Resistance of wild rices, Oryza spp., to the brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae)

Of the 128 wild rices screened, 83 accessions were resistant to the brown planthopper Nilaparvata lugens (Stål). Resistant accessions were non-preferred and significantly more individuals settled on susceptible TN1 plants than on resistant ones. The quantity of food ingested and assimilated by N. lugens on resistant accessions was less than on susceptible TN1. N. lugens caged on resistant accessions had slow nymphal development, reduced longevity and low fecundity. Two wild rice species, Oryza officinalis and O. punctata, reduced the percentage hatchability of N. lugens eggs. A significant reduction in population growth was observed on resistant accessions compared with susceptible TN1.     

Feeding behaviour of whitebacked planthopper, Sogatella furcifera (Horvath), on resistant and susceptible rice varieties

Feeding behaviour of the whitebacked planthopper Sogatella furcifera (Horvath) was studied on 30-, 45- and 60-day-old plants of seven resistant varieties and one susceptible variety of rice. The preference or otherwise of the hoppers to different varieties was studied in terms of the feeding marks made and the amount of honeydew excreted. The insect made more feeding marks and excreted less honeydew on resistant varieties than on the susceptible TN 1. The number of feeding marks increased with the increase in the plant age of varieties, while the honeydew excretion decreased.     

Bph36介导的抗性机制及相关信号通路的研究

褐飞虱（Nilaparvata lugens Stål., BPH）是水稻最主要的害虫之一,给水稻生产造成严重的危害。携带不同抗性基因的抗褐飞虱水稻材料抗性机制不同,挖掘普通野生稻抗褐飞虱基因并研究其介导的抗性机制及相关信号通路对水稻育种具有重要的意义。本研究基于课题组前期从广西普通野生稻‘W2183'挖掘出的位于4号染色体InDel标记S13和X48之间38 kb处新基因Bph36,以‘9311'和‘抗蚊青占'为感性对照,05RBPH16和NIL-Bph36为抗性对照,通过褐飞虱宿主选择性、蜜露量测定、褐飞虱存活率及褐飞虱生长速率等方法分析Bph36介导的抗褐飞虱机制;同时,以‘抗蚊青占'为感性对照,NIL-Bph36为抗性对照,通过qRT-PCR分析植物防御昆虫侵害的三大信号途径：水杨酸、茉莉酸和乙烯相关基因表达量的差异。抗性机制研究结果表明：褐飞虱在抗性材料植株上的虫口密度显著低于感性材料植株,抗性材料上的褐飞虱存活率、群体生长率及取食后排泄的蜜露量均比感性对照显著降低。Bph36介导的抗性机制是寄主抗生性和害虫趋避性相互作用的结果。qRT-PCR结果表明：褐飞虱取食后,各个时间段抗性材料NIL-Bph36植株中水杨酸合成相关基因EDS1、PAD4、PAL和水杨酸途径病程相关蛋白基因PR10的表达量显著高于感性材料‘抗蚊青占'植株中的表达量;抗性材料NIL-Bph36植株中,茉莉酸合成基因LOX2和茉莉酸积累基因AOS2的表达量比褐飞虱取食前显著提升,但是比同时段感性材料植株中表达量显著降低;褐飞虱取食后,抗、感性材料植株中乙烯信号途径基因EIN2的表达量都受到抑制,基因ACO3表达量都提高,但2种材料间的差异不显著。茉莉酸途径和乙烯途径参与了NIL-Bph36植株抗褐飞虱的基础防御反应,但Bph36激活的抗性不是茉莉酸和乙烯依赖的信号防御途径而是激活水杨酸依赖的系统获得性抗性。研究结果为进一步研究Bph36与其他抗性基因聚合,培育兼有多种抗性机制和防御信号途径的优良品种奠定基础。     

Effect of host plant resistance and insecticide on brown planthopper Nilaparvata lugens (Stål) and predator population development in the Mekong Delta, Vietnam

