禾谷镰孢菌对多菌灵的敏感性基线及抗药性菌株生物学性质研究

 引起小麦赤霉病的禾谷镰孢菌(Fusarium graminearum)在华东地区对多菌灵已出现了高水平抗药性。本文报道了F.graminearum对多菌灵的敏感性基线及其抗药性菌株生物学特性。离体条件下多菌灵对100个野生敏感型菌株的平均EC₅₀和MIC值分别为0.5748±0.0133 μg/ml和 < 1.4μg/ml。而对50个抗药性菌株的平均EC₅₀和MIC值则分别为9.2375μg/ml和 > 100 μg/ml。在麦穗上多菌灵对50个敏感菌株和抗药性菌株防效的平均EC₅₀分别为282.6 μg/ml和 > 2 000μg/ml。从田间获得的抗多菌灵菌株对苯菌灵、噻菌灵、甲基托布津表现交互抗药性,但不同于室内突变菌株,对乙霉威不表现负交互抗药性。抗药性菌株的无性和有性繁殖后代以及在无药培养基上菌丝体转代培养后,抗药水平保持不变。抗药性菌株的菌丝生长速率、产孢能力及致病力等与敏感菌株相比没有差异。     

蚜虫性信息素研究进展

本文对蚜虫性信息素成分的分离与鉴定、蚜虫性信息素对蚜虫及其天敌行为调节作用等方面的研究现状作了概述。     

Biological characteristics of maize dwarf mosaic potyvirus from Spain

Two isolates of maize dwarf mosaic virus (MDMV-Sp and MDMV-Spl) obtained from maize in the northeast of Spain were studied. Both isolates induced similar reactions on 6 sorghum cultivars, johnsongrass and oat (cv. Clintland), with the exception of MDMV-Sp which produced a different reaction on one sorghum cultivar. Thirty-three grass species were tested as possible hosts (16 previously untested) and 18 were found to be susceptible. Among those, eight were previously unidentified hosts for MDMV:Aegilops ovata, A. ventricosa, Avena barbata, Bromus alopecurus, B. diandrus, B. fasciculatus, Echinaria capitata andLolium rigidum. Both isolates were transmitted from maize to maize nonpersistently byRhopalosiphum maidis, R. padi, Schizaphis graminum andSitobium avenae. The virus was not seed-transmitted in Mo17 and B73 maize inbred lines. Pinwheels, scrolls and short curved laminated aggregates were observed in the cytoplasm of maize cells infected by MDMV-Sp or MDMV-Sp1. In addition, laminated aggregates were observed in cells infected by MDMV-Sp1.     

条锈菌侵染早期小麦叶片RNA和rRNA的合成

 采用示踪方法研究了条锈菌侵染早期小麦叶片的RNA和rRNA合成。结果表21h期间,表现不亲和性反应的叶片总RNA合成有所增加,而亲和性反应寄主叶片则低rRNA合成未受侵染影响。在接种后39~45h期间,只有呈亲和性反应的寄主叶片RNA和大幅度增加。对rRNA各组分合成的测定表明条锈菌侵染所影响的只是大分子量rRNA,胞质和叶绿体rRNA的合成也存在差别。文中讨论了上述变化的病理学意义。     

油菜品种抗蚜性多目标模糊综合决策

作者采用模糊统计回归法，建立了油菜品种的自然感蚜量、蚜虫在品种上的“累积存活率”，平均发育历期、平均产仔量、内禀增长率及品种耐害性、干扰效应等抗性指的模糊隶属函数，建立了品种抗蚜性的模糊综合决策模型。结果表明，１２个品种抗性强弱为：红叶芥＞咸阳７４－１＞甘油５号＞８８６３１＞７２１１＞７５－１＞波力木耳＞８８６３８＞德国１５选株＞华油９号＞秦油３号＞秦油２号。同时作者提出的一套衡量品种抗性的指禁     

Impacts of atmospheric CO<Subscript>2</Subscript> concentrations and soil water on the population dynamics,fecundity and development of the bird cherry-oat aphid<Emphasis Type="Italic">Rhopalosiphum padi</Emphasis>

