Screening of phytotoxicity of Alternaria macrospora MKP1 against Parthenium hysterophorus L.

Parthenium hysterophorus L. an exotic, pernicious weed is considered as one of the most troublesome weeds for agricultural sector by virtue of its high ecological amplitude and adaptability. Microbes and their by-products are now proved to be a worthy alternative to toxic chemicals used for weed management. Alternaria macrospora MKPI was isolated from the parthenium leaves infected with leaf blight and found pathogenic to the weed. The herbicidal potential of cell free culture filtrate of A. macrospora MKP1 has been tested against parthenium by employing detached leaf bioassay and seed germination bioassay and a significant damage was exhibited by the cultural filtrate of pathogen to the parthenium leaves and seeds.     

Occurrence of hysterin and dihydroisoparthenin in Parthenium hysterophorus

Two sesquiterpene lactones, hysterin and dihydroisoparthenin, have been identified in Parthenium hysterophorus from Argentina and Jamaica by TLC and NMR.     

Sesquiterpene lactone variability in Parthenium hysterophorus L

A population of Parthenium hysterophorus collected in Salta Argentina afforded two ambrosanolides, 2beta-hydroxycoronopilin and 1alpha,2beta,4beta-trihydroxypseudoguaian-6beta,12-olide, as well as five known others. Plants of the fructification from those transplanted from the Puna Argentina at 1200 m over the sea level produced hymenin.     

Phenological behaviour of Parthenium hysterophorus in response to climatic variations according to the extended BBCH scale

Considering the importance of ecological and biological traits in imparting invasive success to the alien species, the phenological behaviour of an alien invasive weed Parthenium hysterophorus was documented according to the extended BBCH scale in four different seasons. A phenological calendar was prepared using both two‐ and three‐ digit coding system, precisely describing the developmental stages of the weed. The phenological documentation is further supplemented with the dates corresponding to a particular growth stage, pictures of the representative growth stages and meteorological data of all the four seasons. Results revealed that the phenology of the weed altered in response to the changing temperature and humidity conditions but no apparent climatic condition could inhibit its germination or flowering. However, the emergence of inflorescence was highly sensitive to the temperature/photoperiodic conditions. Variations in the phenological traits of P. hysterophorus with changing environmental conditions explain the acclimatisation potential of the weed permitting its vast spread in the non‐native regions. Since the given phenological illustrations are accurate, unambiguous and coded as per an internationally recognised scale, they could be exploited for agronomic practices, weed management programmes, and research purposes.     

Biogeographical variation in community response to root allelochemistry: novel weapons and exotic invasion

Centaurea diffusa is one of the most destructive invasive weeds in the western USA and allelopathy appears to contribute to its invasiveness ( Callaway & Aschehoug 2000 ). Here we identify a chemical from the root exudates of C. diffusa, 8‐hydroxyquinoline, not previously reported as a natural product, and find that it varies biogeographically in its natural concentration and its effect as an allelochemical. 8‐Hydroxyquinoline is at least three times more concentrated in C. diffusa‐invaded North American soils than in this weed's native Eurasian soils and has stronger phytotoxic effects on grass species from North America than on grass species from Eurasia. Furthermore, experimental communities built from North American plant species are far more susceptible to invasion by C. diffusa than communities built from Eurasian species, regardless of the biogeographical origin of the soil biota. Sterilization of North American soils suppressed C. diffusa more than sterilization of Eurasian soils, indicating that North American soil biota may also promote invasion by C. diffusa. Eurasian plants and soil microbes may have evolved natural resistance to 8‐hydroxyquinoline while North American plants have not, suggesting a remarkable potential for evolutionary compatibility and homeostasis among plants within natural communities and a mechanism by which exotic weeds destroy these communities.     

Trichome studies in Parthenium hysterophorus and their taxonomic importance

In Parthenium hysterophorus L. four trichome types i.e. (1) cylindrical hair, (2) moniliform hair, (3) simple multiseriate hair and (4) shaggy hair, have been recognized mostly on the basis of their structural differences. In the past, these types have not been observed in any species of Parthenium studied so far. Out of these four, two types i.e. cylindrical and moniliform hairs are known to occur in the Compositae and remaining two i.e. simple multiseriate and shaggy hairs are the new forms for the family and have been observed for the first time in presently investigated species. Trichomes are an important taxonomic tool in distinguishing between genera and species. Trichomes of the different species of Parthenium as noticed from their structure are useful in distinguishing these species and even their corresponding organs.     

