水稻矮缩病毒昆明分离物抗血清制备及免疫捕捉PCR检测

由水稻矮缩病毒(Rice dwarf viru S,RDV)引起的水稻矮缩病害,最早由日本报道,随后在东南亚等国以及我国的福建、云南等南方稻区普遍发生,云南主要发生于中部及南部地区[1].水稻在苗期至分蘖期感病后,植株矮缩,分蘖增多,叶片浓绿,僵直,出现白斑,生长后期病稻不能抽穗结实,在暴发流行年份可以引起水稻的严重减产.     

水稻条纹花叶病毒对介体电光叶蝉生长繁殖及取食行为的影响

【目的】由电光叶蝉Recilia dorsalis传播的水稻条纹花叶病毒(rice stripe mosaic virus, RSMV)目前在我国华南稻区大面积发生并对水稻生产造成严重危害。本研究旨在明确RSMV对介体电光叶蝉生长繁殖及取食行为的影响。【方法】通过生物学实验测定RSMV侵染后电光叶蝉的生长和生命表参数;利用刺吸电位(electrical penetration graph, EPG)技术比较携带和未携带RSMV的电光叶蝉成虫在健康水稻上的取食行为差异;采用Y型嗅觉仪测定电光叶蝉成虫对感染和未感染RSMV水稻的寄主选择倾向性。【结果】与无毒电光叶蝉相比,携带RSMV的电光叶蝉若虫发育历期延长,而若虫存活率、成虫羽化率、雌虫繁殖力和卵孵化率下降。无毒电光叶蝉成虫倾向于选择取食RSMV侵染的水稻,而带毒电光叶蝉成虫倾向于选择取食健康水稻。与无毒电光叶蝉相比,带毒电光叶蝉成虫取食健康水稻所产生的刺探波、障碍波和唾液分泌波次数和持续时间均显著增加,被动取食波和休息波次数减少但时间均延长。【结论】与无毒电光叶蝉相比,感染RSMV使带毒电光叶蝉若虫发育历期延长且不利于其种群的繁殖。R...     

水稻对黑尾叶蝉的抗性

目前,主要产稻国都在研究利用水稻抗性来防治黑尾叶蝉。因为它既能防治黑尾叶蝉对水稻的直接为害,又能防治由它传毒引起的病毒病——普通矮缩病、黄矮病、簇矮病和通格鲁病等。 农作物品种的抗虫性通常分不嗜性、耐害性和抗生作用三大类。利用抗生作用能最有效地压低虫口密度,减少传毒媒介。 具有抗生作用的水稻品种能使饲放的黑尾叶蝉成虫和各龄若虫迅速死亡(见表1、2)。使雌成虫产卵量明显降低(见表3)。     

水稻矮缩病毒昆明分离物抗血清制备及免疫捕捉PCR检测

由水稻矮缩病毒(Rice dwarf virus,RDV)引起的水稻矮缩病害,最早由日本报道,随后在东南亚等国以及我国的福建、云南等南方稻区普遍发生,云南主要发生于中部及南部地区[1]。水稻在苗期至分蘖期感病后,植株矮缩,分蘖增多,叶片浓绿,僵直,出现白斑,生长后期病稻不能抽穗结实,在暴发流行年份可以引起水稻的严重减产。RDV在分类上属于呼肠孤病毒科(Reoviridae)植物呼肠孤病毒属(Phytoreovirus)成员,病毒粒子为正十二面体球形结构,直径约为69.3nm,无刺突,无脂蛋白外膜包被,具有双层的蛋白衣壳[2]。病毒基因组由12条双链RNA片段组成,其中S8编…     

我国禾谷类病毒病的病原问题——Ⅺ.用酶联免疫吸附测定法检测水稻普矮病传毒昆虫带毒率

本文报道用酶联免疫吸附测定法(ELISA)检测水稻普通矮缩病传毒昆虫带毒率。用戊二醛二步法制备辣根过氧化物酶与抗血清丙种球蛋白的结合物,用ELISA法检测水稻普通矮缩病传毒昆虫——黑尾叶蝉388头,测定结果与常规生物接种测定比较,其符合率为92.7%。     

我国禾谷类病毒病的病原问题——Ⅺ.用酶联免疫吸附测定法检测水稻普矮病传毒昆虫带毒率

本文报道用酶联免疫吸附测定法(ELISA)检测水稻普通矮缩病传毒昆虫带毒率。用戊二醛二步法制备辣根过氧化物酶与抗血清丙种球蛋白的结合物,用ELISA法检测水稻普通矮缩病传毒昆虫——黑尾叶蝉388头,测定结果与常规生物接种测定比较,其符合率为92.7%。     

杂交水稻对黑尾叶蝉抗性的研究

<正> 在日本、朝鲜和我国,黑尾叶蝉Nephotettixcincticeps(Uhler)是水稻普通矮缩病和黄矮病的主要传毒媒介。所以,选育抗黑尾叶蝉的品种是“治虫防病”的一种有效途径。井上齐(1966)首先报道了水稻对黑尾叶蝉感受的品     

