带田玉米上棉铃虫危害特性的研究

棉铃虫在青海省东部农业区,以第２代幼虫危害玉米,７月下旬中期至８月上旬中期为卵盛期,平均百株卵量达２６.３粒。玉米雌穗和叶片正面是成虫产卵的主要部位,占全株着卵量８２.０１％。自然条件下卵历期平均为３.４１ｄ,幼虫历期平均为２１.２ｄ。一般情况下一个雌穗上只有１条幼虫,一生危害玉米籽粒２～３４粒,少有转株、转穗危害现象,平均损失粒重１.９１４７ｇ,损失率为１.４５％左右。     

科技文摘

玉米田 3种螟虫转移为害规律及防治对策 /吴立民…(江苏省新沂市农业局　 2 2 1 40 0 )∥昆虫知识 .— 1 999,3 6( 5) .— 2 60～ 2 63桃蛀螟、玉米螟、高粱条螟是我国春夏玉米田的主要害虫。玉米心叶期的幼虫集中为害心叶 ,至心叶末期 ,转移为害雄穗 ,破口露穗期心叶不再受害 ,集中为害雄穗 ,抽雄开花期 ,叶鞘内侧的虫量增加 ,部分幼虫开始蛀茎为害 ,开花结束 ,幼虫大量转向雌穗顶端 ,取食花丝、穗轴及幼嫩籽粒。 3种螟虫的低龄幼虫都趋幼嫩且营养丰富的心叶、雄穗、雌穗和叶鞘为害 ,三龄以后才逐步转移为害茎秆。 3种螟虫的混合种群在玉米…     

二化螟在茭白上的钻蛀行为及其防治方法

研究了二化螟在茭白植株上的转移、钻蛀和产卵行为以及取食选择性,并根据其行为特性,制订合理的药剂喷施方法.结果表明,二化螟90%以上的卵产在茭白的叶片上,其余部分产在叶鞘上.产卵的主要叶位是心叶、倒一叶和倒二叶.超过50%的卵块集中在叶片距叶枕0～60cm的部位.幼虫孵化后,蚁螟蛀入的部位一般在叶枕以下的叶鞘内侧,多集中于倒四、倒五叶鞘.2龄后开始钻蛀内侧叶鞘,并蛀入茭白茎的内芯,二化螟幼虫在茭白植株上通常从叶片转移到叶鞘进行钻蛀危害.幼虫嗜食茭白茎部,其次为茭白果肉和叶鞘,对叶片几乎不取食.使用叶鞘喷施杀虫可达到对茭白进行全株喷雾同样的防治效果,并可节省40%～50%的用药量,经济和生态效益十分明显.     

亚洲玉米螟危害蛀孔在春玉米上的分布及其与产量损失的关系

亚洲玉米螟1、2代幼虫在河北张家口春玉米上的危害蛀孔 ,分布在雌穗着生节 (含穗柄 )及其上、下1～3节上的百分比分别为89.9%和85.7%。 1代幼虫蛀孔42.0%分布在雌穗下 1～3节 ,26.8%分布在雌穗上1～3节 ,每株平均有1.8个和2.1个蛀孔。玉米品种逐单 1号和自 330分别减产 19.3%和 23.5%。蛀孔数与产量呈极显著负相关 ,每株增加 1个蛀孔 ,两个品种产量损失率分别为 11.04%和 13.17%。雌穗上部 1个蛀孔的产量损失系数为3.9和 2.9,雌穗下部 1个蛀孔为 16.4和 12.4。 2代幼虫蛀孔 45.7%分布在雌穗以上茎节 ,28.5%分布在雌穗以下茎节 ,每株有 1～6个蛀孔时 ,蛀孔数与产量损失相关系数均未达到 5%的显著标准。     

亚洲玉米螟在玉米和甘蔗不同种植模式下的产卵行为

为明确玉米和甘蔗间作对亚洲玉米螟产卵行为的影响,在尼龙网室研究了亚洲玉米螟在玉米和甘蔗不同种植模式下的产卵时间、产卵部位及产卵量的差异。结果表明,不同种植模式下亚洲玉米螟均于23∶00开始产卵,02∶00~03∶00达产卵高峰。单作甘蔗、单作玉米和间作甘蔗叶背的玉米螟卵块和卵粒数均高于叶面,而间作玉米叶背与叶面的玉米螟卵块数无显著差异,叶背的卵粒数高于叶面。单作玉米叶脉的玉米螟卵块和卵粒数均显著高于叶缘;间作玉米和单作甘蔗叶脉与叶缘卵块数间无差异,但叶脉处卵粒数高于叶缘,间作甘蔗叶脉的卵块数高于叶缘,叶缘卵粒数高于叶脉。单作甘蔗叶背的亚洲玉米螟卵块主要分布在距叶鞘69.14 cm处,而叶面的卵块主要分布在距叶鞘21.09 cm处;间作甘蔗叶背和叶面卵块分布于距叶鞘35.17 cm和12.34 cm处,二者差异显著。单作玉米上亚洲玉米螟卵块仅分布于叶背沿叶脉远离叶鞘处,而间作玉米叶背和叶面卵块分布于近叶鞘。表明玉米和甘蔗间作对亚洲玉米螟雌蛾产卵选择性具有明显的影响。     