Crop yield and populations of brown planthopper Nilaparvata lugens (Stål), whitebacked planthopper Sogatella furcifera (Horvath) (Homoptera: Delphacidae), green leafhopper Nephotettix spp. (Homoptera: Cicadellidae), and hemipteran and spider predators were monitored on rice varieties susceptible, moderately resistant, and highly resistant to N. lugens, under insecticide-treated and insecticide-free conditions. Nilaparvata lugens outbreaks and hopperburned plants were observed only in plots of the insecticide-treated susceptible varieties. In insecticide-free plots, the yield of the susceptible variety was lower than those of resistant varieties in only one of four seasons. In plots of a moderately resistant and a highly resistant variety, populations of N. lugens, S. furcifera, Nephotettix spp., and predators were generally similar, and yields did not differ, under both insecticide-treated and insecticide-free conditions. In insecticide-free plots, predator-N. lugens ratios were generally higher on resistant varieties than susceptible varieties. Two conclusions can'be drawn from our results relevant to the question of what levels of N. lugens host plant resistance are appropriate for farmers who do not overuse insecticides. First, susceptible varieties will not necessarily be damaged by N. lugens, even when N. lugens outbreaks occur in adjacent plots. Second, moderate and high levels of N. lugens resistance do not appear to be incompatible with biological control of N. lugens or other homopteran pests.     

Responses of the alien leaf miners Liriomyza trifolii and Liriomyza huidobrensis (Diptera: Agromyzidae) to some pesticides scheduled for their control in the UK

Baseline responses to a range of pesticides scheduled for the statutory eradication of outbreaks of Liriomyza trifolii, a leaf miner alien to the UK, were established using a topical application bioassay against a susceptible laboratory population. Using the same technique the responses of outbreak populations of L. trifolii, and also the related species L. huidobrensis, have been investigated. Field populations of L. trifolii showed resistance to the pyrethroids tested but no evidence of resistance to organophosphates was found. There was some evidence of resistance to gamma-HCH. L. huidobrensis showed a response to pyrethroids similar to that of resistant L. trifolii, and levels of tolerance to organophosphates approximately eight times that of susceptible L. trifolii. The response to gamma-HCH was similar to that of susceptible L. trifolii.     

Impact of varietal resistance in rice and predation on the mortality of Sogatella furcifera (Horváth) (Homoptera: Delphacidae)

Highly resistant, resistant and susceptible rice cultivars were tested in the greenhouse to determine their effect on Sogatella furcifera (Horváth) populations. The highly resistant cultivar IR2035-117-3, with resistance genes Wbph 1 and Wbph 2, caused the highest S. furcifera mortality. When the effects of varietal resistance and predation were combined the increase in mortality due to predators was additive. The spider Lycosa pseudoannulata Boes. et Str., mirid bug Cytorhinus lividipennis Reuter, ladybird beetle Harmonia octomaculata (F.) and rove beetle Paederus fuscipes Curt. were effective predators of S. furcifera and generally caused 30% mortality on the various cultivars. Results indicate that the integration of varietal resistance and predation would provide effective control of S. furcifera populations under field conditions.     

白背飞虱在抗感稻株上分泌蜜露的氨基酸成分分析

白背飞虱吸食水稻植株的韧皮部,影响其正常生长。近年来,由此而引起的水稻产量损失愈加明显。推广种植抗虫品种有效地阻止了飞虱在其上取食与建立种群,在防治此虫中发挥了十分重要的作用。水稻抗虫品种对白背飞虱产生的不良影响是多方面的。为了探索稻株韧皮部内营养成分对飞虱的影响,我们采用间接的方法分析了飞虱取食抗感稻株后分泌的蜜露中氨基酸的成分与含量。1 材料与方法1.1 蜜露的收集测定蜜露中游离氯基酸总量时选用的抗白背飞虱     

Resistance of Oryza spp. to thrips, Stenchaetothrips biformis (Bagnall) (Thysanoptera: Thripidae)

A method to evaluate rice cultivars for resistance to Stenchaetothrips biformis (Bagnall) in the greenhouse was developed. Eleven traditional cultivars of Oryza sativa and 12 wild rices were selected for resistance. Studies on the mechanisms of resistance indicated that resistant cultivars were non-preferred for feeding and oviposition. Larval survival was lower and adult life shorter on resistant compared with susceptible cultivars. Resistant cultivars had an adverse effect on fecundity and oviposition rate which resulted in a low population growth. Plant injury on susceptible cultivars reduced plant weight and height.     

