Search Results (43)

Botanical gardens have historically introduced alien species for agronomic, medicinal, and ornamental purposes, but they also contribute to plant invasions. The Hortus Botanicus Karalitanus (HBK) is a historic botanical garden established in 1866, as an acclimatisation arboretum for tropical plants, by the University of Cagliari. This study inventoried alien vascular plants in the HBK that showed some degree of spontaneity, analysing their status, origin, life form, introduction pathways, reproductive strategies, and presence in Sardinian habitats. A focus on invasive species and their historical introduction based on their first records on the island and in the HBK was made. Field surveys from 2015 to 2024 allowed us to identify 146 alien taxa, primarily neophytes (83%), 45% of which were naturalised and 12% were invasive. Ornamental plants contributed to 70% of introductions, while accidental taxa (weeds and hitchhikers, 61%) were the most invasive. Seed reproduction was the most common way of propagation (41%). About the diffusion in Sardinia, 25% of taxa had no records in nature outside the HBK, 39% were found only in anthropogenic habitats, and 36% in natural habitats. Among them, 8% were invasive in both the HBK and Sardinia, with wetlands being the most affected (5%). However, only 3% of common invasive species were first recorded in the HBK. The results highlight the role of the HBK in alien species spread and early detection, aiding in invasion management and biodiversity conservation in Sardinia. Full article

In Nigeria, Chromolaena odorata poses significant threats to agriculture by disrupting ecosystem structure and function, thereby altering ecosystem services. However, our understanding of its impact, potential uses, and control measures, particularly from the perspective of local communities who interact directly with the plant, presents opportunities for a balanced approach to sustainable management. The aim of this study was to document the knowledge and perceptions of the introduction and spread of C. odorata, its ethnopharmacological applications, and its effects on crops, livestock, and wildlife, as well as discuss control strategies. Using participatory rural appraisal techniques, we administered semi-structured questionnaires to 150 respondents across six villages in Edo State, Nigeria. The findings reveal that C. odorata is a well-recognized invasive species that has been present for several decades and is commonly referred to by its local name, “Awolowo weed”. Although many respondents were unsure of the reasons behind its introduction, most were familiar with its mode of dispersal. A significant proportion of respondents view the weed as a serious threat to agriculture and a major hindrance to human movement by foot to and from their farmlands where C odorata is dominant. However, many also reported its relative ease of management. Interestingly, 92.7% acknowledged the medicinal value of C. odorata, citing its use in treating fever, wounds, and stomach aches, while 84% reported its ability to enhance soil fertility. Most respondents did not perceive the plant as harmful to livestock or wildlife. Though many believe that the plant has continued to spread, 83.8% oppose its complete eradication. Instead, they highlighted Elephant grass (Pennisetum purpureum Schumach) as a more problematic weed that requires immediate intervention. In summary, exploring the local benefits of C. odorata highlights the importance of leveraging local knowledge and practices to develop a robust, integrated approach for its sustainable long-term management. Full article

Parthenium weed (Parthenium hysterophorus L.) is one of the most noxious and fast-spreading invasive alien species, posing a major threat to ecosystems, agriculture, and public health worldwide. Mechanistic and correlative species distribution models are commonly employed to determine the potential habitat suitability of parthenium weed. However, a comparative analysis of these two approaches for parthenium weed is lacking, leaving a gap in understanding their relative effectiveness and ability to describe habitat suitability of parthenium weed. This study compared the mechanistic model CLIMEX with random forest (RF), the best-performing of a suite of correlative models. When compared against occurrence records and pseudo-absences, measured by area under the receiver operating characteristic curve, true skill statistic, sensitivity, and specificity, the results revealed higher performance of RF compared to CLIMEX. Globally, RF predicted 7 million km² (2% of the total land mass) as suitable for parthenium weed, while CLIMEX predicted 20 million km² (13%). Based on binary maps, RF and CLIMEX identified 67 and 20 countries as suitable, respectively. For Bhutan, globally trained RF predicted 8919 km² (23% of the country’s total 38,394 km²) as currently suitable, with high suitability in the southern, west–central, central, and eastern districts, particularly along major highways. For the future, the 10 general circulation models downscaled to Bhutan showed a decrease in suitability across four scenarios (SSP126, SSP245, SSP370, SSP585) and three periods (2021–2050, 2051–2080, 2071–2100), with a northward shift in suitable habitats ranging from 2 to 76 km. Additionally, 2049 (23%) km² of agricultural land is currently at risk of being invaded by parthenium weed. Correlative and mechanistic models are based on different niche concepts (i.e., realized and fundamental, respectively), and therefore combining them can provide a better understanding of actual and potential species distributions. Given the high suitability of parthenium weed under the current climate and its potential negative impacts in Bhutan, early action such as early detection and control of infested areas, regular survey and monitoring, and creating public awareness are proposed as risk mitigation strategies. Full article