玉米田三种螟虫化蛹规律的研究

经连续４年的观察，玉米螟和高粱条螟在玉米茎秆内和叶鞘内侧化蛹的比例分别为８５．３％和８３．６％，在雌穗上化蛹的比例为１４．３％和１６．４％，桃蛀螟在叶腋处和雌穗顶端化蛹的比例为８６．５％，茎秆内化蛹的比例只占１３．５％。根据３种螟虫各代化蛹高峰期均明显而集中，可简化调查方法用于测报。     

草地贪夜蛾卵块在玉米植株上的空间分布

本研究调查了草地贪夜蛾卵块在田间玉米植株上的空间分布,发现草地贪夜蛾卵块主要分布于植株中部,即玉米小喇叭口期倒3叶与倒4叶、吐丝期倒5叶与倒6叶上卵块最多,在小喇叭口期主要分布在叶正面,吐丝期主要分布于叶背面,距叶尖平均距离分别为23.4 cm和35.2 cm。为玉米上草地贪夜蛾卵的调查和防治提供了参考。     

国内一种玉米新病害--玉米黑腐病

1999年7月云南省元谋县城郊玉米地发现一种玉米新病害,发病面积大约70hm2.其典型症状表现为植株矮化,节间缩短,叶片密集簇生,叶片上有黄绿相间的条斑.叶鞘上有坏死或腐烂病斑,幼穗腐烂,不实,严重者绝产,颗粒无收.从坏死或腐烂的叶鞘和果穗上可镜检到分生孢子及分生孢子梗.纯化培养后,并按柯赫氏法则进行接种试验,病原鉴定为柔弱无枝孢Acladium tenellum(Berk.& Curt.)Subram.comb.nov..本文对病害症状、病原形态、发病情况等进行了详细研究,确定该病为玉米一种新病害.     

怎样檢查药剂防治玉米螟的效果?——答山东讀者張超同志

检查药剂防治玉米螟的效果,最可靠的方法是“剖秆检查”。即用不同药剂处理被害株,经过一定时间,将供试植株齐地面割下,剖秆检查。检查心叶期的植株,一般可先在心叶最下面的一张叶片(指宽大的叶片,不是靠近地面的)的叶鞘处用小刀截断,就能将叶片逐一展开,进行仔细的检查;然后再剖查茎秆部分。检查穗期的植株,一般先摘下雌穗,剥去苞叶进行检查;其次将叶片逐一拆除,检查叶鞘和茎秆交接处;最后再剖查茎秆。根据不同试验目的,具体记载方法可分以下两类:     

不同夏玉米品种穗部主要害虫发生现状调查

在夏玉米穗期,对16个不同品种雌穗上棉铃虫、玉米螟、桃蛀螟发生情况进行了调查。结果显示,河北馆陶夏玉米穗部害虫棉铃虫、玉米螟、桃蛀螟混合发生,不同品种间虫量水平差异显著。各品种平均百株虫量,以桃蛀螟最高,达38.7头/百株;玉米螟次之,为16.0头/百株;棉铃虫最低,为5.6头/百株。各品种平均百株总虫量60.3头/百株。其中,总虫量最高的品种为北承190,高达195.6头/百株;同时,万盛69、郑单958、登海710品种的平均百株总虫量低于13.3头/百株,存在某种程度的抗虫性。不同品种受害穗率和粒腐穗率不同,平均受害穗率83.3%,最高100%,,平均粒腐穗率33.7%,最高74.4%;受害穗率与粒腐穗率变化趋势一致,较高的受害穗率引起玉米粒腐、穗腐的发生。     