Field study of the interaction between Orobanche crenata Forsk. and some new lines of Vicia faba L. in Egypt

In Egypt, some newly derived lines of faba bean (Vicia faba L.) as well as Giza 402, all of which had shown a certain resistance against the parasitic weed Orobanche crenata Forsk., were tested in the field. For reasons of comparison, the susceptible cultivars Giza 3 and Reina Blanca were included in this test. Faba bean plants and Orobanche attachments were regularly harvested and examined. The susceptible cultivars completely collapsed before the end of the growing season, whereas others, particularly line 402/294, remained alive until pod formation was completed. It appeared that fewer Orobanche spikes emerged on the new lines and Giza 402. Evidence is given that this was not due to avoidance mechanisms, such as smaller root mass, a deeper root system or lack of germination stimulants. Numbers of Orobanche attachments per unit of lateral root length were found to be low. Hence, it could be concluded that these lines are partially resistant; this resistance must be due to some defence mechanism in their roots. The few Orobanche plants attached grew very fast so that final Orobanche dry weight was similar in resistant and susceptible host plants. Further experiments, including broomrape-free controls, are required to study whether some tolerance mechanism might be involved.     

Red-winged blackbird (Agelaius phoeniceus L). feeding response to oil and anthocyanin levels in sunflower meal

Bird damage to sunflowers might be reduced by the development of resistant cultivars. Neagra de Cluj may be one such cultivar, with high levels of anthocyanin (a possibly aversive flavour) in achene hulls, but low oil yield. Four experiments were designed to assess the importance of oil content and anthocyanin concentration in feeding preferences expressed by red-winged blackbirds (Agelaius phoeniceus L.). Differences in oil concentration of 15% (w/w) were reliably discriminated in two-choice tests: higher concentrations were preferred. Conversely, all anthocyanin concentrations (0·5, 1·0, 2·5 and 5·0% [w/w]) were avoided, and two-choice tests suggested that higher concentrations (2·5 and 5·0%) were relatively more aversive. Both anthocyanin concentration and oil content could influence Neagra de Cluj resistance to bird depredation. Of these two characteristics, oil may be relatively more important.     

若干粳稻品种（系）抗褐稻虱特征评价

 就一些粳稻抗性品种对褐稻虱(BPH)Nilaparvata lueens抗性进行了评价，水稻品种秀水48作感性品种对照。结果表明：1)褐稻虱在感性品种上分泌的蜜露面积显著地大于抗性品种；饲养在不同品种上褐稻虱一生产卵量(粒／♀)： 秀水48为316．2，秀水620为191，嘉23为165.2，IR64为87.5；不同品种上褐稻虱若虫的存活率：秀水48为100%，秀水620为44%，嘉23为28.22%；相对取食量与抗性等级、田间累计虫量、若虫存活率及产卵量呈正相关。2)不同抗性品种上褐稻虱的种群增长率，秀水48为0.1221，秀水620为0.088，嘉23-2为0.083．3) 供试品种上逻辑斯蒂模型的K值,秀水48为81.58．秀水620为30.54。4)本试验各品种对褐稻虱的内禀控制率(%)秀水48为0，秀水620为78.79，嘉23为8494，IR64为0.8632。5)各品种对褐稻虱田间控制率（%）秀水48为0，秀水620为77.23，嘉23-2为76.68。     

Control of Bromus species in winter barley in England using EPTC

EPTC was tested in glasshouse and field experiments for its potential as a herbicide to control Bromus species in winter cereals. Bromus hordeaceus, Bromus commutatus, Bromus pectinatus and Bromus sterilis were all selectively controlled in barley by EPTC. Winter wheat was found to be susceptible but winter barley tolerated doses up to 2·0 kg a.i./ha. The barley cultivar Sonja was more resistant than both Athene and Maris Otter. In the first field trial, 1·0 kg a.i./ha EPTC reduced B. sterilis plant numbers by 75% giving a barley yield increase of 2·84 t/ha. In the following year 2·0 kg a.i./ha reduced B. sterilis numbers by 54% and increased yield by 1·75 t/ha.     

