Phytotoxic activity of crop residues from Burdock and an active substance

Abstract

Problems related to weed management such as outbreaks of herbicide-resistant weeds have recently increased. An interesting approach to such problems is to use plant materials with phytotoxic activity. Burdock (Arctium lappa L.) is a biennial herb belonging to Asteraceae and is cultivated in several countries. The present study investigated the phytotoxic activity of burdock and its active substances. Extracts of both burdock leaves and roots inhibited the shoot and root growth of cress and barnyard grass, where the level of inhibition increased with increasing extract concentration. The leaf extracts had 2.0–2.5 times higher activity than the root extracts. Bioassay-guided separations of the leaf extracts led to isolation of a phytotoxic substance, onopordopicrin. Onopordopicrin significantly inhibited the shoot and root growth of cress and barnyard grass. The concentrations of the substance required for 50% growth inhibition were 0.27 and 0.26?mM for cress shoots and roots, respectively, and 1.86 and 0.35?mM for barnyard grass shoots and roots, respectively. The present results suggest that burdock leaves have high phytotoxic activity and onopordopicrin may play a major role in the activity. Burdock leaves may be a good resource for weed management.     

Quantitative analysis of pyrrolizidine alkaloids sequestered from diverse host plants in Longitarsus flea beetles (Coleoptera, Chrysomelidae)

Summary. Several species of the flea beetles genus Longitarsus are able to sequester pyrrolizidine alkaloids (PAs) from their host plants. In five Longitarsus species we compare the concentration of PAs present in their host plants belonging to the Asteraceae or Boraginaceae with those found in the beetles. To get an estimate of the intrapopulation variability, three samples of five beetles each and five individual plants were analyzed for each comparison. A strong intrapopulation variability could be detected both among plant and beetle samples. The total concentration found in the beetles varied strongly between species. The local host plant and its phenology influence the concentrations present in the beetles as evidenced in comparisons of a single beetle species from two different hosts and of one beetle species collected at the same site at different times of the year. In addition, different beetle species apparently vary in their capacity to sequester the alkaloids, at the lowest extreme the mean PA concentration in the beetles (0.034 μg PA/mg dry weight) was 1/30 of the mean concentration found in the plant leaves (L. aeruginosus from Eupatorium cannabinum), at the highest extreme (2.098 μg PA/mg dw) the concentration in the beetles was a 1000 fold higher than in the plant leaves (L. nasturtii from Symphytum officinale). The highest mean concentration found in the beetles was 3.446 μg/mg dw (L. exoletus from Cynoglossum officinale). The absolute concentrations found in the beetles are comparable to other insects which have been shown to be effectively defended against their potential predators. Received 22 June 1999; accepted 25 August 1999     

部分菊科入侵种种子(瘦果)的萌发能力和幼苗建群特性

对入侵种种子生物学各方面的了解有助于更好地预测入侵趋势和评估可持续管理的策略.研究通过对部分菊科入侵种种子(瘦果)进行的室内萌发实验和土壤埋藏实验,通过与相关研究的对比和分析,对这些入侵种的萌发能力和幼苗建群特性进行了研究.10个入侵种种子室内萌发实验的结果表明,在25℃、12h光照的情况下,除钻形紫菀和一年蓬以外,被研究的其它8个种的终萌发率超过了50%,而且都显示出早期快速萌发的特点.用SPSS的曲线拟合工具对10个种的累积萌发趋势进行了曲线回归分析,对应的最佳模型均为三次曲线方程.不同土壤埋藏深度下幼苗出苗实验的结果表明,菊科8个入侵种的种子在表土的出苗率均最高,随着覆土厚度的增加,种子的出苗率逐渐降低,当覆土厚度超过3 cm以上时,所有种子均不能出苗.种子在不同的埋藏深度的出苗情况与种子的大小有关,较大种子破土能力相对较强;种子在不同的埋藏深度的出苗情况与种子本身的萌发能力也相关.土壤埋藏期限的实验结果表明,随埋藏时期的增加,小蓬草、苏门白酒草和一年蓬3个人侵种种子的活力逐步降低,在土壤中埋藏12个月后,其活力分别为21.34%、18.15%和27.38%.这些入侵种较广的种子萌发温度适应范围和高萌发率为防除工作带来了困难.在生产上,可通过不同时期的翻耕、将种子深埋等措施减少这些入侵种的危害.     