Mikania micrantha (“mile-a-minute” weed) is a global invasive alien weed that can cause severe damage to agroforestry ecosystems and significant agricultural losses worldwide. Although chemical, manual, or mechanical control methods are widely used to control M. micrantha, RNA interference (RNAi)-based biocontrol methods have rarely been reported for this species. The MONOPTEROS (MP) gene, encoding an auxin response factor, plays an essential role in embryonic root initiation in Arabidopsis thaliana. In this study, we identified the MP gene from M. micrantha via orthologous gene analysis. A total of 37 MP orthologous genes was identified in 4 plants, including 9 MP candidate genes in M. micrantha, 13 in Helianthus annuus, 6 in Chrysanthemum nankingense, and 9 in Lactuca sativa. Phylogenetic analysis revealed that an MP candidate gene in M. micrantha (Mm01G000655, named MmMP) was clustered into one clade with the MP gene in A. thaliana (AtMP). In addition, both MmMP and AtMP contain a B3-DNA binding domain that is shared by transcription factors that regulate plant embryogenesis. To study gene function, dsRNA against MmMP (dsMmMP) was applied to the roots of M. micrantha. Compared with those of the controls, the expression of MmMP was reduced by 43.3%, 22.1%, and 26.2% on the first, third, and fifth days after dsMmMP treatment, respectively. The dsMmMP-treated plants presented several morphological defects, mostly in the roots. Compared with water-treated plants, the dsMmMP-treated plants presented reduced developmental parameters, including root length, number of adventitious roots, root fresh and dry weights, plant height, and aboveground biomass. Additionally, safety assessment suggested that this dsMmMP treatment did not silence MP genes from non-target plants, including rice and tomato; nor did it inhibit root growth in those species. Collectively, these results suggest that MmMP plays an important role in root development in M. micrantha and provides a potential target for the development of species-specific RNAi-based herbicides. Full article

Argemone ochroleuca Sweet is an alien invasive weed dominating most cultivated lands, however, the phytochemicals present in this plant and the effects of these on the germination and growth of economically important crops such as maize are not well-documented. The objective of the study was to characterize the phytochemistry of the shoots and roots of A. ochroleuca and determine whether the extracts could inhibit the germination of maize seeds. The shoots and roots of A. ochroleuca were extracted in water, hexane, and acetone. Ten maize seeds were used in the germination bioassay. A phytochemical analysis was conducted using gas chromatography-mass spectrometry (GC-MS). The effects of the A. ochroleuca water, hexane, or acetone extracts on maize seed germination were concentration and plant-part dependent. The highest reduction was recorded from the water extract with 82%. Identified compounds with high percentages in A. ochroleuca were 9,12-octadecadienoic acid (Z,Z) and 9,12,15-octadecatrienoic acid, (Z,Z,Z)-. The present study indicated that A. ochroleuca extracts suppress the germination of maize seeds, likely due to the presence of both the identified and potentially unidentified phytochemicals that were not detected by the selected method. There is, however, a need to establish the relationship between the phytochemical compounds and the enzymes responsible for germination. Full article

