施氮对苜蓿根茎叶光合产物分配及抗蓟马的影响

为了探究施氮对苜蓿抗蓟马的影响, 本试验在大田网室盆栽条件下, 以‘甘农3号’和‘甘农9号’苜蓿品种为材料, 以牛角花齿蓟马Odontothrips loti为研究对象, 设4个施氮处理(N1, N2, N3, N4)和1个不施氮的对照, 评价不同施氮水平下苜蓿的受害程度, 并测定苜蓿根茎叶生物量和可溶性糖含量。结果表明:1)施氮后2个苜蓿品种的受害指数均升高; 受牛角花齿蓟马为害7 d后, 2个苜蓿品种的受害指数均在N2处理下最高, 分别比对照高39.93%和20.06%; 受害14 d后, ‘甘农3号’的受害指数在N3处理下最大, 比对照高28.51%, ‘甘农9号’的受害指数在N1处理下最大, 比对照高23.97%; 在同一施氮水平下, ‘甘农3号’的受害指数均明显高于‘甘农9号’。2)施氮后2个苜蓿品种根茎叶的生物量增加, 但叶茎比和根冠比降低, 生物量更多向茎秆中分配, 向叶片和根系中分配较少。3)苜蓿叶片中的可溶性糖含量随施氮量的增加而减少, 而茎秆和根系中的可溶性糖含量升高。施氮降低了苜蓿对牛角花齿蓟马的抗性, 促进了苜蓿根茎叶的生长, 但根冠比下降, 致使苜蓿的再生能力和耐虫性下降; 施氮后苜蓿叶片中的可溶性糖含量下降, 使叶片合成防御物质的碳源不足, 进而导致苜蓿对蓟马的抗性降低。     

刈割强度对不同根型苜蓿主要非结构性碳水化合物含量的影响

本研究以直根型‘陇东’紫花苜蓿、根蘖型‘甘农2号’杂花苜蓿和根茎型‘清水’紫花苜蓿为试验材料,设置4个刈割强度(距离上次刈割恢复生长分别为20、27、34、41 d),研究不同刈割强度对各根型苜蓿根、茎、叶的贮藏营养物质含量(可溶性糖、蔗糖、淀粉、还原性糖)的影响,为探明不同根型苜蓿刈割后翌年再生状况,为其合理有效利用提供理论依据。结果表明:6月份可溶性糖含量在叶中最高,还原性糖含量在茎中最高,淀粉和蔗糖含量在根中最高,其均值分别为5.75%、2.32%、3.16%、4.38%;9月份可溶性糖、还原性糖、淀粉、蔗糖含量均在根中最高,其均值分别为18.43%、2.57%、5.78%、14.12%。不同根型苜蓿在每27 d刈割强度下可溶性糖、淀粉、蔗糖含量高于其他处理,在每41 d刈割强度下还原性糖含量高于其他处理。根蘖型‘甘农2号’杂花苜蓿和根茎型‘清水’紫花苜蓿秋季根的贮藏营养物质含量接近并高于直根型‘陇东’紫花苜蓿,表明根蘖型、根茎型苜蓿抗寒越冬性较强。     

不同方法对14个苜蓿品种抗蚜评价分析

本试验研究了抗蚜株率、感蚜指数和改进的感蚜指数3种评价方法对14个苜蓿品种抗蚜评价的影响。结果表明:以抗蚜株率为标准,‘甘农9号’抗性最好;以感蚜指数为标准,‘阿尔冈金’抗性最好。而采用改进后的感蚜指数评价方法可将14个苜蓿品种分为7个等级,其中‘WL-319’为高感品种,‘巨能Ⅱ’为感虫品种,‘新牧4号’‘甘农5号’‘WL-354’‘WL-363’为低感品种,‘新牧1号’为中间品种,‘甘农9号’为低抗品种,‘MF4020’为中抗品种,‘中苜1号’‘WL-343’‘阿尔冈金’‘苜蓿王’‘SK3010’为高抗品种。改进后的感蚜指数评价方法符合“1±0.1”等差数列分级标准,使不同抗性级别符合正态分布,具有统计学意义。同时,该方法充分考虑了天敌对蚜虫发生量的影响,在生产实践中具有重要的推广应用价值。     