Development and growth of two Lesquerella species grown under different temperatures during the reproductive period

The genus Lesquerella is a promising source of hydroxy fatty acids (HFA). Several species such as Lesquerella fendleri and Lesquerella mendocina are candidate crops for arid and semi-arid cropping systems. Several reports are available on the environmental effects on growth and yield in Lesquerella, but information on the effect of temperature on plant growth and development specifically during the reproductive period in Lesquerella is limited. The objective of this work was to determine the effect of two contrasting thermal regimes after flowering on time to maturity, plant growth and biomass allocation to the different organs in L. fendleri and L. mendocina. A greenhouse experiment was conducted with plants grown at a range of 11–23 °C during the vegetative phase. After this stage, 50% of the plants of each species remained under the same temperature regime until maturity, whereas the other 50% was transferred to another module subjected to a range of 17–31 °C until maturity. The duration of the reproductive phase was reduced by 23 days in plants of both species in the 17–31 °C treatment compared to those at 11–23 °C, although no differences were observed when the length of the reproductive phase was measured in thermal-time units. Total plant biomass for both species was 20% greater in the 11–23 °C treatment. In L. fendleri, this increment occurred due to more vegetative shoot biomass, whereas in L. mendocina it was associated with greater reproductive and root biomass. No changes in biomass allocation were produced by temperature in L. fendleri, while in L. mendocina the lower temperature regime increased allocation to the reproductive organs, at the expense of a lower allocation to vegetative shoot. These results could be used to predict the specific temperature effects after flowering on yield under field conditions, and suggest that L. mendocina might be a promising perennial alternative for cooler sites.     

Resistance to the legume pod borer, Maruca vitrata Fabricius, and the probable modalities involved in wild Vigna

A large number of accessions belonging to selected wild Vigna species namely V. unguiculata subspecies dekindtiana, V. oblongifolia, and V. vexillata were evaluated using choice (DCAT) and no-choice (NCFT) laboratory feeding bioassays to determine their resistance to the pod borer, Maruca vitrata Fabricius. The most resistant accessions belonged to V. vexillata, followed by those from V. oblongifolia, with a few outstanding exceptions from V. unguiculata. Even though the latter were the least resistant, they provided the greatest variability among the tested accessions. In the DCAT, the cultivated cowpea line, IT84S-2246, which was used as the susceptible control was always preferred for feeding by the larvae (feeding index [FI] of 1.10–2.60) than the V. unguiculata accessions (FI ranged from 0–0.52). Against the resistant control (itself belonging to V. vexillata), only a few accessions were less preferred, most of these being either V. vexillata or V. oblongifolia. Larvae lost weight on the most resistant from all three species, because they either did not feed, or fed very little. Weight gain was positively correlated with seed damage (r = 0.82, P < 0.01) and the amount of frass produced (r = 0.91, P < 0.01). Seed damage was also positively correlated with the amount of frass produced (r = 0.64, P < 0.05). On the basis of these results, we believe that both antibiosis (post-ingestive effects) and antixenosis (deterrence to boring into the pods to feed) modalities of resistance are involved. The results are discussed further in relation to the origin, domestication and use of these accessions in cowpea improvement.     

Clonal performance of perennial Oryza sativa/O. rufipogon selections and their combining ability with O. sativa cultivars for survival, stolon production and yield

