莲草直胸跳甲在几种非靶标植物上的适合度比较

莲草直胸跳甲是防治入侵杂草喜旱莲子草的引进天敌,为检测莲草直胸跳甲对非靶标植物的影响,选取了29种具有代表性的植物对该天敌进行了3种选择和1种非选择性压力的测试.在全组植物或移除喜旱莲子草组中,莲草直胸跳甲成虫和幼虫对喜旱莲子草和非靶标近缘种莲子草的取食面积均显著大于其它非靶标植物,幼虫还可取食非靶标植物若蘧、反枝苋等;成虫在无喜旱莲子草时可取食若蘧和甜菜.当移除喜旱莲子草和莲子草时,成虫和幼虫对若蘧和甜菜的取食面积分别提高22.33、4倍和1.76、16.42倍.在非选择测试中,成虫和幼虫对喜旱莲子草和莲子草的取食显著高于其它组,其它植物均不能满足其正常发育和生存.研究表明,莲草直胸跳甲对莲子草属植物的适合度最高.     

利用光谱特征评价广聚萤叶甲对豚草的控制效果

为建立快速有效的豚草生物防治效果评价技术体系,采用基于成像光谱遥感技术的多波段光谱辐射仪,研究豚草被广聚萤叶甲取食后冠层光谱反射率的变化规律,并利用冠层光谱特征值评价广聚萤叶甲对豚草的控制效果.广聚萤叶甲的取食会引起豚草的冠层光谱发生变化,在绿光区560nm和近红外区710～810nm处,随着被取食程度的加重,豚草冠层光谱反射率逐渐降低;在黄光区660nm处,随着被取食程度的加重,豚草冠层光谱反射率逐渐升高.豚草被广聚萤叶甲取食后,归一化植被指数、比值植被指数、差值植被指数、再归一化植被指数均显著低于未被取食的对照组.在可见光绿光区560nm处和近红外区710nm和760nm处豚草冠层光谱反射率与其被取食程度均达到显著负相关,故可以将可见光绿光区560nm、近红外区710nm和760nm这3个波段作为监测的敏感波段.     

广东莲草直胸跳甲生物学的观察

空心莲子草 ( Alternanthera philoxeroides)为一种多年生恶性杂草 ,属苋科 ,莲子草属 ,在我国各地又名水花生、空心苋、喜旱莲子草等 ,具有繁殖迅速 ,适应性强和难以用化学除草剂根除的特点 [1 ] 。该草原产南美 ,大约本世纪 40年代传入我国 ,现成为南方各省主要恶性杂草 ,已泛滥成灾 ,给农业和水产养殖业造成极大危害 [2 ]。莲草直胸跳甲 ( Agasicles hygrophila)原产阿根廷 ,是空心莲子草的天敌。李宏科等 [3] 报道了莲草直胸跳甲的大量繁殖及释放技术 ,对应用莲草直胸跳甲的可行性作了研究。吴珍泉等 [4]对莲草直胸跳甲生物学特性进行…     

莲草直胸跳甲羧酸酯酶基因AhCesB1的克隆、序列分析及表达特征

莲草直胸跳甲Agasicles hygrophila是入侵杂草喜旱莲子草的专食性天敌。为进一步明确莲草直胸跳甲寄主专一性的分子机制,通过分析其转录组数据克隆羧酸酯酶(carboxylesterases,Car Es)基因,采用RT-PCR技术从其体内获得1个羧酸酯酶B簇基因并进行生物信息学分析,同时利用实时定量PCR方法检测其在不同身体部位及不同发育阶段的表达特性,并对饥饿处理、取食靶标植物喜旱莲子草和非靶标植物莙荙后该基因的表达水平进行比较。结果显示,克隆得到1条莲草直胸跳甲羧酸酯酶基因的cDNA全长序列,长度为1 851 bp,开放阅读框长度为1 647 bp,编码548个氨基酸,以该基因推导的氨基酸序列与其它物种的CarEs进行聚类分析,发现此基因为羧酸酯酶B簇家族成员,命名为AhCesB1(GenBank登录号KT032151)。实时定量PCR检测结果显示,AhCesB1基因在莲草直胸跳甲3龄期表达量最高,成虫期和蛹期表达量次之,卵、1龄和2龄期表达量相对较低。AhCesB1基因在头和中肠的表达量较低,在其余身体部分表达量较高。取食莙荙后AhCesB1表达量显著增高,为饥饿处理的13.7倍,而取食喜旱莲子草与饥饿处理并无显著差异。表明莲草直胸跳甲AhCesB1在不同发育阶段和成虫不同身体部位具有不同的表达水平,而非寄主植物莙荙可以诱导该基因的表达,推测羧酸酯酶在莲草直胸跳甲代谢次生物质中发挥着重要作用。     