4个苜蓿品种对两种体色豌豆蚜的抗生性

在抗蚜鉴定的基础上,在室内20℃条件下,选用4个抗蚜性不同的苜蓿品种,测定了不同苜蓿品种上两种体色豌豆蚜的生物学参数。结果显示,两种体色豌豆蚜在‘金皇后’上的发育历期、净生殖率、平均世代周期差异显著(P0.05),绿色豌豆蚜若虫的发育历期长于红色型,而红色豌豆蚜的净生殖率、平均世代周期大于绿色型;在‘甘农5号’上两种色型豌豆蚜的内禀增长率、周限增长率、种群加倍时间差异显著(P0.05),绿色豌豆蚜的内禀增长率、周限增长率高于红色型,种群加倍时间低于红色型。以内禀增长率作为测定抗生性的指标,4个苜蓿品种对两种色型豌豆蚜的抗性表现不同,其中‘金皇后’对绿色豌豆蚜的抗性较高,‘甘农5号’对红色豌豆蚜的抗性较高,‘猎人河’对两种色型豌豆蚜的抗性均较低,4个苜蓿品种对绿色豌豆蚜抗性的大小顺序为‘金皇后’‘甘农5号’‘甘农3号’‘猎人河’,对红色豌豆蚜抗性大小依次为‘甘农5号’‘甘农3号’‘金皇后’‘猎人河’。     

不同苜蓿品种对镰孢菌的抗性鉴定

为探明苜蓿不同品种对能引起苜蓿根腐病的茄镰孢(Fusarium solani)、半裸镰孢(F. semitectum)、弯角镰孢(F. camptoceras)等3种镰孢菌的抗性差异,提供筛选抗耐病性材料的新来源,通过室内盆栽法,对30个苜蓿品种(系)进行了苗期抗病性鉴定,结果表明,各品种之间抗病性差异显著,其中‘德里兰德’、‘新疆大叶’、‘苜蓿王’对半裸镰孢表现为抗病,病情指数分别为18.11、19.93、19.96,占鉴定总数的10%;总体来看,‘猎人河’等7个品种表现耐病,病情指数为25.30～39.95,占鉴定总数的23.3%;‘甘农2号’等18个感病品种,病情指数为40.55～59.56,占鉴定品种总数的60.0%;‘德宝’等5个品种为高感,平均病情指数为61.7~68.6,占鉴定总品种数的16.7%,无免疫和抗病品种。     

四个苜蓿品种无性系大田抗蓟马性能评价

本研究选用室内筛选的4个不同抗性级别的苜蓿品种（HA 3、Ta、M8和Ja）的无性系,以大田苜蓿地牛角花齿蓟马为虫源,任其自然受害,以喷药小区为对照,于现蕾期测定分析各品种无性系的受害指数、虫量、农艺性状和产量损失率,结果表明,7月和8月,4个苜蓿品种无性系的受害指数的排列顺序均为HA 3＜Ta＜M8＜Ja,HA 3与Ja之间受害指数存在显著差异（p<0.05）;受害指数与虫口密度之间无相关性;各无性系受害株的株高、茎粗、节间长、叶面积及干重均显著低于对照（p<0.05）,但分枝数和节间数均显著高于对照（p<0.05）,其中HA 3的各农艺性状表现均优于其他苜蓿品种,产量损失率也最低。苜蓿对蓟马的抗性主要表现为耐害性,其中HA 3的耐害性最强。     

牛角花齿蓟马为害对紫花苜蓿生长及氮代谢的影响

为了明确牛角花齿蓟马为害对紫花苜蓿生长及氮代谢的影响,测定了不同牛角花齿蓟马虫口密度下抗、感蓟马苜蓿无性系R-1、I-1的受害指数、单株生物量及氮代谢的变化。结果表明：（1）随着牛角花齿蓟马虫口密度的增加,R-1、I-1无性系各接虫处理的受害指数均升高、单株生物量均下降,在相同牛角花齿蓟马虫口密度下,R-1无性系的受害指数及产量损失率均低于I-1无性系。（2）受牛角花齿蓟马为害后,R-1无性系各接虫处理硝酸还原酶活性上升后趋于稳定,硝态氮含量呈先上升后下降的趋势,游离氨基酸含量呈持续上升的趋势; I-1无性系各接虫处理的硝酸还原酶活性呈先上升后下降的趋势,硝态氮含量呈先下降后上升的趋势,游离氨基酸含量上升后趋于稳定或下降。结果说明：硝酸还原酶活性的升高是R-1无性系对蓟马诱导抗性的一种表现,而I-1无性系氮代谢失调是其感蓟马的主要原因之一,因此R-1无性系的适应能力强,受害较轻,对牛角花齿蓟马为害的抗性和补偿生长能力高于I-1无性系。     