The Tibetan plateau, with complex and diverse ecosystems, is an important ecological security barrier to China. However, climate change and the spread of invasive plant species have imperiled the once pristine and diverse ecosystem of the region. To prevent the further spread and control of invasive plants, it is important to delineate the potential distribution patterns of alien invasive plants at the regional scale across Tibet and understand their responses to climate change. Galinsoga parviflora Cav., a member of the family Asteraceae, is an annual herbaceous plant distributed globally as an invasive weed and possesses characteristics that make it highly invasive, such as a strong ability to proliferate and disperse. The species is also known to have an allelopathic effect. There has been no report on the spatial distribution of G. parviflora in Tibet. Using field survey data, we investigated the risk of G. parviflora invasion and its impacts on the ecological safety of Tibet. We employed the MaxEnt model using the R language and SPSS software to optimize and select model parameters and data. We acquired various environmental variables along with current and future climate change scenarios (two carbon emission scenarios, SSP126 and SSP585, for the years 2050 and 2090) to predict the geographic distribution and potential risk areas in Tibet that G. parviflora can invade. The MaxEnt model accurately predicted the distribution of G. parviflora in Tibet with an average AUC of 0.985. The most suitable environmental conditions in which G. parviflora performed the best in Tibet included a mean annual temperature of 6.2–10.0 °C and an elevation range of 2672–3744 m above sea level. Our results indicate that low precipitation during the coldest quarter of the year (mean temperature −2–3 °C) was the most important variable predicting G. parviflora distribution. The results also showed that the species was hardly found when precipitation in the coldest quarter exceeded 155 mm. The current potential invasion risk areas for G. parviflora included the river valleys of central, southeastern, and eastern Tibet. With future climate change scenarios (i.e., SSP126, SSP585), the suitable habitats for G. parviflora distribution will likely shift to northwest regions from the southeast. Particularly under the highest carbon emission scenario (i.e., SSP585), the potential risk area expands more rapidly, and the center of distribution shifts to northwest regions. These findings provide useful information about the current and future changes in G. parviflora distribution in Tibet, which is crucial for the comprehensive and proactive management and control of G. parviflora under future climate change. Full article

Background: The hydrological effects of invasive plant control in forestland have not been well studied in the past, and numerous scientific mysteries remain unsolved. The long-term suspension of the unsolved issues will unavoidably influence the sound growth and sustainable management of forest ecosystems. This study investigates the hydrological effects of controlling invasive weeds in forestland. The research aims to understand the impact of invasive weed control on soil and water loss. Methods: Conducted in Eucalyptus benthamii Maiden & Cambage plantations in Central Yunnan, SW China, which are invaded by alien weed Ageratina adenophora (Spreng.) R. M. King & H. Rob., four surface cover treatments were applied to study runoff and sediment yielding properties. The four surface cover treatments were weed harvesting and litter elimination (WH&LE), weed harvesting and litter retention (WH&LR), litter burning and weed renewal (LB&WR), and weed retention and litter retention (WR&LR). Essentially, WH&LE and LB&WR served as integrated management approaches for invasive weeds and litter, WH&LR was an independent weed control measure, and WR&LR served as a research control. Results: Runoff was significantly higher in the LB&WR plots (3.03 mm) compared to the WR&LR plots (1.48 mm) (p < 0.05). The WH&LE plots had higher runoff (2.39 mm) than the WR&LR plots (not statistically significant), while the WH&LR plots had less runoff (1.08 mm) than the WR&LR plots (not significant). Sediment yield was lower in the WH&LR plots (0.50 t/km²) than in the WR&LR plots (0.52 t/km²) (not significant), but significantly higher in the WH&LE plots (2.10 t/km²) and LB&WR plots (1.57 t/km²) than in the WR&LR plots (p < 0.05). Conclusions: Managing invasive weeds independently reduces the risk of soil and water loss, but combined management with litter can exacerbate the issue. Invasive weed control and litter management should be performed separately in slope plantations. This study provides a scientific basis for soil and water conservation, restoration and rehabilitation of plantation ecosystems. Full article

Soybean is a high-value food source, and the invasive weeds Mexican prickly poppy (Argemone ochroleuca) could release allelochemicals that inhibit the growth of this crop. The impact of A. ochroleuca on the germination and growth of soybean is not well documented. Therefore, the aim of this study was to evaluate the TLC profiles of different extracts of A. ochroleuca and assess the effects of extracts on the germination of soybean seeds. Shoots and roots of A. ochroleuca were weighed and 100 g of each was separately extracted with 1000 mL deionized water, hexane or acetone. Ten concentrations of water extracts ranging from 10 to 100 mL per 100 mL of deionized water and three concentrations of acetone and hexane extracts ranging from 2.5 to 7.5 g/L were separately used for seed germination bioassays. Thin-layer chromatography (TLC) analysis was used to compare the chemical profiles in the shoot and root water, and in the hexane and acetone extracts of A. ochroleuca. The highest reduction was recorded from the water extract, at 100%. The TLC profiling of A. ochroleuca addressed different classes of compounds, including alkaloids, phenolic acids and flavanoids. There is, however, a need to identify the most active phytochemicals in the suppression of germination. Full article