In Southeast Asia, upland rice (Oryza sativa) is an annual crop typically grown for subsistence on hilly lands that are at risk for soil erosion. If perennial cultivars of upland rice were developed, they would provide farmers with an inexpensive tool to produce a preferred food while conserving soil. O. rufipogon, the undomesticated progenitor of O. sativa, includes perennial and stoloniferous forms. To evaluate the feasibility of developing perennial cultivars by combining genes of O. sativa and O. rufipogon, four trials were conducted in an upland field at IRRI: O. sativa/O. rufipogon F₁ clone and cutting height trial, F₂ family trial, and two O. sativa/stoloniferous-selection factorial mating design trials. Plants were established at the beginning of the rainy season, then subjected to a 6-month dry season and evaluated for survival after 1 year. Of the 2101 cultivar control plants, only three IR47686-1-4-B individuals survived and none produced stolons. The 18 F₁ clones, which were selected from previous trials with less drought stress, ranged in survival from 4.4 to 91.4%. Cutting height at harvest did not affect survival. Survival among the F₂ families ranged from 9.4 to 31.9%. Segregation for stolon presence did not differ from a 3:1 ratio for five of the six F₂ families, suggesting the effect of a single dominant gene. Average yields per plant for the F₂ families were 1/3 to 1/9 of yields for the cultivars. However, by crossing the F₁s to cultivars, yield potential was almost fully recovered. For the full-sib families of the factorial trials, survival ranged from 0.0 to 48.6%. Azucena and IR47686-1-4-B, both japonica cultivars, exhibited greater general combining ability for survival relative to the six other cultivar parents. Thus, the process of developing perennial cultivars of rice should include screening annual cultivars to identify those with the best combining ability for survival. To develop cultivars of perennial upland rice, drought avoidance and/or tolerance from annual upland cultivars must be combined with the capacity for perennial growth from wild perennial species. The frequency of stolonifereous testcross progeny was lower than expected and was affected by the O. sativa parent. Thus, additional genes likely affected stolon penetrance and expression. Analyses of covariance indicated that stolons improved the likelihood of survival for progenies of the factorial trials but the effect was small (b < 0.1), and that yield (g/plant) had a small negative effect on percent survival (b = −0.13 to −0.32). This study demonstrated that it was possible to introgress genes for perennial growth from wild O. rufipogon accessions into domesticated O. sativa. Additionally, strategies for developing perennial cultivars of upland rice were improved.     

Resistance of the rice variety Utri Rajapan to ragged stunt and tungro viruses

Utri Rajapan, a rice variety tolerant to the brown planthopper, Nilaparvata lugens, was resistant to rice ragged stunt virus transmitted by N. lugens and to rice tungro virus transmitted by the green leafhopper, Nephottetix virescens. Although some Utri Rajapan plants became infected with tungro virus, symptoms were mild and disappeared as the plant matured. Of the two tungro-associated viruses, only rice tungro bacilliform virus was present in Utri Rajapan. The infected plants thus did not serve as a source of inoculum for transmission to healthy plants, as rice tungro spherical virus must also be present for transmission to occur.     

不同小麦品种(系)对禾谷孢囊线虫的抗性评价

为了筛选抗禾谷孢囊线虫(Heterodera avenae)的小麦资源,以禾谷孢囊线虫保定群体为试虫,采用室内接种方法测试了41份来自CIMMYT的小麦品种(系)的抗病性;分别采用室内接种法和田间病圃法测试了27份国内冬小麦品种和1份饲用小麦品种的抗病性。结果表明,在41份CIMMYT小麦品种(系)中,2个属高抗,7个属中抗,其他均属感病。所有参试的国内小麦品种在室内和田间测定中均表现为高感。比较三种不同小麦品种抗孢囊线虫鉴定方法,室内接种鉴定比田间病圃鉴定发病严重,且简便易行,鉴定结果更可靠。     

水稻抗纹枯病育种成效的初步评价

以广东省和江苏省里下河农科所新近育成的部分籼稻品种（系）、扬州大学农学院的研究组以不同抗源杂交后代向抗感两个极端选育的9份籼稻品系以及另一组合向抗病方向选育的5份籼稻品系为材料,设置抗感病对照,进行田间纹枯病菌接种试验。结果表明品种间对纹枯病的抗性存在极显著差异;聚类分析将参试材料按抗性水平高低聚为6类：高度感病、感病、中等感病、中等抗病、抗病和更高水平抗病。广东品种在6种类型中均有分布,但属于抗和更抗类型的品种只有3个。扬州大学农学院对抗×抗杂交向抗感两个极端选育的品系在病级的中间类型中几乎没有分布;而向抗病方向选育的品系则仅分布于中抗至抗病的范围内,且属于抗的品种数占此类品种的60%。江苏省里下河农科所近些年育成的几个品种则只分布于后4类之中,且最高水平抗性的3个品种中,其品种占2/3。表明水稻对纹枯病的抗性是可遗传的性状,对抗性的选择有效。     

