斑纹的报道。白翅叶蝉在湖南一年发生三代,在晚稻收割后以成虫迁向麦田、杂草等场所越冬,因其寿命很长,故长期不同世代交错。白翅叶蝉除为害水稻外,在初冬与早春还为害冬小麦。近年在湖南及我国南方部分稻区有回升趋势。     

水稻害虫上三种病原镰刀菌的研究

1979～1982年间,作者在对湖南水稻主要害虫病原微生物资源调查中,发现鳞翅目、同翅目和双翅目中的许多种害虫被镰刀菌属的串珠镰刀菌(Fusari-um moniliforme)、燕麦镰刀菌(F.avenaceum)及本色镰刀菌(F.Concolor)所寄生。尤其是在每年3～4月间对越冬螟虫尸体上的病原物分离中,镰刀菌占90%以上。用这些菌种对二化螟、大螟越冬幼虫进行生物测验,其寄生死亡率在50～100%之间;对褐稻虱和黑尾叶蝉的寄生率为50～80%。三种镰刀菌发酵物的浸提液对害虫都有一定的毒力,其中以燕麦镰刀菌的最强。用该菌在玉米粒上培养一年的发酵物,以湿重5克加水150毫升的浸提液饲养中华大蟾蜍的蝌蚪,3～4小时内全部死亡。用此液处理稻苗饲养二化螟幼虫,死亡率为64%左右;用处理的甘蓝叶饲喂菜青虫,死亡率为70%左右。将燕麦镰刀菌发酵物浸提液在-16℃下冷冻5～6天和在100℃时煮沸5～10分钟仍不丧失其毒力。     

Efficacy of Common Carp and Nile Tilapia as biocontrol agents of rice insect pests in the Philippines

Replicated field plot trials were carried out to evaluate the role of fish as biocontrol agents of insect pests of rice in the Philippines. Evidence from suction sampling, examination of fish gut contents, and rice plant damage assessment strongly suggest that Common Carp Cyprinus carpio (L.) and Nile Tilapia Oreochromis niloticus (L.) do significantly reduce the densities of stemboring moths and chironomid midges, while the abundance levels of other arthropods are not significantly affected. This impact by fish often was more important in the wet season when heavy rains and wind likely caused the arthropods to become dislodged from the plant and fall onto the water. Predation by fish was particularly evident during the first 45 days of the crop during the wet season when adult chironomid midge abundance was high. The fish gut content analysis revealed that all insect guilds are represented in the diet of both of the fish species regardless of whether the life-cycle of the arthropod prey is aquatic, semi-terrestrial, or terrestrial. Thus, fish in rice fields are part of the assemblage of natural enemies of rice pests. While fish alone cannot completely suppress rice pest populations below the economic threshold, their significant contribution should not be overlooked.     

不同稻区节肢动物群落中捕食者与猎物的种类与数量特征

根据在浙江富阳、江苏句容和河南郑州，对三种不同生态类型稻区节肢动物群落的系统调查，明确了捕食性天敌与其猎物在种类和数量上的相互作用以及季节动态方式。用经过原点的直线回归分析，捕食者的种类是猎物的１．５２５倍。从数量上看，猎物多于捕食者，二者平均比率约为１：４。捕食者与猎物之间具有跟随现象，但一般滞后７～１４天。优势种捕食者如黑肩绿盲蝽、狼蛛、微蛛及食虫沟瘤蛛对以白背飞虱、褐飞虱（富阳、句容）、黑尾叶蝉、灰飞虱（郑州）为主的害虫种群具有显著的控制效应，应注意保护利用。     

多抗性晚籼浙丽1号(6202)对几种主要病虫的抗性

作者等自1973年开始进行抗病虫水稻品种的研究工作,现已育成抗主要病虫害:褐飞虱、自背飞虱、黑尾叶蝉和稻瘟病的晚籼浙丽1号(6202)。组合为广塘矮/Mudgo//竹科2号。本文还就耕作制度尤其抗虫品种以及褐飞虱“生物型”与稻飞虱种群动态的关系进行了讨论,并查明当地褐飞虱田间优势种群目前尚属生物型1。     

