德国为除草剂失效找到解决途径

德国马克斯·普朗克发育生物学研究所的科学家首次直接测量了植物突变过程的速度。该研究用全新视角展现了进化的基本过程，解释了除草剂为何使用几年后就会失效等问题。相关研究发表在近日的《科学》杂志上。     

植物病害分子流行学概述

 本文概要地介绍了植物病理学新研究领域——植物病害分子流行学的基本概念、进展和在几个主要方面的研究实例。分子生物技术在病原鉴定方面得到了广泛应用;定量的分子生物技术在测定病菌初侵染源方面显示出特有的快速、准确的优势;分子流行学应用分子生物技术监测病害和病原菌群体的动态,克服了传统流行学方法的弱点;作为有力的补充,分子生物技术正在用于探讨和推测病原菌远距离传播的路径,并注重研究病原菌群体的时、空动态变化,病原菌的长期进化,以及与病害发展的关系;病原群体的竞争将得到更深入的研究以揭示其变化是如何导致植物病害大流行;应用分子流行学手段,植物抗病性的鉴定将大大加速和简化;病害防治策略的制定将具有更科学的依据。宏观与微观研究手段的结合将越来越显示其在植物病害流行学研究中的巨大潜力。     

应用昆虫生命表定量评价外来实蝇入侵力

<正>昆虫生命表是对昆虫种群系统研究过程中的一套重要技术,生命表主要利用存活率、瞬时死亡率、死亡分布和生命期望等参数描述昆虫的生活史,生命表可广泛用于昆虫发育、生物防治、进化、入侵等研究（Hong et al.,2022）。实蝇广泛分布于世界各地,是为害果蔬的重要害虫之一,其中约250种具有重要经济意义（Leonardo et al.,2017）。     

植物与病原物互作中的细胞程序化死亡

细胞程序化死亡(PCD)广泛存在于动植物的生长发育或抗逆过程中,而植物与病原物互作中的PCD已成为当前植物病理学的研究热点之一。本文从植物细胞程序化死亡的概念、检测方法、植物与病原物互作间的细胞程序化死亡及调控机理等方面进行了简要概述。     

昆虫生态激素及其利用

依昆虫激素的进展情况,基本可将其分为两大类:一类是内激素,主要是由昆虫内分泌器官分泌的、能在体液内流动的活性物质,它能调节和控制昆虫的生长、发育、变态、滞育、交配、生殖以及一般生理代谢作用。另一类是外激素,它是由昆虫体某一器官或组织所分泌的、能在体外流动的活性物质,它能借空气或其他媒介散布到体外影响同种(有时也影响异种)其它个体的特殊行为。 近几年来生态学有了重大发展,人们在化学生态领域中对生物间相互关系的形成进行了广泛的研究,发现某些化学物质起着重要的作用。昆虫与昆虫、昆虫与植物之间的联系很大程度上也是依赖化学物质传递信息,如昆虫求偶、寻找食物、定向栖息搜索寄主,受到侵扰时向同类告警等行为都存在     

啮齿动物的外激素

动物分泌物和排泄物中的一些化学物质,在同种个体间起着传递信息的作用。昆虫外激素的研究进展较快,已分离鉴定了几百种外激素,其中有几种已用于虫害的预报和防治。昆虫外激素工作的成就激起了对哺乳类外激素的研究,近十余年来,进行了大量的工作。为了便于灭鼠工作者的参考,本     

因危害授粉昆虫而饱受诟病的杀虫剂

正欧盟正在研究是否应禁用一种流行的杀虫剂,相关研究人员在认真评估这种化学物质对蜜蜂和其他授粉者具体有多大的危害。2008年4月,德国巴伐利亚州南部和莱茵河上游河谷地区成千上万的蜜蜂并没有像往常一样在早晨离开蜂箱,而是不断地在蜂箱外绕行并大量死去。在随后的两周中,超过11 500个蜂群出现了这种神秘的大量死亡现象,死去蜜蜂的尸体堆积如山。"这是一场灾难。"在霍恩海姆大学研究蜜蜂健康的彼     