The impacts of elevated CO₂ and soil water on the population dynamics, adult fecundity and nymphal period of the bird cherry-oat aphidRhopalsiphum padi (Linnaeus) were evaluated in three experiments: (i)Combined effects of CO ₂ and soil water on aphid populations. Spring wheat was grown in pots at three CO₂ concentrations (350, 550 and 700 ppm) and three soil water levels (40%, 60% and 80% of field water capacity, FWC) in field open-top chambers (OTC) and infested with the bird cherry-oat aphid. Aphid population dynamics were recorded throughout the growing season; at the same time, adult fecundity and duration of the nymphal period were recorded. Chemical composition of spring wheat leaves was also analyzed. (ii)Indirect effects of CO ₂ concentrations and soil water on aphid adult fecundity and nymphal period. The experiment was conducted with the leaf discs method in the laboratory. Aphids were reared on leaf discs excised from the treated wheat in OTC with different CO₂ and soil water levels. (iii)Direct effects of CO ₂ concentrations on aphid adult fecundity and nymphal period. Aphids were reared on leaf discs excised from the wheat grown under natural conditions. The experiment was conducted with the leaf disc method in OTC with the three CO₂ concentrations. It was found that the direct effect of CO₂ concentration on aphid population parameters was minor. CO₂ and soil water affected aphid population indirectly through their effects on wheat characteristics. The aphid population under 550 ppm CO₂ was far larger than the one under 350 ppm CO₂, whereas the population under 700 ppm CO₂ was slightly higher than that under 550 ppm CO₂. The largest aphid population was obtained with the 60% soil water treatment, regardless of CO₂ treatment. The effects of CO₂ concentration on aphid population were, however, not significantly correlated with soil water level. Adult fecundity increased with CO₂ concentration, the highest fecundity being achieved under 60% FWC treatments. The nymphal period was not affected by CO₂ concentration. The shortest period occurred under 60% FWC. Atmospheric CO₂ and soil water had significant effects on the chemical composition of the wheat leaves. Aphid population size was positively correlated with leaf water content, concentrations of soluble proteins, soluble carbohydrates and starch, and negatively correlated with DIMBOA and tannins concentrations. http://www.phytoparasitica.org posting Oct. 20, 2003.     

Assessment of Transmission Ability of Barley Yellow Dwarf Virus-PAV Isolates by Different Populations of Rhopalosiphum padi and Sitobion avenae

Populations of two aphid species from different geographic regions of Morocco were tested for their ability to transmit five barley yellow dwarf virus-PAV (BYDV-PAV) type isolates using Clintland 64 oat as the test plant. Transmission efficiencies were determined for 10 sub-populations of Rhopalosiphum padi and 12 sub-populations of Sitobion avenae. After a short acquisition access period (AAP) of 4h, all populations transmitted the virus but with different efficiencies. R. padi (Rp-S) and S. avenae (Sa-S) collected in the Settat region were the most efficient vectors, with transmission rates of 38% and 27%, respectively. R. padi (Rp-C) collected at Chaouen and S. avenae (Sa-B) at Berkane, were poor transmitters with respective vectoring abilities of 20% and 16%. These four sub-populations were chosen to study the acquisition of BYDV-PAV and the retention of virus within aphids in more detail. The transmission after two AAPs of 4h and 48h were compared. Starved aphids given a 4h AAP had significantly higher transmission efficiencies than non-starved aphids. However, after a 48h AAP, no difference was observed in the transmission between starved and non-starved aphids. Intraspecific variability was also detected by means of serial transfers of individual aphids after the given AAP. Following the first day of serial transfers, no differences were observed in transmission efficiency and virus titers for sub-populations within each species acquiring the virus during 48h, but there was significant variation when the virus was acquired in 4h. The levels of PAV antigen retained by aphids fed on healthy plants declined rapidly during the first day after acquisition, but remained fairly constant during the next 5–7 days depending on the length of the AAP. Virus antigen could be detected by ELISA in Rp-S and Sa-S for up to 11 days of serial transfer, but it was shown that aphids could retain and transmit BYDV-PAV for at least 3 weeks.     

七星瓢虫对两种麦蚜控制作用的模拟研究

应用二次回归旋转组合设计方法研究了七星瓢虫成虫、幼虫与两种麦蚜共存系统中瓢虫对麦长管蚜和禾谷缢管蚜的捕食量模型。结果表明七星瓢虫对两种麦蚜的捕食量随着瓢虫密度的增加而减少．随着该种麦蚜密度的增加而增加．且七星瓢虫无选择性。七星瓢虫不同个体间的干扰作用对其捕食麦长管蚜数量有显著影响,两种麦蚜数交互作用对七星瓢虫捕食禾谷缢管蚜数量影响显著。该模型可用来预测田间蚜虫的变化．指导麦田蚜虫防治。     

A Severe Hellenic CMV Tomato Isolate: Symptom Variability in Tobacco, Characterization and Discrimination of Variants

A severe strain of Cucumber mosaic virus (CMV) originating from an infected tomato plant (Gastouni-Olympia, Greece) was isolated in tobacco (Nicotiana tabacum cv. Xanthi nc), after three serial local lesion passages in Chenopodium quinoa and designated CMV-G. CMV-G induces yellow mosaic (YM) symptoms in tobacco. When CMV-G was passed mechanically through C. quinoa, phenotypic variants inducing YM or green mild mosaic (MM) in tobacco were isolated. Aphid transmission, from different hosts, appears to be an effective approach for separating MM variants of CMV-G from YM variants. In particular, aphid transmission from zucchini proved to be very efficient in selecting for MM variants. In contrast, aphids transmitted only YM variants from tomato plants. Molecular characterization of CMV-G and its progeny resulted in their classification in the CMV subgroup IB, free of satellite RNA, being the first discovery of the subgroup IB in Greece. In the Solanaceae family (tobacco, tomato, pepper) YM variants induced more severe symptoms than the MM variants. YM and MM phenotype was stable in tobacco for all seven passages tried using the obtained YM and MM variants. Cross-protection experiments showed that an isolated MM variant was able to protect tobacco plants against a challenge infection by a YM variant.