不同品系赤眼蜂对烟青虫卵的寄生选择性

采用棚室笼罩试验，研究了松毛虫赤眼蜂和螟黄赤眼蜂的不同品系对不同卵龄烟青虫卵的寄生选择性、松毛虫赤眼蜂HJS品系对烟草不同叶位、叶面上的烟青虫卵及不同植物（辣椒和烟草）上的烟青虫卵的寄生选择性。结果表明，松毛虫赤眼蜂HJS、YYS品系和螟黄赤眼蜂JDM品系对0～12h烟青虫卵的寄生率显著高于12～36h的卵；而螟黄赤眼蜂GGM品系对该二卵龄烟青虫卵的寄生选择性无显著差异。不论位于叶正面、叶背面还是整叶上的卵，松毛虫赤眼蜂HJS品系均对倒10～12叶位的卵寄生选择系数最高，其次为倒13～15叶，对倒1～6叶均较低，这与烟青虫产卵对叶位的选择不同；HJS对所有叶位叶正面烟青虫卵的寄生选择系数均高于对背面的，并以倒1～3和倒4～6叶位最为明显，且HJS对叶正面卵的寄生倾向和程度与烟青虫雌蛾在该叶位正面产卵的倾向及程度存在差异，该差异因叶位不同而不等。HJS对辣椒上烟青虫卵的寄生选择系数较高，而烟青虫偏好产卵于烟草。     

草地贪夜蛾在云南冬季甜玉米上的生物学习性及为害状观察

田间调查表明,2019年1月草地贪夜蛾入侵云南省后,在德宏州4县市冬季甜玉米上均有发生为害,世代重叠严重。5月份以前主要为害冬季甜玉米,平均被害株率和百株虫量分别为4.55%和5.72头。成虫喜产卵于玉米心叶上部正面,1～6龄幼虫可取食为害玉米的生长点、叶片、雄穗和果穗。其中1～3龄幼虫具有聚集为害习性和趋嫩性,常取食幼嫩的心叶叶肉,4～6龄幼虫常啃食叶片和雄穗,咬断生长点,在心叶期和抽雄期形成典型被害状。心叶期和抽雄期玉米被害株率较高,且抽雄期被害株率显著高于苗期和灌浆期。     

Experience-altered oviposition responses to a neem-based product, Neemix, by the diamondback moth, Plutella xylostella

The oviposition responses of the diamondback moth, Plutella xylostella L., to Neemix 4.5, a neem-based oviposition repellent/deterrent, with or without previous experience were studied in the laboratory on plain aluminum foil sheets, on aluminum foil sheets coated with cabbage juice, and on cabbage plants. In the plain aluminum foil sheet experiment, the females without prior experience of Neemix (inexperienced females) deposited more eggs (66.2%) on sections with untreated sheets than on sections with Neemix-treated sheets (33.8%), indicating that the inexperienced females were significantly repelled and/or deterred by Neemix. In contrast, the Neemix-experienced females deposited more eggs (69.2-69.7%) on sections with Neemix-treated sheets than on sections with untreated sheets (30.3-30.8%), implying that the females were not repelled and/or deterred by Neemix following an experience. In the tests using egg-laying sheets coated with cabbage juice or with cabbage juice plus Neemix, the inexperienced females deposited more eggs (63.8%) on the sections with sheets treated with cabbage juice only than on the sections with sheets coated with cabbage juice and Neemix (36.2%), indicating that inexperienced females were repelled and/or deterred by Neemix. Similarly, Neemix-experienced females deposited more eggs (62.2-65.6%) on the sections with sheets treated with cabbage juice plus Neemix than on the sections with sheets treated with juice only (34.4-37.8%), suggesting that the females were not repelled and/or deterred by Neemix following an experience. On cabbage plants, inexperienced females oviposited similar numbers of eggs on both Neemix-treated (50.8%) and untreated plants (49.2%). However, the Neemix-experienced females oviposited more eggs on the plants treated with Neemix (56.3%) than on untreated plants (43.7%), indicating that the females were attracted by Neemix-treated plants following an experience. The significance of this study for applications of insect repellents/deterrents in pest management is discussed.     

抗生素溶杆菌13-6对玉米小斑病的生防作用机制初步研究

 玉米小斑病是玉米生产中的重要病害之一,本研究利用传统植物病理学和荧光定量PCR方法,研究抗生素溶杆菌对玉米小斑病菌(Bipolaris maydis)的生防效果和作用机制,为玉米小斑病的生物防控提供理论依据。结果显示,抗生素溶杆菌13-6对玉米小斑病菌丝生长和孢子萌发具有显著抑制作用,造成菌丝顶端生长受阻、表面粗糙,部分菌丝破裂,代谢粗提物抑制孢子萌发率高达92.19%,PI荧光染色显示病原菌孢子破裂并死亡。温室叶面喷施13-6发酵液、发酵液粗提物后显著降低玉米小斑病病情指数,相对防效分别达到42.43%和68.06%。诱导抗性实验表明:13-6对玉米小斑病的诱导防效达49.57%。玉米植株体内相关抗性基因表达结果显示,在灌根处理3 d后,抗病相关基因PR1和PR5、脂氧合酶LOX、乙烯受体ETR1均被激活表达,9 d达到最大值。研究证实抗生素溶杆菌13-6对玉米小斑病具有较好的生防效果,直接喷施可减缓玉米小斑病的发生,灌根施用使植株产生诱导抗性。     