灾变理论及其在植保领域里的应用

一、灾变理论浅介 灾变理论(Catastrophe theory,又译作突变理论)是由法国著名数学家R·托姆(Ren'e Thom)提出的一种描述不连续变化的理论。托姆1972年发表的专著《结构稳定性和形态发生学》(Stabilite' structurelle et Morphoge'ne'se)标志着这一新的数学理论的问世。由于灾变理论可以很好地解释并推导出诸如水的相变、弹性结构的塌陷、冲击波的形成等经典理论问题,而且可以说明社会领域和生命领域里很难处理的现象:如狗由“恐惧”和“愤怒”两个因素控制下的“攻击”与“逃跑”行为共同存在时产生的“狗急跳墙”行为;在细胞分化时由于生物体内化学物质浓度的变化(在时空上是连续的)会分化出不同的细胞、出现空腔和不连续的分界面现象;以及国家进行的决策的更替和知觉的多稳态等现象,使灾     

活性氧参与调控植物生长发育和胁迫应激响应机理的研究进展

复杂多变的自然环境使植物进化出复杂而又巧妙的机制来感知外部信号,并对外部环境的变化做出适应性调整。在这种信号整合和决策过程中起关键作用的一类物质是活性氧(ROS)。细胞内、外产生的ROS与Ca~(2+)和电信号相互偶联组成的ROS波,向"友邻细胞"或远端细胞进行快速信号转导,进而伴随着多种信号组分共同完成应激响应表达。而ROS的产生与清除平衡关系决定了ROS在植物生长发育、器官发生和抗逆方面的作用。系统结并讨论了ROS的产生来源、信号传导机制、响应表达及ROS引起的细胞程序性死亡的最新研究进展。为深入了解ROS激活相关基因的表达,进而研究触发信号转导通路,使植物积极、高效地应对各种内在或外源的刺激信号,以调控植物的生长发育或适应胁迫环境,提供新的观点和见解。     

植物健康概念的商榷

植物健康是经常在植物科学尤其是植物保护领域被使用的术语,但迄今仍然没有一个明确并普遍被认可的概念。通过梳理和总结不同哲学思想下植物健康概念的探讨和争论,试图在分析现有成果的基础上,获得植物健康概念的科学内涵,同时结合中国哲学观念提出了"特定遗传基质的植物(种或品种或生物型等)生长在适宜的环境中(土壤、水分和气候),没有受到其他生物和非生物(环境)因子侵扰和伤害,各种生理功能平和或平衡的自然状态,植物的这种状态就是植物健康"的概念,明确了植物健康的动态性质及阐述了植物健康下的植物种群健康,并对依据这个概念从事农林生产进行了剖析,供大家商榷。     

Organochlorine residues and mortality of herons

Since 1966, 72 herons found dead or moribund in the field have been analyzed for organochlorine chemicals. In addition, 36 herons were obtained through systematic collections, and carcasses were analyzed to determine sublethal exposure to organochlorines. Brains of birds found dead or moribund were analyzed to determine whether the birds had died of organochlorine poisoning. Residues of DDE were found most frequently (96 of 105 carcasses analyzed), PCBs were second (detected in 90 carcasses), and dieldrin and TDE (detected in 37 and 35 carcasses, respectively) were about equal as third and fourth most frequent. Endrin, mirex, toxaphene, and HCB were found least often (8, 9, 9, and 9 carcasses, respectively). At least one organochlorine was found in each carcass, except for six heron chicks found dead in a Maryland heronry. DDE and PCBs were present in highest concentrations; they exceeded 100 ppm in two birds each. Organochlorine concentrations were almost always higher in adult herons than in immature birds. All birds that had hazardous or lethal concentrations in the brain were adults, and most were great blue herons (Ardea herodias). Dieldrin was the chemical most often considered responsible for death. Herons died of suspected DDT and dieldrin poisoning years after the chemicals were banned in the United States. More than 20 percent of the herons found dead or moribund had lethal or hazardous concentrations of organochlorines in the brain.     