三种菊科入侵植物的生长与化学防御的关系研究

“生活史理论”认为,植物可利用的资源总量是有限的,在植物的不同功能之间存在着此消彼长的权衡关系。入侵植物的生长和化学防御一般优于本地植物,那么其生长与化学防御之间是否存在权衡及其权衡关系怎样,目前尚不清楚。以广东省3种菊科入侵植物[三裂叶蟛蜞菊（Wedelia trilobata （L.） Hitchc.）、飞机草（Eupatorium odoratum）和薇甘菊（Mikania micrantha）]为研究对象,并分别以近缘或伴生的本地植物[蟛蜞菊（Wedelia chinenses）、华泽兰（Eupatorium chinense）和鸡矢藤（Paederia scandens）]为对照,研究入侵植物的生长特性（相对生长率和比叶面积）与化学防御物质（缩合单宁和总酚）含量,并基于这2种光合碳分配的主要形式,探讨入侵植物生长与化学防御之间的权衡关系。结果表明：3种入侵植物的相对生长率均高于本地对照种;薇甘菊的比叶面积大于对照种,而其他2种无明显优势。薇甘菊和三裂叶蟛蜞菊的缩合单宁显著高于对照种,飞机草的总酚含量高于对照种。我们的结果显示,入侵植物的生长和化学防御均优于本地植物,但它们的碳同化能力相近;因此,入侵植物特殊的内在资源分配与利用机制可能是其成功入侵的关键。     

Sequestration of plant pyrrolizidine alkaloids by chrysomelid beetles and selective transfer into the defensive secretions

Summary Oreina cacaliae andO. speciosissima (Coleoptera, Chrysomelidae) sequester in their elytral and pronotal defensive secretions pyrrolizidine alkaloids (PAs) as Noxides (PA N-oxides). The PA N-oxide patterns found in the beetles and their host plants were evaluated qualitatively and quantitatively by capillary gas chromatography/mass spectrometry (GC-MS). Of the three host plantsAdenostyles alliariae (Asteraceae) is the exclusive source for PA N-oxide sequestration in the defensive secretions of the beetles. With the exception of O-acetylseneciphylline the N-oxides of all PAs ofA. alliariae, i.e. senecionine, seneciphylline, spartioidine, integerrimine, platyphylline and neoplatyphylline were identified in the secretion. PA N-oxides typical ofSenecio fuchsii (Asteraceae) were detected in the bodies of the beetles but not in their secretion. No PAs were found in the leaves of the third host plant,Petasites paradoxus (Asteraceae). The results suggest the existence of two distinctive storage compartments for PA N-oxides in the beetle: (1) the defensive secretion, containing specifically PA N-oxides acquired fromA. alliariae; (2) the body of the beetle, sequestering additionally but less selectively PA N-oxides from other sources,e.g. S. fuchsii or monocrotaline N-oxide fed in the laboratory. The concentration of PA N-oxides in the defensive secretion is in the range of 0.1 to 0.3 mol/1, which is more than 2.5 orders of magnitude higher than that found in the body of the beetle. No significant differences exist in the ability of the two species of beetles to sequester PA N-oxides fromA. alliariae, althoughO. speciosissima, but notO. cacaliae, produces autogenous cardenolides. A negative correlation seems to exist between the concentrations of plant-derived PA N-oxides andde novo synthesized cardenolides in the defensive secretion ofO. speciosissima.     

<Emphasis Type="Italic">Ceroplastes albolineatus</Emphasis>, the first scale insect shown to sequester pyrrolizidine alkaloids from its host-plant <Emphasis Type="Italic">Pittocaulon praecox</Emphasis>

Summary. The occurrence of pyrrolizidine alkaloids (PAs) in Pittocaulon (ex Senecio) praecox (Asteraceae) a species endemic to Mexico was established. The aboveground plant organs contain the 1,2-saturated monoester 7-angeloyl-dihydroxyheliotridane together with a small proportion of its 9-angeloyl isomer as major alkaloid. The monoesters are accompanied by the macrocyclic otonecine derivative senkirkine. Roots contain only related macrocyclic PAs with senecionine, senkirkine and platyphylline as major components; monoesters are absent. The broom-like succulent stems of P. praecox are infested by the scale insect Ceroplastes albolineatus conspicuously visible by its huge wax cover. All life-history stages, i.e. females, eggs, first instar nymphs (crawlers) and the wax cover were found associated with PAs. The measured PA concentrations clearly indicate sequestration. The highest PA concentrations (mg / g dry weight) reached are: mature females, 0.44; eggs, 0.58; crawlers, 0.37; wax cover, 0.08. The host plant as well as in the infesting scale insect contain the PAs exclusively as free bases. As a phloem-feeder C. albolineatus must acquire the PAs with the ingested phloem sap. This appears plausible since in Senecio species PA are transmitted and circulated through the phloem path. It is suggested that PAs may protect particularly the crawlers as the most endangered stage in the life-cycle of the scale insect.     