饥饿及取食不同植物后莲草直胸跳甲消化酶差异表达基因筛选

为探究莲草直胸跳甲Agasicles hygrophila体内与寄主专一性相关的消化酶基因,利用前期构建的转录组数据库筛选差异表达的消化酶基因,采用实时荧光定量PCR检测饥饿及取食喜旱莲子草Alternanthera philoxeroides、莲子草Al. sessilis、甜菜Beta vulgaris、莙荙B. v. var. cicla后莲草直胸跳甲成虫体内差异表达消化酶基因的表达量。结果显示,转录组分析共搜索到221个与消化相关的基因,主要编码脂肪酶和蛋白酶;进一步筛选到编码蛋白酶、脂肪酶和糖酶3大类的26个差异表达的消化酶基因。与取食寄主植物喜旱莲子草相比,取食不同非寄主植物和饥饿处理后莲草直胸跳甲成虫体内消化酶基因表达量发生显著变化。除β-半乳糖苷酶(β-galactosidase,β-Gal)基因外,取食不同植物及饥饿处理后莲草直胸跳甲成虫体内4个胰蛋白酶(trypsin,Try)、5个氨肽酶(aminopeptidase,Am)、8个脂肪酶(lipase,Lip)、5个β-葡萄糖苷酶(β-glucosidase,β-Glu)和1个α-葡萄糖苷酶(α-glucosida...     

莲草直胸跳甲在不同生态型空心莲子草上的化蛹适应性

对莲草直胸跳甲在不同生态型空心莲子草上化蛹能力的研究表明：美国和重庆种群对不同生态型空心莲子草的化蛹适应性无显著差异；空心莲子草的生态型是影响莲草直胸跳甲化蛹能力的重要因子，在水生型草上化蛹能力显著高于湿生型和旱生型；水生型空心莲子草的直径大小不影响跳甲的化蛹能力，而陆生型空心莲子草的直径是影响其化蛹能力的重要因子；在陆生型草上，随着生长环境水分的降低，莲草直胸跳甲对直径较大的空心莲子草有很强的选择性；该虫在不同生态型草上的化蛹率与化蛹位置有关。莲草直胸跳甲能有效地控制水生型空心莲子草，对陆生型草可起到一定程度的抑制作用。     

饥饿程度及取食不同植物对莲草直胸跳甲消化酶的影响

为明确莲草直胸跳甲Agasicles hygrophila成虫消化酶的作用,分别采用3,5-二硝基水杨酸法、福林-酚法、碘-淀粉比色法测定其取食喜旱莲子草、莙荙及饥饿48 h后纤维素酶、蛋白酶、淀粉酶的变化,以及饥饿不同时间对3种消化酶的影响。结果表明,取食不同植物后,莲草直胸跳甲成虫的纤维素酶、淀粉酶、蛋白酶活力差异显著,其中取食莙荙后其体内纤维素酶(葡聚糖外切酶、葡聚糖内切酶、β-葡萄糖苷酶)和淀粉酶活力最高,分别为3.07、6.63、6.79、23.48 U/mg,是对照的1.21、3.18、2.43和1.34倍;取食喜旱莲子草后其蛋白酶活力最高,为25.09μg·mg~(-1)·min~(-1)。饥饿不同时间对莲草直胸跳甲成虫体内纤维素酶、淀粉酶、蛋白酶活力有显著影响,随着饥饿时间的延长,纤维素酶、淀粉酶活力均逐渐降低,而蛋白酶活力呈先升高后降低的趋势,饥饿36 h对成虫蛋白酶活力的促进作用最强,为20.64μg·mg~(-1)·min~(-1),是对照的1.11倍;饥饿60 h后其蛋白酶活力最低,仅为10.17μg·mg~(-1)·min~(-1)。表明饥饿初期对莲草直胸跳甲成虫消化酶起促进作用;取食莙荙后可增强其体内淀粉酶、纤维素酶的分解作用,取食喜旱莲子草可增强其体内蛋白酶活力。     

喜旱莲子草天敌——莲草直胸跳甲引种方法介绍

本文论述了作为入侵杂草喜旱莲子草优势天敌——莲草直胸跳甲的长距离和短距离引种方法,对其三种虫态的引种方法分别做了介绍。成虫适宜长距离和短距离引种;幼虫和卵适合做短距离引种。这为成功防治恶性杂草喜旱莲子草提供了技术指导。     