Necrotrophic behaviour of Erwinia amylovora in apple and tobacco leaf tissue

An important issue related to the epidemiology of fire blight, a devastating disease of apples and pears, is how its causal agent, the bacterium Erwinia amylovora, survives and disseminates in the environment. Almost no information is available on the possibility of this pathogen overwintering as a necrotroph. In this study, bacterial survival in dead apple and tobacco (a non‐host) leaf tissues was addressed. In necrotized leaves collected 5, 6, 7 and 8 months following shoot inoculation of apple trees, viable E. amylovora cells were present in over 50% of samples from the midrib and in over 10% of samples from lateral veins, but were never found in parenchyma. Using a PCR‐based method, pathogen DNA was detected in more than 50% of samples that were found to be free of viable cells by conventional plating out. However, PCR analysis was insufficient to distinguish between the DNA of viable and dead bacteria. Sugars appropriate for bacterial growth were found in dead apple leaves. In spot‐inoculated attached apple and tobacco leaves, a remarkable increase in the bacterial population was observed in lesions that developed as a hypersensitive response (HR). As in other necrotrophic interactions, bacterial proliferation was associated with massive hydrogen peroxide production and progression toward plant cell death. The results indicate that E. amylovora has an ability to survive as a semi‐necrotroph or necrotroph, which allows for overwintering in dead apple leaves.     

Evidence for recent evolution in an invasive species,Microstegium vimineum,Japanese stiltgrass

The establishment and spread of invasive plants are often associated with a ‘general‐purpose genotype’, with a corresponding high degree of phenotypic plasticity when introduced to a new environment. Evolutionary potential of invasive species following introduction should also be considered, however, as such changes can facilitate rapid range expansion. In this study, we utilised seed from three geographically distinct mid‐Atlantic populations of an invasive species, Microstegium vimineum (Japanese stiltgrass), to assess whether populations varied in their biomass and reproductive responses to light and nitrogen under neutral glasshouse conditions. To assess evolutionary adaptation, we quantified and correlated the abiotic environment from each collection location with the final biomass and seed production of that population under common glasshouse conditions. For M. vimineum, growth and reproductive responses to a common set of abiotic parameters (e.g. light) under these conditions indicated considerable phenotypic variation between and within populations. Interestingly, the degree of variation of seed production and final biomass among populations in the glasshouse was strongly correlated with growing season length and cumulative degree days recorded near each population location. These latter data indicated that M. vimineum, introduced into this region <100 years ago, may be undergoing adaptive evolution. Although additional populations of M. vimineum need to be examined, this study suggests that local evolutionary adaptation may be occurring rapidly and could, potentially, be an important aspect in the establishment and spread of this invasive species.     

Histopathology provides a phenotype by which to characterize stripe rust resistance genes in wheat

The expression of the resistance phenotypes of QPst.jic‐2D and QPst.jic‐4B, two quantitative trait loci (QTL) for stripe rust resistance in wheat cv. Alcedo, were assessed relative to plant growth stage, while a histopathology analysis was undertaken to characterize the cellular interaction between Puccinia striiformis f. sp. tritici (the causal agent of stripe rust) and each QTL. QPst.jic‐2D expressed a partial resistant phenotype at seedling growth stages, with the level of resistance increasing as the wheat plant matured, conferring a disease‐free phenotype at heading. QPst.jic‐4B, however, did not express a resistant phenotype until booting (growth stage 41 on the Zadoks scale), displaying its full resistant phenotype at heading. Microscopic examination in flag leaves showed that infection sites formed in all genotypes tested, with full infection‐site establishment being observed by 36 h post‐inoculation (hpi). In lines carrying both QPst.jic‐2D and QPst.jic‐4B, as well as the parental cv. Alcedo, no microcolony formation, defined by the appearance of runner hyphae, was observed. Microcolony formation was observed in lines carrying only one, or neither QTL. Cell death associated with infection sites was observed for all genotypes, although the timing of first appearance and the extent of the cell death response varied considerably. In lines carrying both QPst.jic‐2D and QPst.jic‐4B cell death did not extend beyond one to three cells. In lines carrying only one QTL more extensive cell death was observed and cell death appeared later in lines with QPst.jic‐4B than QPst.jic‐2D. Cell death was also occasionally observed in lines without either QTL, although only at 264 hpi.     

Pyrethroid resistance discovered in a major agricultural pest in southern Australia: the redlegged earth mite Halotydeus destructor (Acari: Penthaleidae)

BACKGROUND: The redlegged earth mite (Halotydeus destructor Tucker) is an important pest of field crops and pastures. Control of this pest relies heavily on chemicals, with few genuine alternatives presently available. Pesticide responses of H. destructor from the field with reported chemical control failures were compared with mites from susceptible 'control' populations. Toxicology bioassays were conducted on adult mites across multiple generations. RESULTS: Very high levels of resistance to two synthetic pyrethroids, bifenthrin and alpha-cypermethrin, were detected in this species for the first time. For bifenthrin, LC(50) estimates showed a difference in resistance of greater than 240 000-fold. Resistance to alpha-cypermethrin was almost 60 000-fold. This resistance was shown to be heritable, persisting after several generations of culturing. There was no evidence that resistance to organophosphorus chemicals had evolved, which is likely to be a direct consequence of the history of chemical applications these mites have experienced. CONCLUSION: These results highlight the need for more judicious management decisions in order to control pest species in a sustainable manner. The implications of these findings in regard to the management and future research of the redlegged earth mite are discussed.     