Yield loss of sweet corn cultivars in response to defoliation and to infection byexserohilum turcicum

The effect of northern leaf blight (NLB) or leaf defoliation on the yield of nine sweet corn cultivars was studied in field experiments. Plants were defoliated or infected in the bottom, middle or top third of the leaf canopy. The effect of defoliation or infection on yield was significantly higher for plants treated 55 days after planting than for those treated 70 days after planting. Cultivar response differed significantly for both treatments, the most sensitive cultivar being ‘Jubilee’ and the least sensitive being Ssupersweet 7900. In all cases, the highest yield loss was recorded when the middle third of the leaf canopy was treated. The relative importance of the top third of the leaf canopy increased if the treatment was done 3 weeks before harvesting. This study emphasized the importance of leaf position, cultivar, and plant growth stage for evaluating losses caused by NLB, and may explain the failure of various models to describe yield loss due to NLB.     

Uneven distribution of two potyviruses (feathery mottle virus and sweet potato latent virus) in sweet potato plants and its implication on virus indexing of meristem derived plants

Abstract

The distribution of two sweet potato potyviruses, FMV and SPLV, was assessed in three plants infected with both viruses and in one plant infected with FMV only. All leaves, the top and basal sections of the main stem, and branch sections were tested by ELISA. Both symptomless leaves and leaves showing symptoms including purple rings, chlorotic spots, mottle or discoloration were found to contain the viruses. However, neither could be detected in every leaf or stem piece. SPLV was found in a lower proportion of leaf and stem samples than FMV. This indicates that the two viruses are either very unevenly distributed within sweet potato plants or that the virus concentration in some parts is below the detectable level. Testing of each leaf is recommended for reliable virus indexing of small, meristem‐derived sweet potato plantlets, if the ELISA method is used. Additional indexing of all ELISA‐negative materials by grafting to susceptible indicator plants is nevertheless still necessary.     

Spatial variability of leaf wetness under different soil water conditions in rainfed jujube(Ziziphus jujuba Mill.) in the loess hilly region,China

Leaf wetness provides a wide range of benefits not only to leaves,but also to ecosystems and communities.It regulates canopy eco-hydrological processes and drives spatial differences in hydrological flux.In spite of these functions,little remains known about the spatial distribution of leaf wetness under different soil water conditions.Leaf wetness measurements at the top(180 cm),middle(135 cm),and bottom(85 cm)of the canopy positions of rainfed jujube(Ziziphus jujuba Mill.)in the Chinese loess hilly region were obtained along with meteorological and soil water conditions during the growing seasons in 2019 and 2020.Under soil water non-deficit condition,the frequency of occurrence of leaf wetness was 5.45%higher at the top than at the middle and bottom of the canopy positions.The frequency of occurrence of leaf wetness at the top,middle and bottom of the canopy positions was over 80%at 17:00?18:00(LST).However,the occurrence of leaf wetness at the top was earlier than those at the middle and bottom of the canopy positions.Correspondingly,leaf drying at the top was also latter than those at the middle and bottom of the canopy positions.Leaf wetness duration at the middle was similar to that at the bottom of the canopy position,but about 1.46-3.01 h less than that at the top.Under soil water deficit condition,the frequency of occurrence of leaf wetness(4.92%-45.45%)followed the order of top>middle>bottom of the canopy position.As the onset of leaf wetness was delayed,the onset of wet leaf drying was advanced and the leaf wetness duration was shortened.Leaf wetness duration at the top was linearly related(R²>0.70)to those at the middle and bottom of the canopy positions under different soil water conditions.In conclusion,the hydrological processes at canopy surfaces of rainfed jujube depended on the position of leaves,thus adjusting canopy structure to redistribute hydrological process is a way to meet the water need of jujube.     

合成性信息素迷向法防治玉米螟

在张家口地区越冬代亚洲玉米螟交配场所(小麦和大蒜田)用合成性信息素干扰螟蛾交配。试验结果证明:减少了玉米田内第一代种群的发生量。每公顷使用150～750mg,对螟蛾交尾的定向抑制率分别达到93.2～100％,交配抑制率分别为47.8～85.8％。每公顷600～750mg、每个散发器0.1～0.4mg的4个处理和每公顷450mg、4500个散发器的处理,交配抑制率高达79.3～85.8％,并取得百株卵量减少77.6～89.3％,以及百株蛀孔减少74.5～85.6％的防治效果。