喜旱莲子草次生代谢物对莲草直胸跳甲谷胱甘肽S-转移酶和淀粉酶活性的影响

为明确喜旱莲子草的次生代谢物对其专食性天敌-莲草直胸跳甲Agasicles hygrophila成虫解毒酶和消化酶的影响,利用不同浓度的橙花叔醇、齐墩果酸和甜菜碱浸叶处理喜旱莲子草Alternanthera philoxeroides,连续饲喂莲草直胸跳甲1~3 d后,测定莲草直胸跳甲谷胱甘肽S-转移酶(GSTs)和淀粉酶(AMS)的活性变化。结果表明,橙花叔醇、齐墩果酸和甜菜碱均能抑制莲草直胸跳甲的GSTs活性,0.1%橙花叔醇和20%甜菜碱处理24 h时的GSTs活性最低,分别为45.67 U/mg和53.95 U/mg,0.2%齐墩果处理72 h时的GSTs活性最低,为98.77 U/mg,且莲草直胸跳甲对橙花叔醇的刺激存在着一种适应机制;0.5%橙花叔醇和0.1%齐墩果酸处理24 h后的GSTs活性最高,分别为243.10 U/mg和250.22 U/mg,是对照的1.55倍和1.59倍,存在诱导激活现象。甜菜碱对莲草直胸跳甲的AMS活性有明显的抑制作用,20%甜菜碱处理72 h后AMS活性最低,为1.01 U/mg,是对照的55.92%。表明喜旱莲子草3种次生代谢物均能抑制谷胱甘肽S-转移酶活性,其中橙花叔醇和齐墩果酸对谷胱甘肽S-转移酶有诱导激活作用,而甜菜碱对淀粉酶抑制作用较强。     

入侵种喜旱莲子草——主要天敌昆虫

喜旱莲子草是一种水陆两栖的重要入侵杂草,中国首批16种重要入侵物种之一。本文介绍了生物防治喜旱莲子草的天敌昆虫莲草直胸跳甲Agasicles hygophila、Vogtia malli、Amynothrips anderso- ni、阿根廷跳甲Disonycha argentinensis、Systena nitentula和虾钳菜披龟甲Cassida piperata等天敌的分类地位、形态特征、生物学、生态学特性以及国内外寄主专一性研究、释放效果与评价。     

Use of multispectral radiometry for assessment of rhizoctonia blight in creeping bentgrass

ABSTRACT The ability to identify diseases early and quantify severity accurately is crucial in plant disease assessment and management. This study was conducted to assess changes in the spectral reflectance of sunlight from plots of creeping bentgrass during infection by Rhizoctonia solani, the cause of Rhizoctonia blight, and to evaluate multispectral radiometry as a tool to quantify Rhizoctonia blight severity. After inoculation of 6-year-old creeping bentgrass turf with R. solani anastomosis group 2-2, reflectance of sunlight from the foliar canopy was measured at light wavelengths of 460 nm (blue) to 810 nm (near infrared [NIR]), at 50-nm intervals. Visual estimates of disease severity and percentage of canopy reflectance were made daily throughout each of three epidemics of Rhizoctonia blight from the onset of visible symptoms until maximum disease severity was reached. In each experiment, linear regression analysis revealed a significant reduction in the percentage of NIR (760 and 810 nm) reflectance as disease severity increased. However, in the majority of analyses, regression models explained <50% of the variability between components. Multispectrum radiometry appears to function best when used to assess differences in disease severity at discrete points in time rather than over an entire epidemic.     

异质生境对生防昆虫莲草直胸跳甲数量分布的影响

昆虫的种群动态和数量分布与环境因素密切相关。本研究通过在中国南方空心莲子草大规模入侵的区域分别设置水、陆样地,采用曲线回归和冗余分析等方法探讨了异质生境中空心莲子草形态特征、入侵群落植物多样性及无机环境对生防昆虫莲草直胸跳甲数量分布的影响。结果显示:水、陆两境中莲草直胸跳甲数量均随着空心莲子草株高增加而上升;莲草直胸跳甲数量随水生型空心莲子草分枝数及入侵盖度的增加而上升。莲草直胸跳甲数量与陆生群落植物物种多样性无显著相关性,但在水生环境中,莲草直胸跳甲数量随群落的Simpson、Shannon和Pielou指数上升而显著下降。水、陆两境中决定莲草直胸跳甲数量的主导性环境因子均为年均气温、纬度和海拔。研究结果可为入侵植物的生物防治及引进天敌提供参考。     

Early assessment of the yield loss in rice due to the brown planthopper using a hyperspectral remote sensing method