Factors affecting phytotoxic activity of allelochemicals in soil

Allelopathy is the inhibitory or stimulatory effect of a plant (donor) on other plants (receivers) through the chemicals released from the donor plant to the environment, mostly into the soil. These chemicals may reach the receiver plants in various ways, including leaching from plant foliage, exudation from the roots, and decomposition of dead residue of the donor plants. However, allelopathy in soil is a complicated phenomenon that is affected by soil condition, growth condition of the donor and receiver plants and climatic condition. Allelochemicals in soil are adsorbed on soil solids, and metabolized by chemical and biological reactions during the movement in soil. This behavior is affected by various soil factors, such as soil texture, organic and inorganic matter, moisture and organisms, which affect the phytotoxic activity in soil. If an allelochemical can directly affect the growth of receiver plants in soil, then the allelochemical might be present in the soil water so that it is directly available for absorption by the plant. Thus, it is suggested the concentration of an allelochemical in soil water is a dominant factor directly determining the phytotoxic activity in soil, and the concentration is controlled by soil factors that affect the behavior of adsorption, desorption and degradation in soil.     

United States Department of Agriculture-Agricultural Research Service research in application technology for pest management

A research summary is presented that emphasizes ARS achievements in application technology over the past 2-3 years. Research focused on the improvement of agricultural pesticide application is important from the standpoint of crop protection as well as environmental safety. Application technology research is being actively pursued within the ARS, with a primary focus on application system development, drift management, efficacy enhancement and remote sensing. Research on application systems has included sensor-controlled hooded sprayers, new approaches to direct chemical injection, and aerial electrostatic sprayers. For aerial application, great improvements in on-board flow controllers permit accurate field application of chemicals. Aircraft parameters such as boom position and spray release height are being altered to determine their effect on drift. Other drift management research has focused on testing of low-drift nozzles, evaluation of pulsed spray technologies and evaluation of drift control adjuvants. Research on the use of air curtain sprayers in orchards, air-assist sprayers for row crops and vegetables, and air deflectors on aircraft has documented improvements in application efficacy. Research has shown that the fate of applied chemicals is influenced by soil properties, and this has implications for herbicide efficacy and dissipation in the environment. Remote sensing systems are being used to target areas in the field where pests are present so that spray can be directed to only those areas. Soil and crop conditions influence propensity for weeds and insects to proliferate in any given field area. Research has indicated distinct field patterns favorable for weed growth and insect concentration, which can provide further assistance for targeted spraying.     

Cytospora oleina causing canker and dieback of olive in Greece

Cytospora oleina was isolated from dead twigs of olive associated with old cankers in the Mount Pelion region of central Greece. Inoculation of young trees with pure cultures of the fungus caused twig death in olive, especially when applied in autumn, and xylem discoloration in apple, plum, cherry, peach and apricot.     

苯并噁唑嗪酮类化合物的研究进展

苯并噁唑嗪酮化合物是禾本科作物中一类重要的植物次生代谢物,具有抗菌、抗虫、化感等重要生物活性,此类化合物的研究一直是近几年的热点。本文介绍了其在植物中的分布、结构、种类、生物合成、遗传性和生物活性。     

A survey for Bursaphelenchus spp. in pine forests in Norway

Wood samples from pine trees were taken from 429 sites throughout Norway. The samples were selected as being either from (1) healthy trees, (2) trees suffering from stress, either physical or pathological or (3) dead trees. Nematodes were recovered from 39% of samples, most from dead wood and least from healthy trees. Species of Bursaphelenchus were recovered from 12% of dead trees and 5% of stressed trees, but were never found in healthy wood. B. mucronatus was found at just one site and in this sample it was associated with Monochamus sutor , only one of two sites at which the beetle was detected. Based on the information gained from the survey and from other sources, an assessment is made of the risk of introduction of B. xylophilus from outside Europe on imported wood and its survival, spread and disease potential in European forests.