Aerobiology and some chemical parameters of Parthenium hysterophorus pollen

Parthenium hysterophorus, a recently invaded toxic weed, in Eastern India, is now growing gregariously in Salt Lake City — a newly developed township situated in the eastern fringe of the metropolitan city of Calcutta. The floristic survey revealed that most of the trees and shrubs in Salt Lake City have been introduced except for a few, which were recorded as natural occurrence, Parthenium being most prevalent among them. Ecological associations of Parthenium in various localities of Salt Lake City were also investigated. Aerobiological survey was done using a Burkard seven day Volumetric Spore Trap, with the object to record the occurrence of Parthenium pollen in the air of Salt Lake in different seasons along with other airborne types. A total of 45 pollen and 60 fungal spore types were trapped and recorded. The frequency of grass and cyperaceous pollen were found to be dominant followed by Trema. Frequency of Parthenium was relatively insignificant. Chemical analyses of the pollen grains of Parthenium including assay of carbohydrate, lipid, protein, etc., were done. Clinically one out of six patients showed ELISA positive reaction to Parthenium pollen.     

Acetylated pseudoguaianolides from Parthenium hysterophorus and their cytotoxic activity

Chemical examination of the flowers of Parthenium hysterophorus has resulted in the isolation of four acetylated pseudoguaianolides along with several known constituents. The structures of the compounds were derived from detailed studies of their spectral (1D and 2D NMR and FABMS) data and by comparison of the values with those of parthenin, a major known constituent of the plant. The cytotoxic activity of parthenin and the constituents was evaluated using Jurkat (human: T lymphocyte; acute T cell leukemia), HL-60 (human leukemia) and Hela (human cervical carcinoma) cells.     

银胶菊(Parthenium hysterophorus)中抗TMV活性成分的分离及活性测定

采用活性跟踪法从银胶菊中分离获得抗病毒活性物质,经质谱和核磁共振分析,确定该物质为小白菊内酯.采用半叶枯斑法和叶圆盘法测定了其对烟草花叶病毒(Tobacco mosaic virus,TMV)的抑制效果,结果表明:0.2 mg/mL的小白菊内酯在混合接种和药液浸泡两种处理中均表现出较好的体外抑制TMV活性,其抑制率分别为69.0%和72.1%;在离体条件下对烟草叶圆盘中的烟草花叶病毒复制也具有良好的抑制效果,抑制率为72.3%.     

Germination ecology of the weed Parthenium hysterophorus in eastern Ethiopia

Germination ecology of Parthenium hysterophorus, recently introduced to Ethiopia, was studied in a series of experiments. Viability of the seeds was greater than 50% after 26 months of burial in the soil indicating the potential build‐up of a substantial persistent soil seed bank. A short period of dry storage was sufficient to overcome a light requirement for germination in a minor fraction of the seeds. Likewise, seeds exhumed from burial showed an increase in germination ability in darkness over time, with a weak tendency for seasonal cyclicity in dormancy level at one of two sites. Germination occurred at the mean minimum (10°C) and maximum (25°C) temperatures of the collection sites, as well as over a wide range of fluctuating (12/2°C‐35/25°C) temperatures in light. No germination of P. hysterophorus seeds occurred at osmotic potentials < ‐0.52 MPa (at 27°C), the species being less tolerant to moisture stress than sorghum grains. Most seedlings emerged from shallowly buried (< 0.5 cm) seeds and none from more than 5 cm depth. Naturally dispersed seeds required about 60 days, at a hot lowland site, to start emergence despite the presence of adequate rainfall, and higher number of seedlings emerged in undisturbed plots than in hand hoed plots. These experiments and field observations suggest that there are no obvious climatic conditions that may limit the germination of Parthenium hysterophorus in Ethiopia, but a high moisture requirement of the seeds for germination could be the major factor limiting germination during the dry season.     

Distributions of invasive weed Parthenium (Parthenium hysterophorus L.) in the University campus Peshawar KPK

A very interesting survey was performed to measure the distribution of invasive Parthenium (Parthenium hysterophorus L.) weed in the University Campus, Peshawar, the capital city of Khyber Pakhtunkhwa province. The University Campus comprised on; The University of Peshawar, Islamia College University, The University of Agriculture Peshawar, Pakistan Forest Institute and the New Developmental Research Farm. In these selected areas Parthenium weed distribution was measured in particular the academic, residential and research farm. Moreover, the survey also investigated the impact of parthenium weed upon native weeds flora inside the University campus. A 1m² quadrat was used to collect the data. During the survey, a total of 32 weeds species were recorded belonging to 18 different families and 32 genera, the life cycle of 23 weeds were annual while 9 weeds have a perennial. The data were recorded on absolute density (%), relative density (%), absolute frequency (%), relative frequency (%) and importance values (%) of parthenium weed and others flora. The collected data show that parthenium weed was the most dominant species having 76.8 m^?2 plants density in the NDF and (32.0 m^?2) at Islamia College University. However, the highest frequency (100%) of Parthenium was observed for The University of Agriculture, while minimum (80%) occurred in the Agronomy field. A More, the relative frequency of Parthenium was maximum (25%) in Islamia College; whereas, it's minimum (12.9%) at Agronomy field. Finally, the Importance Value of Parthenium indicates the highest (45.98%) at Dairy Farm followed by (40.33%) at the Horticulture field's area. In short, the Parthenium weed becomes more problematic and replaces all the native flora in the non-crop area specially Dicanthium annulatum L. a native grass species on the ridges of the field being replaced by parthenium. Due to no proper management and high growth rate, nowadays it becomes like a superweed in the KPK and especially in Pakistan. So, the management of Parthenium weed requires the call attention from the Govt. policymaker and proper quarantine inspection to conserve the native flora and field crops to get maximum crop yield.     