西花蓟马为害对菜豆叶绿素及营养物质含量的影响

本文研究了西花蓟马不同虫口密度(0～40头/叶)为害菜豆叶片不同时间(2～8 d)后,对菜豆生理指标的影响.结果显示虫口密度的增加和为害时间的延长均能引起菜豆叶片内叶绿素、可溶性糖、可溶性蛋白质及游离氨基酸含量的变化.其中叶绿素含量随取食时间的延长和虫口密度的增加呈递减趋势.可溶性糖含量和可溶性蛋白的变化趋势相同,不同虫口密度处理下可溶性糖和可溶性蛋白的含量均低于对照,在相同处理时间下均随虫口密度的增加而降低,在同一虫口密度下均随取食时间的延长先下降,后升高,再下降.游离氨基酸的含量在为害前期(2～4 d)随虫口密度的增加而降低,为害后期(6～8 d)其含量在各虫口密度下没有显著差异.     

茶树叶片理化性质对茶蚜取食选择性的影响

为明确茶蚜Toxoptera aurantii Boyer de Fonscolombe寄主选择行为机理, 通过自由选择法研究有翅成蚜对7个茶树品种的取食选择性, 利用蚜量比值法对供试茶树品种进行抗性鉴定, 并进一步分析茶蚜取食选择性与茶树叶片物理性状及主要生化成分的相关性。结果表明, 有翅成蚜对7个茶树品种的取食选择性存在差异, 其中对‘黄金芽’的选择性最强, 而对‘黔茶1号’和‘黔茶10号’的选择性最弱。抗蚜性鉴定结果表明, 供试茶树品种中, ‘黔茶1号’‘黔茶10号’为抗虫品种; ‘福鼎大白茶’‘龙井43’‘黔茶8号’为中抗品种; ‘黔湄601’为感虫品种; ‘黄金芽’为高感品种。Pearson相关性分析显示, 茶蚜取食选择性与茶树叶片总厚度(r=-0.84)、下表皮厚度(r=-0.78)、栅栏组织厚度(r=-0.94)、咖啡碱含量(r=-0.91)、茶多酚含量(r=-0.94)呈显著负相关, 与气孔密度(r=0.93)、游离氨基酸含量(r=0.94)呈显著正相关, 而与海绵组织厚度(r=-0.27)、可溶性糖含量(r=0.75)无显著相关性。本研究可为我国抗蚜种质资源鉴选及利用、茶蚜的绿色防控提供理论依据。     

螺旋粉虱对不同甜椒品种的产卵选择性及与植物中化学物质的相互关系研究

［目的］ 明确螺旋粉虱对不同甜椒品种的产卵偏好性及其与甜椒体内化学物质含量的关系。［方法］ 采用非自由选择法测定了螺旋粉虱对不同甜椒品种的产卵偏好性,并测定不同甜椒品种体内单宁酸、总黄酮、可溶性糖、可溶性蛋白等化学物质含量,分析其与螺旋粉虱产卵选择的相关性。［结果］ 螺旋粉虱对‘古风7号’的选择性最强,产卵量显著高于‘特大型牟一号’、‘吉星’、‘京椒’、‘特大甜椒八号’等8个品种（α=0.05水平）,而与‘国禧205’、‘郑椒甜宝’、‘古风5号’等7个品种差异不显著。不同甜椒品种间的单宁酸含量、总黄酮含量、可溶性糖含量、可溶性蛋白含量存在显著差异。相关分析表明,螺旋粉虱对甜椒品种的选择性与单宁酸、总黄酮不相关,与可溶性蛋白呈负相关,与可溶性糖含量呈正相关。［结论］ 螺旋粉虱对不同甜椒品种的偏好性存在显著差异,这种差异与甜椒体内一些化学物质含量不同有关。     

Hymenopteran Parasitoids on Fruit-infesting Tephritidae (Diptera) in Latin America and the Southern United States: Diversity, Distribution, Taxonomic Status and their use in Fruit Fly Biological Control

We first discuss the diversity of fruit fly (Diptera: Tephritidae) parasitoids (Hymenoptera) of the Neotropics. Even though the emphasis is on Anastrepha parasitoids, we also review all the information available on parasitoids attacking flies in the genera Ceratitis, Rhagoletis, Rhagoletotrypeta, Toxotrypana and Zonosemata. We center our analysis in parasitoid guilds, parasitoid assemblage size and fly host profiles. We also discuss distribution patterns and the taxonomic status of all known Anastrepha parasitoids. We follow by providing a historical overview of biological control of pestiferous tephritids in Latin American and Florida (U.S.A.) and by analyzing the success or failure of classical and augmentative biological control programs implemented to date in these regions. We also discuss the lack of success of introductions of exotic fruit fly parasitoids in various Latin American countries. We finish by discussing the most pressing needs related to fruit fly biological control (classical, augmentative, and conservation modalities) in areas of the Neotropics where fruit fly populations severely restrict the development of commercial fruit growing. We also address the need for much more intensive research on the bioecology of native fruit fly parasitoids.     