我国禾谷类病毒病的病原问题 Ⅳ.用血清学方法测定水稻普通矮缩病介体昆虫的带毒率

建立了一个用氯仿处理,聚乙二醇沉淀和差速离心提纯净化水稻普通矮缩病病毒的简便方法。纯化的制剂免疫兔子后获得的抗血清用环状沉淀法测定,一般效价在1:4000～1:16000。应用反向间接血凝反应测定经卵传毒黑尾叶蝉的带毒率,与生物测定结果相比,符合率约86%。     

我国禾谷类病毒病的病原问题——Ⅳ.用血清学方法测定水稻普通矮缩病介体昆虫的带毒率

建立了一个用氯仿处理,聚乙二醇沉淀和差速离心提纯净化水稻普通矮缩病病毒的简便方法。纯化的制剂免疫兔子后获得的抗血清用环状沉淀法测定,一般效价在1∶4000～1∶16000。应用反向间接血凝反应测定经卵传毒黑尾叶蝉的带毒率,与生物测定结果相比,符合率约86%。     

黑尾叶蝉对有机磷的抗性及增效机制的研究

黑尾叶蝉(Nephotettix cincticeps uhler)是我国水稻的主要害虫之一。它不仅刺吸稻株汁液直接危害水稻,而且还传播水稻普通矮缩病、黄矮病等病毒病,严重影响了水稻的稳产高产。长期以来对黑尾叶蝉主要是应用有机磷杀虫剂1605、马拉松、乐果等防治,其中马拉松效果尤为显著。但近年来,在用药水平高的地区普遍反映防治效果下降,不少地区     

Feeding of Cyclops vicinus (Uljanin) (Copepoda: Cyclopoida) in Lake Balaton on the basis of gut content analyses

Consumption of planktonic algae by Cyclops vicinus living in Lake Balaton were studied in eighteen feeding experiments during 1980–1981. Gut contents of 284 adult C. vicinus were analysed in comparison with the natural phytoplankton assemblage. Rates of algal cells elimination were also studied and compared to controles which did not contain animals. C. vicinus in Lake Balaton was found to be an omnivore.     

A comparison of the host preference of monarch butterflies (Danaus plexippus) for milkweed (Asclepias syriaca) over dog-strangler vine (Vincetoxicum rossicum)

Observations in the field indicate that monarch butterflies will oviposit on dog‐strangler vine, an invasive introduced species in the same family as milkweed (Asclepias spp.), the principal larval host of monarchs. The potential impact of this behaviour depends on the strength of the preference of monarch adults to oviposit on these two hosts and the relative ability of larvae to survive on each. We determined the preference for milkweed vs. dog‐strangler vine of ovipositing adults and first instar larvae in choice and no‐choice tests. We also compared the ability of larvae to consume, develop, and survive on either host. In the presence of both hosts, adults exhibited a strong preference to oviposit on milkweed over dog‐strangler vine (mean 80.7 eggs compared to 0.4 eggs over 48 h, respectively). In the absence of milkweed, adults ceased oviposition (mean 0.9 eggs in 48 h), but resumed oviposition when the dog‐strangler vine was replaced with milkweed (mean 99.1 eggs in 48 h). Given a choice between hosts over 24 h, 92% of larvae moved to milkweed leaves and consumed 3.94 cm² of milkweed leaves compared to 2% of larvae that moved to dog‐strangler vine and consumed negligible amounts of leaf material (0.01 cm²). Without a choice, larvae on dog‐strangler vine never consumed more than mean 0.02 cm² larva^?1 in a 24‐h period, did not develop beyond the first instar, and died within 96 h. We obtained no data in support of an effect of the presence of dog‐strangler vine on monarch butterfly populations.     

Performance of Microplitis tuberculifer (Hymenoptera: Braconidae) parasitizing Mythimna separata (Lepidoptera: Noctuidae) in different larval instars

The solitary parasitoid Microplitis tuberculifer (Wesmael) is an important biological control agent of various lepidopteran pests in Asia. We examined the preference of M. tuberculifer for different instars of its common host, Mythimna separata (Walker), host instar effects on parasitoid development, and the consequences of parasitism in different stages for growth and consumption of host larvae. The wasp successfully parasitized the first four larval instars of M. separata, but not the fifth, which appeared to be behaviorally resistant. First and second instars were parasitized at higher rates compared to thirds and fourths in no-choice situations, ostensibly due to longer handling times for the latter, but second instars were most preferred in a choice test that presented all stages simultaneously. Although later instar hosts yielded heavier cocoons, the fastest parasitoid development was obtained in second instars. Lower sex ratios were obtained from first instars as females appeared to lay a smaller proportion of fertilized eggs in small hosts. Both weight gain and food consumption of parasitized larvae were reduced significantly within 24 h of parasitism, regardless of the stage parasitized, and final body weights were less than 10% those of unparasitized larvae. Thus, M. tuberculifer has good potential as a biological control agent of M. separata, successfully parasitizing the first four larval instars and dramatically reducing plant consumption by the host in all cases.     