Dispersal response to climate change: scaling down to intraspecific variation

Range shift, a widespread response to climate change, will depend on species abilities to withstand warmer climates. However, these abilities may vary within species and such intraspecific variation can strongly impact species responses to climate change. Facing warmer climates, individuals should disperse according to their thermal optimum with consequences for species range shifts. Here, we studied individual dispersal of a reptile in response to climate warming and preferred temperature using a semi‐natural warming experiment. Individuals with low preferred temperatures dispersed more from warmer semi‐natural habitats, whereas individuals with higher preferred temperatures dispersed more from cooler habitats. These dispersal decisions partly matched phenotype‐dependent survival rates in the different thermal habitats, suggesting adaptive dispersal decisions. This process should result into a spatial segregation of thermal phenotypes along species moving ranges which should facilitate local adaptation to warming climates. We therefore call for range shift models including intraspecific variation in thermal phenotype and dispersal decision.     

Selective herbivory by Christmas beetles in response to intraspecific variation in Eucalyptus terpenoids

Between-tree variation in the terpenoid composition in the foliage of six species of Eucalyptus was investigated in relation to its effects on herbivory by Christmas beetles (Anoplognathus spp.). All six eucalypt species showed considerable intraspecific variation in terpenoid composition; the cineole content ranged from 13% to 78% of the total oil in different E. melliodora trees, from 0% to 67% in E. conica, 3% to 79% in E. sideroxylon, 1% to 76% in E. camaldulensis, 3% to 60% in E. rubida and 20% to 79% in E. blakelyi. Levels of defoliation by Christmas beetles of nine E. melliodora and eight E. conica trees were quantified from frass traps placed under each tree, and were used to confirm the reliability of visual ratings of defoliation. Defoliation was assessed visually for all six species and was found to be unrelated to the total amount of terpenoids in the foliage of each tree, but strongly associated with the percentage of cineole in the terpenoid mixture. Levels of most terpenoid components were significantly inter-correlated, so it was not possible to determine which components directly affected defoliation. The dominant Christmas beetle at all sites was A. montanus.     

Evaluation of Alternaria alternata ITCC4896 for use as mycoherbicide to control Parthenium hysterophorus

Mycoherbicides are specialty biotechnology products which employ the use of fungi or fungal metabolites as non-chemical alternatives, thereby reducing the input of harmful chemicals to control noxious weeds. The present communication emphasises the potential of an indigenous isolate of Alternaria alternata ITCC 4896 as a mycoherbicide for the global weed Parthenium hysterophorus. Of the various spore concentrations tested by in vitro detached leaf bioassay, 1 × 10⁶ spores/ml was the most effective, inducing 89.2% leaf area damage on the seventh day and was further tested by the whole plant bioassay. Both in vitro detached leaf assay and whole plant bioassay exhibited a similar trend in disease development, exhibiting 50% damage at 96 hours post-treatment. However, 100% mortality was observed in the whole plant bioassay on the seventh day. This is the very first report on the bioweedicidal potential of Alternaria alternata ITCC 4896 (LC#508) for use as a mycoherbicide for Parthenium hysterophorus.     

The Invasive American Weed Parthenium hysterophorus Can Negatively Impact Malaria Control in Africa

The direct negative effects of invasive plant species on agriculture and biodiversity are well known, but their indirect effects on human health, and particularly their interactions with disease-transmitting vectors, remains poorly explored. This study sought to investigate the impact of the invasive Neotropical weed Parthenium hysterophorus and its toxins on the survival and energy reserves of the malaria vector Anopheles gambiae. In this study, we compared the fitness of An. gambiae fed on three differentially attractive mosquito host plants and their major toxins; the highly aggressive invasive Neotropical weed Parthenium hysterophorus (Asteraceae) in East Africa and two other adapted weeds, Ricinus communis (Euphorbiaceae) and Bidens pilosa (Asteraceae). Our results showed that female An. gambiae fitness varied with host plants as females survived better and accumulated substantial energy reserves when fed on P. hysterophorus and R. communis compared to B. pilosa. Females tolerated parthenin and 1-phenylhepta-1, 3, 5-triyne, the toxins produced by P. hysterophorus and B. pilosa, respectively, but not ricinine produced by R. communis. Given that invasive plants like P. hysterophorus can suppress or even replace less competitive species that might be less suitable host-plants for arthropod disease vectors, the spread of invasive plants could lead to higher disease transmission. Parthenium hysterophorus represents a possible indirect effect of invasive plants on human health, which underpins the need to include an additional health dimension in risk-analysis modelling for invasive plants.     