The growth of Heteranthera reniformis, an invasive alien paddy weed, can be affected by cultivation practices. The experiments were conducted using herbicide-free soil to understand the effects of irrigation regimes and nutrient treatments on the growth of H. reniformis, as well as yield parameters while competing with a pre-existing seedbank. The pot experiments were conducted in a randomized complete block design (RBCD) with three replicates and twelve treatments. The four irrigation regimes (IRs): continuous irrigation (CI), soil condition at near saturation (non-puddled) (S), alternate wetting and drying (AWD) irrigation under two conditions [rewatered when the soil water potential reached −25 kPa (25P) and −35 kPa (35P)], and three nutrient treatments (NTs) of 0–0–0 NPK (NT₀), 40–25–30 NPK (NT₁), 80–50–60 NPK (NT₂), kg ha⁻¹ were established. The IRs had a significant effect on the growth of H. reniformis and other paddy field weeds, and the growth of H. reniformis was suppressed in the AWD regimes. NT₂ resulted in more rice panicles, higher grain yield, and increased irrigation water use efficiency (IWUE). The highest grain yield and protein content were observed in S–NT₂ and 25P–NT₂ treatments. The IR and NT can be maintained to prevent yield penalties and reduce the invasiveness of weeds. Full article

Environmental pollution, unintended harm to beneficial organisms, and the development of herbicide resistance among weeds are the main consequences of the massive and consistent use of chemical herbicides in recent decades. The growing need for alternative solutions has been reinforced by restrictive policies, leading to a search for natural herbicidal candidates. Mycoherbicides, formulations containing plant pathogenic fungi, are viewed as promising substitutes for chemical herbicides. In the case of Ailanthus altissima (Mill.) Swingle, one of the worst invasive alien tree species in the world, Verticillium-based mycoherbicides offer a viable method for control, inducing a lethal wilt disease and leading plants to death within a few years. The demonstrated significant effectiveness enables addressing challenges posed by other—conventional—approaches. The current analysis matches key internal (strengths and weaknesses) and external factors (opportunities and threats) of Verticillium Nees isolates as environmentally-friendly control agents against the invasive A. altissima, by listing each singularly and then crossing them among the categories, drawing from the collaborative efforts of American, Austrian, and Italian research teams. Full article

The intended or unintentional transport of soil material contaminated with weed seeds is one of the most important drivers in the spreading dynamics of invasive alien plants (IAPs). This phenomenon can be observed at any kind of construction site. Typical transfer of soil contaminated with IAP seeds can be observed along with road construction (soil translocation) or road maintenance services (deposit of mown plant biomass). Thus, an effective inactivation of these seeds by heating can avoid the spread of IAPs substantially. In the present study, the effects of various thermal control techniques (dry air heating and wet heating with hot steam, hot water, and hot foam) on seed survival of the widespread European IAPs common ragweed (Ambrosia artemisiifolia), narrow-leaved ragwort (Senecio inaequidens), and giant hogweed (Heracleum mantegazzianum) are discussed. Dry and wet seeds which were either uncovered or covered with soil were tested for survival at different treatment temperatures and different exposure times. Results revealed that particularly dry seeds of all three species could withstand temperatures of 100 °C for at least 6 h in climate chambers. Dry seeds of common ragweed and narrow-leaved ragwort survived exposure times of up to 48 h. Wet seeds were significantly more susceptible to heat treatments. Giant hogweed seeds were completely killed after 12 h at 70 °C. The exposure of IAP seeds to hot water was generally more effective than the treatment with hot steam. The treatment with hot foam was only effective when seeds were lying unprotected on the soil surface. Dry seeds of all the three species survived hot foam application in the field when they were covered by vegetation and leaf litter or soil. Due to the robustness of the seeds, a preventive management of IAPs by an efficient control before seeds formation is substantial to avoid their further dispersal. Full article

Accurate information concerning the spatial distribution of invasive alien species’ habitats is essential for invasive species prevention and management, and ecological sustainability. Currently, nationwide identification of suitable habitats for the highly destructive and potentially invasive weed, Solanum rostratum Dunal (S. rostratum), poses a series of challenges. Simultaneously, research on potential future invasion areas and likely directions of spread has not received adequate attention. This study, based on species occurrence data and multi-dimensional environmental variables constructed from multi-source remote sensing data, utilized Principal Component Analysis (PCA) in combination with the Maxent model to effectively model the current and future potential habitat distribution of S. rostratum in China, while quantitatively assessing the various factors influencing its distribution. Research findings indicate that the current suitable habitat area of S. rostratum covers 1.3952 million km², all of which is located in northern China. As the trend of climate warming persists, the potential habitat suitability range of S. rostratum is projected to shift southward and expand in the future; while still predominantly located in northern China, it will have varying degrees of expansion at different time frames. Notably, during the period from 2040 to 2061, under the SSP1-2.6 scenario, the habitat area exhibits the most significant increase, surpassing the current scenario by 19.23%. Furthermore, attribution analysis based on PCA inverse transformation reveals that a combination of soil, climate, spatial, humanistic, and topographic variables collectively influence the suitability of S. rostratum habitats, with soil factors, in particular, playing a dominant role and contributing up to 75.85%. This study identifies target areas for the management and control of S. rostratum, providing valuable insights into factor selection and variable screening methods in species distribution modeling (SDM). Full article