Antifungal modes of action of metalaxyl, cyprofuram, benalaxyl and oxadixyl in phenylamide-sensitive and phenylamide-resistant strains of Phytophthora megasperma f. sp. medicaginis and Phytophthora infestans

The activity of the phenylamide fungicides metalaxyl, cyprofuram, benalaxyl and oxadixyl against phenylamide-sensitive and phenylamide-resistant strains of Phytophthora megasperma f. sp. medicaginis and Phytophthora infestans has been compared in several tests. Metalaxyl showed the highest activity amongst the four fungicides against mycelial growth of sensitive strains on agar media. Benalaxyl and cyprofuram showed the highest activity against resistant strains. RNA synthesis of sensitive strains, measured as [³H]uridine incorporation, was inhibited by about 80% (P. megasperma) and by about 40% (P. infestans) by all phenylamides at concentrations of 1 μg/ml. At higher concentrations inhibition remained at this level, indicating that only part of the RNA synthesis was inhibited. RNA synthesis of resistant strains was completely insensitive to metalaxyl and oxadixyl at concentrations as high as 200 μg/ml. Cyprofuram, however, at concentrations above 1 μg/ml (P. megasperma) and 10 μg/ml (P. infestans) was inhibitory and at 200 μg/ml this compound almost completely inhibited the phenylamide-sensitive part of the RNA synthesis of both strains. In contrast to the other phenylamides, benalaxyl affected [³H]uridine uptake into mycelium at concentrations higher than 10 μg/ml, and at 100 μg/ml inhibition of uptake was almost total with both sensitive and resistant strains of both Phytophthora species. Inhibition of [³H]uridine uptake obviously is a feature of a second mechanism of action of benalaxyl. Endogenous RNA polymerase activity of isolated nuclei from sensitive strains of P. megasperma was inhibited at phenylamide concentrations as low as 0·1 μg/ml whereas that from resistant strains was not affected at concentrations as high as 100 μg/ml. Similarly, endogenous nuclear RNA polymerase activity of sensitive P. infestans strains appeared to be more sensitive to the phenylamides than that of resistant P. infestans strains. This suggests that resistance that developed in field strains of P. infestans has a basis similar to that of mutagen-induced resistance in laboratory strains of P. megasperma. Tests of the fungicidal activity of the phenylamides determined in a lucerne seedling assay (P. megasperma) and a detached potato leaf assay (P. infestans) clearly differentiated between sensitive and resistant strains. Resistance levels to cyprofuram and benalaxyl were as high as those to metalaxyl and oxadixyl, indicating that the additional effect of a second mechanism of action of benalaxyl and the property of cyprofuram to inhibit RNA synthesis of resistant strains at higher concentrations are of limited practical importance for counteracting phenylamide resistance.     

部分国内外小麦种质资源对燕麦孢囊线虫的抗病性

燕麦孢囊线虫是小麦生产上的重要病原线虫。为筛选抗燕麦孢囊线虫的小麦种质资源,采用室内接种方法测试了104个国外小麦品种（系）和37个国内小麦品种对燕麦孢囊线虫的抗病性,并利用不同抗性评价标准在自然病田对37个国内小麦品种的抗病性进行了评价。室内接种试验表明,104份国外小麦品种（系）中有高抗品种（系）14个,中抗品种（系）12个,中感品种（系）27个,其他均属高感,37个国内参试品种均属感病品种。自然病田鉴定结果表明,采用不同的评价标准对37个国内品种的评价结果具有较大差异。依据Andersen等的评价标准,37个小麦品种中有7个品种表现感病,30个品种表现抗病,与室内接种测试结果差异较大;依据Ireholm的标准,仅良星66表现抗病,其他品种均表现感病,与室内测试结果接近;依据Soriano等的标准,37个品种均表现感病,与室内测试结果相同。建议在筛选抗孢囊线虫小麦资源时首先采用Andersen等的标准进行初筛,然后利用Soriano等的标准进行田间评价。