农药混剂配比研究的一种实用寻优方法初探

以室内毒力测定技术为基础,提出了一种在研究农药复配制剂过程中筛选并表征最佳配比的实用方法,适用于杀虫剂的二元复配配比研究。在室内以稻黑尾叶蝉Nephotettix cincticeps 4龄若虫为供试昆虫,对仲丁威和乐果混配进行了最佳配比的筛选和验证,取得了理想的结果。     

Evidence for the physical integrity of flavescence dorée phytoplasmas purified by immunoaffinity from infected plants or leafhoppers and the plant pathogenicity of phytoplasmas from leafhoppers

Phytoplasmas were extracted from flavescence dorée-infected broadbean ( Vicia faba ) using a vacuole isolation medium, and were immunoaffinity purified from infected leafhoppers. Purified phytoplasmas from both host sources were immunolabelled and observed under the electron microscope. The infectivity of the purified phytoplasmas from leafhoppers was checked by injecting healthy leafhoppers which were then allowed to feed on healthy V. faba seedlings. The appearance of typical symptoms in these plants, and the positive results obtained in ELISA with extracts of some of the injected leafhoppers and with symptomatic V. faba , indicated that the purified phytoplasmas had retained their infectivity and had multiplied in the injected leafhoppers which had become infective. These results support a previous report that phytoplasmas purified by immunoaffinity chromatography are well preserved.     

The Major Insect Pests of Rice,Sugarcane and Jute in Bangladesh

Abstract

The insect pest problems of agriculture in Bangladesh have not been adequately studied or surveyed. Nevertheless some preliminary data are available to indicate the possible seasonal and annual abundance of the most important pests attacking rice, sugarcane and jute.     

南方水稻黑条矮缩病防控药剂的创制与应用

南方水稻黑条矮缩病是我国及越南等东南亚国家稻区水稻的重要病毒病。该病害潜隐性强、危害重、防控难度大,对水稻生成构成极大威胁。本文综述了南方水稻黑条矮缩病毒的基因组结构及功能、分子进化、病毒与植物寄主或媒介昆虫间的互作、测报技术、药剂创制和田间综合防控的研究进展,并对未来工作进行了展望与讨论。     

水稻矮缩病综合防治研究

防治双季晚稻矮缩病,采用连片种植,改进耕作栽培方法,选用抗(耐)病品种等农业技术措施,再在本田初期及时治虫1—3次,能达到80%以上的防病效果。不用农业防治,单在本田初期及时治虫1—3次防治效果为59.6%。但对小面积晚稻,在本田初期于介体昆虫迁飞高峰期及时治虫2—4次,防病效果也能达到80%以上。欲使晚稻后期的株发病率分别控制在1%、3%和5%以下,其本田初期防病治虫的指标是:当介体昆虫的带毒率为2.5%时,分别为每百株苗虫量4、12和22头;而当介体昆虫的带毒率为5%时,分别为每百株苗虫量2、6和10头。     

水稻覆膜旱作对病虫草害发生程度的影响

就覆膜旱作栽培方式对早稻和单季稻病虫草害、天敌、腐食者等的丰盛度与为害程度影响作了研究。结果表明,稻田覆膜旱作可显著降低早稻纹枯病的发生程度,与常规淹水对照稻田相比,覆盖旱作稻田纵卷叶螟为害率、灰飞虱和蚜虫类虫密度及杂草发生程度无显著差异,但螟虫为害加剧,施肥量仅对照田一半的覆膜田螟虫为害株百分率比对照田提高２．４％～８．５％。水稻覆膜旱作栽培方式和种植密度高低是影响寄生蜂和蜘蛛类密度的主要因子。     

水稻白背飞虱为害损失测定及防治指标研究

白背飞虱〔Sogatella furcifera(Horvath)〕是80年代以来我国最重要的害虫之一,白背飞虱种群发展与生态研究协作组组织全国9个单位于1986—1989年开展的为害损失测定及防治指标研究的结果表明,受害稻株谷粒千粒重下降,空瘪率增加,在前中期受害其稻穗总粒数和有效穗数减少;杂交稻受害后表现出较强的耐害和自身补偿能力;白背飞虱与褐飞虱混合种群为害时,产量损失大于单一白背飞虱种群为害时的损失。根据虫量与产量损失的预测模型,结合现行稻谷价格,产量水平,防治费用,经济效益以及天敌和防治风险等因素,本文提出了我国多数稻区现阶段白背飞虱允许为害损失率和不同稻区、不同生产水平的经济防治指标。