Prey preference of predatory mite Amblyseius swirskii (Acari: Phytoseiidae) on Tetranychus urticae (Acari: Tetranychidae) and Bemisia tabaci (Hemiptera: Aleyrodidae)

Tetranychus urticae Koch (Acari: Tetranychidae) and Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) are major pests in greenhouse crops. Recently, Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) was shown to be an effective biological control agent of both pests. Therefore, the prey preference of A. swirskii was determined using immature stages of T. urticae and B. tabaci in three various treatments based on Manly's β preference index (β). These treatments consisted of immature stages of two prey species (egg, first and second instar nymphs) with densities 12:12, 6:6 and 3:3, respectively, and with 13 replicates. After 24?h starvation, same-aged females of A. swirskii were added to the leaf discs. All experiments were done on bean leaf discs in Petri dishes (8?cm in diameter) in laboratory conditions with 25?±?2°C, 70?±?5% relative humidity and the photoperiod of 16L:8D hours. Comparing the preference indices using t-tests indicates a significant preference of the predator on eggs (t?=?10.80, df?=?24, P?t?=?8.17, df?=?24, P?T. urticae than B. tabaci. Our findings suggest that developmental stages of prey have effect on the prey selection by A. swirskii.     

Substratum preference of the caddisfly Helicopsyche borealis (Hagen) (Trichoptera: Helicopsychidae)

The position of Helicopsyche borealis (Hagen) (Trichoptera: Helicopsychidae) larvae on the substratum surface is dependent on the current regime but varies with larval size. All size classes of larvae chose significantly different positions on the substratum under high versus low current velocities. All size classes preferred exposed surfaces under low current velocities. Small larvae preferred the upper surfaces of substrata under low current velocities and were physically displaced under high current velocities. Larger larvae also occurred on upper surfaces, but were more evenly dispersed over all surfaces than smaller larvae, and tended to aggregate on down-stream faces of rocks during high flow.     

Observations on substrate preference of marine phytal harpacticoids (copepoda)

Field observations show that some marine macro-algae harbour large numbers of harpacticoid copepods while other species occupying similar zones of the shore harbour none or only small numbers. The possibility of active substrate selection of specific algae was investigated in Porcellidium dilatatum (Porcellidiidae) by providing it with a choice of chemical stimuli. P. dilatatum was significantly (P 0.05) attracted to Zonaria turneriana the alga it is primarily associated with in nature. The attractive property of the seaweed was reduced and destroyed by physico-chemical treatments. The nature of the attraction is presumed to lie in the interaction between the macrophytic substrate and the surface microbial film.     

Preference of Tilapia rendalli (Boulenger) for some species of aquatic plants

Preference of juvenile red-breasted bream, Tilapia rendalli (Boulenger), for the macrophytes Ceratophyllum demersum L., Lagarosiphon ilicifolius (Oberm), Najas pectinata (Magnus) and Valisneria aethiopica (Frenzl) was determined. Fish were offered a mixture of the four macrophytes in equal quantities to determine selection. Preference was shown for V. aethiopica , whilst C. demersum was least selected. This preference order was checked by examination of stomach contents of fish from the same population in the wild and the differences are discussed.     

Ecological aspects of the external morphology and functionality of the psychomyiid female ovipositor (Insecta,Trichoptera)

Females of most psychomyiid species bear an elongated ovipositor enabling them to oviposit their eggs into grooves and cavities in different kinds of substrates in freshwaters. Although the preference of psychomyiid species for oviposition into distinct substrates and the subsequent larval life performance in aquatic habitats is already known, the mode of oviposition and the functional morphology of the elongated ovipositor have not been described until now. In this study we present SEM photographs of some psychomyiid species with female ovipositors of different lengths and shapes, explaining their preference for oviposition into distinct substrates. Additionally, we discuss some ecological aspects of the ovipositor shapes and the mode of egg laying for psychomyiids. The female ovipositor consists of two body segments, with an elongated IXth and a distinctly shorter Xth segment, which is flexible and can be pushed up dorsally when releasing the eggs. On the basis of SEM photographs, we suppose that the opening of the channel through which the eggs were released is located ventrally near the ovipositor tip. The ovipositor itself is characterised by a ventral cleft reaching from the gonoporus of segment IX to the tip of the last segment X. We stored adult females abdomina overnight in different aqueous dilutions of ethanol leading to different stages of swelling of the ovipositors (grade of swelling in distilled water >30% ethanol >70% ethanol). Some internal membrane-like structures, normally infolded into the ovipositor, became visible by the swelling of the ovipositor. We discuss the possible rearrangement of the organisation of segment IX resulting in the development of an ovipositor on the basis of SEM photographs of the differently swollen ovipositors.