Molecular profiling of rhizosphere bacterial communities associated with Prosopis juliflora and Parthenium hysterophorus

Prosopis juliflora and Parthenium hysterophorus are the two arid, exotic weeds of India that are characterized by distinct, profuse growth even in nutritionally poor soils and environmentally stressed conditions. Owing to the exceptional growth nature of these two plants, they are believed to harbor some novel bacterial communities with wide adaptability in their rhizosphere. Hence, in the present study, the bacterial communities associated with the rhizosphere of Prosopis and Parthenium were characterized by clonal 16S rRNA gene sequence analysis. The culturable microbial counts in the rhizosphere of these two plants were higher than bulk soils, possibly influenced by the root exudates of these two plants. The phylogenetic analysis of V1_V2 domains of the 16S rRNA gene indicated a wider range of bacterial communities present in the rhizosphere of these two plants than in bulk soils and the predominant genera included Acidobacteria, Gammaproteobacteria, and Bacteriodetes in the rhizosphere of Prosopis, and Acidobacteria, Betaproteobacteria, and Nitrospirae in the Parthenium rhizosphere. The diversity of bacterial communities was more pronounced in the Parthenium rhizosphere than in the Prosopis rhizosphere. This culture-independent bacterial analysis offered extensive possibilities of unraveling novel microbes in the rhizospheres of Prosopis and Parthenium with genes for diverse functions, which could be exploited for nutrient transformation and stress tolerance in cultivated crops.     

入侵植物银胶菊在不同生境下表型可塑性和构件生物量

研究了入侵植物银胶菊在4种不同小生境间花果期形态特征变化和构件生物量特征。结果显示:在植株密度小但土壤肥沃的小生境中,植株各形态指标如茎长、茎直径和花序直径等都明显高于其它小生境,在生物量结构特征上则表现为总生物量和花果生物量所占比例的升高。随着植株密度的增加以及土壤肥力下降,上述各形态指标都发生了较明显的变化,生物量投资也进行了优化配置,银胶菊表现出了较高的形态可塑性。银胶菊与觅光和竞争相关的几个指标如叶和根的比例都增加,但用于生殖构件的比例却减少了。相关分析显示,银胶菊花果期各构件生物量与高度成正相关,与密度为负相关,并受环境因素的制约。表明,较高的形态可塑性和较强的生殖配置策略可能是银胶菊成功入侵我国的重要特征。     

Correction to: Invasion status and impacts of parthenium weed (Parthenium hysterophorus) in West-Central region of Bhutan

Biological Invasions - A correction to this paper has been published: https://doi.org/10.1007/s10530-021-02573-w     

Invasion status and impacts of parthenium weed (Parthenium hysterophorus) in West-Central region of Bhutan

Parthenium weed (Parthenium hysterophorus L.) is an invasive alien plant species that is spreading rapidly all over the world. With globalization and climate change, it will continue to spread, posing threats to agriculture, biodiversity and the environment. To determine its invasion and impacts in Bhutan, an investigation was undertaken in West-Central Bhutan using a questionnaire survey, complemented by MaxEnt modelling. Most farmers (19–30%) recall having seen parthenium for the last 11–15 years, or more. Infestations of parthenium differed significantly (P?<?0.05) across three districts for dryland, orchards, fallow land and pastures, but not in rice fields and on roadsides. The most intensely invaded land types were fallow land, pastures, and roadsides, with farmers perceiving it as ‘somewhat common’(score?~?3) and ‘common’ (score?~?4) weed. Farmers’ perceptions of the invasiveness of parthenium weed were high at 77% (Wangdue), 80% (Punakha), and 88% (Tsirang), considering it as at least ‘somewhat invasive’, or higher. Only 13–25% of respondents scored the weed as ‘highly invasive’. Parthenium invasion significantly (P?<?0.01 to 0.001) escalated the cost of production, reduced fodder quality, supressed native species and caused allergies to the locals in the study districts. Further, MaxEnt modelling of parthenium distribution was undertaken, using the parthenium presence-only data and bioclimatic variables, under 2 CO₂ emission scenarios of the Intergovernmental Panel on Climate Change (IPCC), i.e. Representative Concentration Pathways (RCP2.6 and 8.5). The projections showed discernible spatial changes in climate suitability over 2070, mostly in the mid- and high-altitude zones, indicating aggressive incursion into Bhutan’s important agro-ecological landscapes. The findings, highlight the urgent need to initiate parthenium management strategies for food production and natural resources.