The brown planthopper (BPH) is an important pest in rice. Rice losses due to BPH's damage are often more than 10% of yield. Assessments on loss rates from BPH are now basically dependent on experiential indices. However, early assessments on rice yield losses using hyperspectral data are still rare. In this study, reflectance from rice canopy was measured in net cages after different densities of BPH release. Results showed that reflectance in the near-infrared region (750–1000 nm) from milk grain stage, and in 400–531 nm and 567–705 nm from mature grain stage was closely related to BPH density. These spectral indices: red-edge parameters (λ_r, Dλ_r, Sλ_r), ratio of the maximal reflectance in green (490–560 nm) to minimal reflectance (640–740 nm) in red (R_GREEN/R_RED), ratio of the near-infrared peak (R_NIR) to R_RED, normalized difference vegetation index between R_NIR and R_RED and soil-adjusted vegetation index (SAVI) from both milk and mature grain stages, indicated BPH densities well. As expected, rate of loss in rice grain was higher with increasing BPH density. SAVI, Dλ_r, Sλ_r and reflectance at 760 nm (R₇₆₀) from milk grain stage were significantly correlated with rates of loss in panicle, and 1000-grain weight and multiple-linear regression models for detecting loss rate were established. The hyperspectral reflectance from rice at milk grain stage can be used to assess rice yield losses due to BPH and improve management policies.     

亚洲玉米螟为害后玉米冠层光谱变化和产量损失研究

2006年在河北农林科学院植保所农场夏播高感亚洲玉米螟的玉米品种郑单958上,于大喇叭口期人工接种2龄玉米螟幼虫以造成不同梯度为害,利用便携式遥感光谱仪(ASD FieldSpec UV/VNIR)在玉米不同生育期收集冠层光谱信息,调查食叶级别,并在收获时统计蛀孔率和产量。结果表明:(1)各生育期食叶级别和对应生育期内的冠层光谱反射率值呈显著负相关,且各个级别之间方差分析差异显著;(2)各波段冠层光谱反射率值和每株虫孔数量的相关性分析得到相关性曲线,750～900nm相关系数较高,可作为监测的敏感波段;(3)乳熟期光谱数据、平均每株虫孔数量和产量及产量损失率之间均可建立极显著回归方程。用光谱仪所测数据估测产量损失率的精确度比用传统查虫数据估测产量损失率的精确度高,且省时省工。     

Ratio of rice reflectance for estimating leaf blast severity with a multispectral radiometer

 Rice reflectance was measured to determine the spectral regions most sensitive to leaf blast infection with a multispectral radiometer. As disease severity increased, reflectance also increased in the 400–500 nm (blue), 570–700 nm (red), and 900–2000 nm regions but decreased in the 500–570 nm and 700–900 nm regions. The increased reflectance in the blue and red regions may be attributed to decreased chlorophyll and carotenoid contents in response to the blast infection. The maximum and minimum reflectance differences occurred at 680 nm and 760 nm for the nondiseased and diseased rice, respectively. The spectral location of maximum sensitivity was 675 nm regardless of disease severity. Rice reflectance ratios were evaluated as indicators of leaf blast severity. Two ratios, R550/R675 (reflectance at 550 nm divided by reflectance at 675 nm), and R570/R675 quantified the significant disease severity. These wavelengths were selected based on the sensitivity minima and maxima. The ratios of nondiseased rice plants varied depending on growth stage. The variation in ratios must be considered when they are used to estimate leaf blast severity. Received: April 2, 2002 / Accepted: August 12, 2002     

空心莲子草叶(虫甲)的寄主专一性测验

空心莲子草叶(虫甲)原产阿根廷,是空心莲子草的天敌。1987年由美国佛罗里达州引入北京,在室内用代表21个科的39种主要经济作物、观赏植物及与空心莲子草近缘或形态相似的植物,进行了叶(虫甲)食性测验,结果表明:该天敌为单食性,除自然寄主外,不取食其它植物;在人为强制饥饿条件下,仅轻微取食马齿苋、白菜、莴苣,但不能完成生活史。这种天敌在我国可以安全利用。     

苹果害螨为害叶等级的光谱鉴别法

本文用室内光谱分析法找出了苹果害螨为害等级与680nm/800nm这一比值光谱指数的定量关系,并证明这种害虫在为害苹果树时对树冠没有方位性选择。这种病虫害为害与光谱相关关系的研究结果可使为害等级鉴别客观化和定量化,并为病虫害的遥感监测提供了依据。     

Ground-based remote-sensing measurements for early detection of plant stresses

Biotic and a biotic stresses are responsible for significant yield reduction and qualitative depreciation of agricultural products. In planning plant protection, one of the first elements needed is early and accurate detection of the presence and extent of damage. Remote sensing is a viable technique for such detection, since biotic and a biotic agents modify the electromagnetic characteristics of leaf and canopy surfaces. Damage can be detected at an appropriate wavelength, according to the nature of the anatomical or physiological alteration produced. The objective of this paper is to outline the potentialities of remote-sensing techniques in this field. At the leaf scale, laboratory devices were able to register leaf tissue alterations before they were visually detectable, by measuring spectral reflectance in the 0.4-1.1 μm interval and emittance in the thermal infrared band. At field scale, whole canopy modifications can be successfully detected by means of multispectral radiometers (in the visible and near-infrared bands) or using thermal infrared sensors.