Ziziphus mauritiana Lam. (Rhamnaceae) (Chinee Apple, Indian Jujube, or Ber) is a significant woody weed in the drier tropics of northern Queensland, Western Australia, and the Northern Territory. Throughout these regions, its densely formed thickets influence the structure, function, and composition of rangeland ecosystems by outcompeting native pasture species. Despite this, the recent literature is heavily focused on the horticultural value of domesticated Ziziphus species in South Asia (China, India, and Pakistan), particularly its potential for poverty alleviation in arid or semi-arid areas. In fact, there has been comparatively little research undertaken on its invasiveness or associated ecological factors in pastoral contexts. Currently, the management of Z. mauritiana is limited to the application of synthetic herbicides or mechanical clearing operations. There is also considerable interest in the exploitation of host-specific, natural enemies (biological control agents, herbivorous insects, fungi, bacteria, or viruses) for limiting the vigour, competitiveness, or reproductive capacity of Z. mauritiana in northern Australia. The development of a “bioherbicide” in lieu of synthetic counterparts may foster a more resilient coexistence between agricultural systems and the natural environment owing to its reduced environmental persistence and increased target specificity. This review summarises the current literature on the weediness, ecological impacts, and current management of this problematic weed, thereby identifying (i) opportunities for further research and (ii) recommendations for improved management within its invasive range. Full article

Pueraria montana var. lobata is native to East Asia, and was introduced to many countries due to its potential for multiple uses. This species escaped under the management conditions soon after its introduction, and became a harmful weed species. This species has been listed in the top 100 of the world’s worst invasive alien species. P. montana stands expand quickly and threaten the native flora and fauna including microbiota. This species affects the concentration of carbon and nitrogen in soil and aquatic environments, and increases the amount of pollutants in the local atmosphere. Its infestation also causes serious economic losses on forestry and agriculture. Its characteristics of fast growth, thick canopy structure, enormous vegetative reproduction, and adaptative ability to the various environmental conditions may contribute to the invasiveness and naturalization of this species. The characteristics of P. montana regarding their defense functions against their natural enemies and pathogens, and allelopathy may also contribute to the invasiveness of this species. Potential allelochemicals such as xanthoxins, p-coumaric acid, caffeic acid, methyl caffeate and daidzein, and two isoflavones with anti-virus activity were identified in this species. In addition, fewer herbivore insects were found in the introduced ranges. These characteristics of P. montana may be involved in the invasive mechanisms of the species. This is the first review article focusing on the invasive mechanisms of this species. Full article

At present, many hypotheses have been proposed to explain the mechanism of alien plants’ successful invasion; the resource fluctuations hypothesis indicates that nutrient availability is a main abiotic factor driving the invasion of alien plants. Higher phosphorus utilization and absorption efficiency might be one of the important reasons for alien plants successful invasion. Wedelia trilobata, one of the notorious invasive weeds in China, possesses a strong ability to continue their development under infertile habitats. In this study, firstly, W. trilobata and its native congener, W. chinensis, were grown in various phosphorus forms to test their absorption efficiency of phosphorus. Secondly, the different responses of W. trilobata and W. chinensis to the insoluble phosphorus in three growth stages (at 30, 60, and 150 days cultivation) were also tested. The results showed that the growth rate, root morphology, and phosphorus absorption efficiency of W. trilobata under various insoluble, organic, or low phosphorus conditions were significantly higher than that of W. chinensis. During the short-term cultivation period (30 d), the growth of W. trilobata under insoluble and low phosphorus treatments had no significant difference, and the growth of W. trilobata in insoluble phosphorus treatment also had no significant effect in long-term cultivation (60 and 150 d). However, the growth of W. chinensis in each period under the conditions of insoluble and low phosphorus was significantly inhibited throughout these three growth stages. Therefore, invasive W. trilobata had a higher phosphorus utilization efficiency than its native congener. This study could explain how invasive W. trilobata performs under nutrient-poor habitats, while also providing favorable evidence for the resource fluctuations hypothesis. Full article