Pyrrolizidine alkaloids between plants and insects: A new chapter of an old story

Summary Among alkaloids the pyrrolizidine alkaloids (PAs) play a unique role in the interactions between plants and adapted insects. InSenecio spp. (Asteraceae) PAs are synthesized in the roots as alkaloidN-oxides which are specifically translocated into shootsvia the phloem-path and channeled to the preferred sites of storage (e.g. inflorescences) where they are stored in the cell vacuoles. In differentSenecio spp. senecionineN-oxide is produced as the common product of biosynthesis, which subsequentlyvia a number of simple but specific reactions is transformed into typical speciesspecific PA-patterns. Insects from diverse taxa sequester PAs for their own defense. Lepidopterans (e.g. arctiids such asTyria jacobaeae andCreatonotos transiens) may hydrolyze plant acquired ester-PAs and convert the resulting necine base into insect-specific PAs by esterification with an acid of their own metabolism. Adapted arctiids and the grasshopperZonocerus take up PAs in the state of the tertiary amine.N-Oxides are reduced in the guts prior to uptake. In the bodies the tertiary PAs are rapidlyN-oxidized by a specific mixed-function oxigenase and are maintained in theN-oxide state. The importance of the reversible interconversion of the nontoxicN-oxide (pro-toxine) into the toxic tertiary alkaloid is discussed as the specific feature of PAs in plant-insect interactions.     

Plant volatiles are behavioral cues for adult females of the gall wasp Antistrophus rufus

Summary. The purpose of this study was to identify plant volatiles that provide host location cues for adult females of the gall wasp Antistrophus rufus Gillette (Hymenoptera: Cynipidae). Larvae of this species inhabit flowering stems of the prairie perennial Silphium laciniatum L. (Asteraceae). Adult females responded to volatile compounds emitted by stems of S. laciniatum in field olfactometer bioassays. Plant volatiles were monoterpenes, including, in descending order of abundance, racemic - and -pinene (~50% + enantiomer for both), (+)-limonene, (–)-camphene, and -myrcene. In laboratory bioassays, females responded to aeration extracts of plant stems, the full blend of synthetic monoterpenes, and the four-component blend of -pinene, -pinene, (+)-limonene, and (–)-camphene. This monoterpene blend apparently serves as an olfactory cue for host plant location for female A. rufus and is the first such cue to be reported for a cynipid gall wasp. Species-specific ratios of plant monoterpenes may provide cues for gall wasp females to distinguish between plant species and choose appropriate hosts for oviposition. The olfactometer and bioassay techniques developed for this research may be useful for field bioassays of other types of minute arthropods.     

加拿大一枝黄花有性生殖特征研究

加拿大一枝黄花Solidago canadensis L.是分布于我国的危害性最为严重的入侵种之一,它既可以通过有性生殖又可以通过无性生殖进行繁殖.对加拿大一枝黄花有性生殖的相关特征,如花序和小花的生物学特性、结实率和传粉方式等进行了研究.结果表明,加拿大一枝黄花的性系统为雌全性系统,每花序总花数为(15.16±1.67)个,缘花/盘花值为3.07±0.64.对成熟果实透明后进行的结实率统计表明,其结实率较低.套纱布网袋后的结实率极显著低于开放性授粉的,表明其花序是需要昆虫传粉的类型.加拿大一枝黄花的花序结构特征和开放式样显示出有利于增加异交的特点.尽管其结实率相对较低,但整个植株结实量大,仍需要防止其通过有性生殖产生的种子进行远距离的扩散和在新分布地区建立种群. 花有性生殖的相关特征,如花序和小花的生物学特性、结实率和传粉方式等进行了研究.结果表明,加拿大一枝黄花的性系统为雌全性系统,每花序总花数为(15.16±1.67)个,缘花/盘花值为3.07±0.64.对成熟果实透明后进行的结实率统计表明,其结实率较低.套纱布网袋后的结实率极显著低于开放性授粉的,表明其花序是需要昆虫传粉的类型.加拿大一枝黄花的花序结 特征和开放式样显示出有利于增加异交的特点.尽管其结实率相对较低,但整个植株结实量大,仍需要防止其通过有性生殖产生的种子进行远距离的扩散和在新分布地区建立种群. 花有性生殖的相关特征,如花序和小花的生物学     

Fungicidal Activity of Artemisia herba alba Asso (Asteraceae)

The antifungal activity of Artemisia herba alba was found to be associated with two major volatile compounds isolated from the fresh leaves of the plant. Carvone and piperitone were isolated and identified by GC/MS, GC/IR, and NMR spectroscopy. Antifungal activity was measured against Penicillium citrinum (ATCC 10499) and Mucora rouxii (ATCC 24905). The antifungal activity (IC₅₀) of the purified compounds was estimated to be 5 μ g/ml, 2 μ g/ml against Penicillium citrinum and 7 μ g/ml, 1.5 μ g/ml against Mucora rouxii carvone and piperitone, respectively.