Brief Guide for Authors

正Journal of Arid Land(JAL)is an international journal(ISSN 1674-6767;CN 65-1278/K)for the natural sciences,sponsored by the Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences and Science Press.It is published by Science Press and Springer-Verlag Berlin Heidelberg bimonthly.JAL publishes original,innovative,and integrative research from arid and semiarid regions,ad     

The parasitoid complex ofLiriomyza cicerina on chickpea (Cicer arietinum)

Liriomyza cicerina (Diptera: Agromyzidae) is an important pest on chickpea in Turkey. The objective of this study was to determine the parasitoids and rates of parasitism ofL. cicerina on chickpea (Cicer arietinum L.) during the 2005 and 2006 seasons in ?anl?urfa province, Turkey. Leaves with mines were sampled weekly and kept in the laboratory to observe and count emerging leafminer and parasitoid adults. Eight parasitoid species were collected: the braconidsOpius monilicornis Fischer andOpius tersus Foerster and the eulophidsDiaulinopsis arenaria (Erdös) andNeochrysocharis formosa (Westwood), which occurred in both the winter and summer seasons;Diglyphus crassinervis Erdös,Neochrysocharis ambitiosa Hansson,Neochrysocharis sericea (Erdös) andPediobius metallicus (Nees), which occurred only in the summer growing areas.Diaulinopsis arenaria was the predominant parasitoid with 4–7.7% parasitism rate whileN. ambitiosa andO. monilicornis were the second and third most predominant species. The results of these trials show that sinceDia. arenaria occurred throughout every season, it could potentially be used for control of the leafminerL. cicerina.     

Plant–herbivore asynchrony necessitates augmentative releases of the exotic beetle,Zygogramma bicolorata,to enhance the biological control of P arthenium hysterophorus

Systematic information on the quantitative impact of Z ygogramma bicolorata on the biology of P arthenium hysterophorus is crucial as the seeds of this weed continue to germinate from the accumulated soil seed bank throughout the year in the form of different germinating flushes, while the activity of the beetle ceases during winter as it enters diapause. Therefore, plant–herbivore interactions need to be explored to develop predictions of the overall impact of the introduced beetle on the weed. The findings revealed that defoliation by Z . bicolorata had a significant impact on the plant height, density and flower production in flushes F ₃, F ₄ and F ₅, but not in F ₁ and F ₂ that exhibited longer periodicity, profuse branching, a longer flowering period and maximum flower production and contributed mostly to the existing seed soil bank. Therefore, total depletion of the existing soil seed bank was not possible. Consequently, the effect of augmentative field releases of laboratory‐reared beetles was explored on F ₁ and F ₂ in February for three consecutive years (2011–2013). Before initiating the trial, random soil samples were taken from the plots that were assigned to the paired treatments (i.e. with the beetle and without the beetle [insecticide‐treated]) and it was found that the seed bank in those samples did not differ. The single release of Z . bicolorata adults at five per plant at the six‐leaf stage significantly reduced the soil seed bank, compared to without the biocontrol agent, irrespective of the flushes at the end of the season.     

Richtlinien der Verbände des ökologischen Landbaus zum Vorratsschutz

Zusammenfassung Verbände des ökologischen Landbaus wie z. B. Bioland, Gäa, Demeter; Naturland, Ernte für das Leben oder Bio Suisse beschränken ihre Mitglieder bei der Wahl von Vorratsschutzmaßnahmen. Vorrang besitzen Maßnahmen zur Vermeidung von Schädlingen gegenüber Bekämpfungsmaßnahmen. Fallen müssen zur Befallsüberwachung eingesetzt werden, um einen Befall durch Vorratsschädlinge frühzeitig zu erkennen. Diese Maßnahmen sollen den weitgehenden Verzicht auf chemisch-synthetische Mittel ermöglichen. In diesem Beitrag werden die Empfehlungen der Verbände mit den derzeit verfügbaren chemischen Mitteln für den Vorratsschutz abgeglichen. Erfahrung in der praktischen Umsetzung von physikalischen und biologischen Verfahren werden diskutiert und Defizite bei der Befallsüberwachung und Bekämpfung beschrieben.     

Development of protocols for detection of Colletotrichum acutatum and monitoring of strawberry anthracnose using real-time PCR

Real-time PCR (TaqMan®) assays were developed for the specific detection and discrimination of Colletotrichum spp., C. acutatum and C. gloeosporioides causing anthracnose in strawberry using the most divergent area of the internal transcribed spacers (ITS1 and ITS2) and 5·8S ribosomal RNA (rRNA) gene region. The specificity of the new assays was tested using DNA from six species of Colletotrichum and nine fungal species commonly found associated with strawberry material, and additionally by comparing the sequences with those from databases using a blast search. The sequences only showed identity with homologous sequences from the desired target organisms. The new assays were 10–100 times more sensitive than conventional PCR methods previously published for the diagnosis of strawberry anthracnose. When real-time PCR was compared with ELISA methods, PCR improved the sensitivity of the identification by obtaining positive results for samples of strawberry plant material that tested negative with ELISA. The development of C. acutatum was monitored using artificially infected strawberry crowns from two strawberry cultivars (Camarosa and Ventana) and a real-time PCR assay specific for this species between January and June 2006. The amount of C. acutatum detected using real-time PCR varied significantly by month ( P  < 0·001), but not by cultivar ( P  = 0·394). The new assays were shown to be useful tools for rapid detection and identification of these pathogens and to allow rapid and accurate assessment of the casual agents of anthracnose in strawberry.     

Effects of the saprophytic leaf mycoflora on growth and productivity of winter wheat

The effects of the saprophytic mycoflora and its interference with cereal aphids on growth and yield of winter and spring wheat was studied in field experiments in 1980, 1981 and 1982.Yields varied between 5000 and 8000 kg dry matter of kernels per ha. The effect of the saprophytic mycoflora on yield was determined in different treatments: A) no control measures against cereal aphids and saprophytic and necrotrophic fungi, B) no control of cereal aphids, control of saprophytic and necrotrophic fungi, C) control of cereal aphids and control of saprophytic and necrotrophic fungi, D) control of cereal aphids and stimulation of saprophytic mycoflora and E) control of cereal aphids, no control of saprophytic and necrotrophic fungi nor stimulation of saprophytic mycoflora.Considerable differences in top densities of saprophytic mycoflora (10 times as large in A and D as in B and C) were determined. The consequences of these differences for the growth and productivity of wheat were minor. A negative effect of saprophytic mycoflora on the yield could not be detected in 1981 and 1982, whereas a small positive significant effect was found in 1980. This stimulation may have been due to competition between necrotrophic fungal pathogens and saprophytic mycoflora. As a result of favourable weather conditions necrotrophic fungal pathogens were very numerous in 1980 and could form an important yield reducing factor. Yield levels may effect the importance of the necrotrophic and saprophytic mycoflora as yield reducing factors. Additionally, in the presence of aphid honeydew captafol was found to be relatively ineffective against saprophytic fungi.     

Relationship Between Production of the Phytotoxin Prehelminthosporol and Virulence in Isolates of the Plant Pathogenic Fungus Bipolaris sorokiniana

A gas chromatographic method was developed to quantify the phytotoxin prehelminthosporol, which is a sesquiterpene metabolite of the plant pathogen Bipolaris sorokiniana. The toxin was extracted from mycelium or culture filtrates, pre-cleaned using solid phase extraction, and analyzed by gas chromatography as a trimethylsilyl-derivative. The detection limit of the method was 5ngl^–1 (signal to noise ratio 4:1) which corresponds to ca. 15ng prehelminthosporol per mg dry weight of mycelium or 15ng prehelminthosporol per ml culture filtrate. The total amount of prehelminthosporol (mycelium plus culture filtrate) increased with cultivation time when examined in six isolates of B. sorokiniana after 6, 9, 12 and 15 days of incubation. The screening experiment of 17 isolates for prehelminthosporol production after 8 days of incubation revealed significant differences in the toxin production between the isolates. The isolates with low toxin production had lower virulence towards barley roots compared to those with higher production of the toxin. However, the virulence did not increase with prehelminthosporol level among the high producing isolates. Prehelminthosporol was also analyzed in a number of related Bipolaris and Drechslera species. In addition to B. sorokiniana, three out of six Bipolaris species (B. setariae, B. zeicola, B. victoriae) produced prehelminthosporol, which indicates that ability to produce prehelminthosporol is conserved among closely-related Bipolaris species.