Major Invasive Species Research Articles

Mark-Release-Recapture Trial with Aedes albopictus (Diptera, Culicidae) Irradiated Males: Population Parameters and Climatic Factors.

Aedes albopictus is considered one of the major invasive species in the world and can transmit viruses such as dengue, Zika, or chikungunya. The Sterile Insect Technique (SIT) can be used to suppress the native populations of Ae. albopictus. Mark-release-recapture (MRR) studies are crucial to support the development of the release strategy during the SIT application. Meanwhile, weather conditions can affect the MRR trial's results and it is critical to understand the influence of climatic factors on the results. In October 2022, 84,000 irradiated sterile males were released for three consecutive weeks in Faro, Southern Portugal. Mosquitoes were recaptured by human landing collection (HLC) one, two, four, and six days after release. Generalized linear models with a negative binomial family and log function were used to estimate the factors associated with the number of recaptured mosquitoes, prevalence ratios, and the 95% confidence intervals (CIs). A total of 84,000 sterile male mosquitoes were released, with 528 recaptured (0.8%) by HLC. The prevalence of recaptured mosquitoes was 23% lower when the wind intensity was moderate. Marked sterile males had an average median distance travelled of 88.7 m. The median probability of daily survival and the average life expectancy were 61.6% and 2.1 days, respectively. The wild male population estimate was 443.33 males/ha. Despite no statistically significant association being found with humidity, temperature, and precipitation, it is important to consider weather conditions during MRR trial analyses to obtain the best determinant estimation and a more efficient application of the SIT in an integrated vector management program.

Current Status and Prospects of Pine Wilt Disease Management with Phytochemicals-A Review.

PWD (pine wilt disease) is a devastating forest disease caused by the Bursaphelenchus xylophilus, which is the major invasive species in Asian and European countries. To control this disease, fumigation, pesticide injection, and clear cutting of epidemic trees have been widely used. But these management strategies have many limitations in terms of the effectiveness and environmental impacts, especially for the overuse of chemical pesticides. Thus, PCs (phytochemicals), the various compounds extracted from plants, have drawn extensive attention owing to their special characteristics, including abundant sources, low toxicity, high efficacy, and easy degradation. This review provides an overview of the current status of using PCs as alternative approaches to manage PWD. It discusses the efficacy of various PCs, the factors influencing their nematicidal activity, and their mechanism of action against B. xylophilus. These results will reveal the application of PCs in combating these devastating diseases and the necessity for further research.

Future Range Expansions of Invasive Wasps Suggest Their Increasing Impacts on Global Apiculture.

Until now, no study has examined the future range dynamics of major invasive wasp species to assess their future impacts on global apiculture. Here, we developed 12 species distribution models to calibrate the future range dynamics of 12 major invasive Vespidae wasp species under a unified framework. An increase in their habitat suitability was identified in more than 75% of global land. Substantial range expansions were detected for all 12 species, and they were primarily induced by future climate changes. Notably, Polistes dominula and Vespa crabro had the largest potential ranges under all scenarios, suggesting their greater impact on global apiculture. Polistes chinensis and Vespa velutina nigrithorax had the highest range expansion ratios, so they warrant more urgent attention than the other species. Polistes versicolor and P. chinensis are expected to exhibit the largest centroid shifts, suggesting that substantial shifts in prioritizing regions against their invasions should be made. Europe and the eastern part of the USA were future invasion hotspots for all major invasive wasp species, suggesting that apiculture might face more pronounced threats in these regions than in others. In conclusion, given their substantial range shifts, invasive wasps will likely have increasingly negative impacts on global apiculture in the future.

Nesting ecology and confirmed breeding of the invasive pond slider Trachemys scripta in an urban environment, Romania

The pond slider (Trachemys scripta) is a major invasive species in freshwater habitats across the world. For decades, the main cause of individuals’ occurrences in the wild was the illegal release of pet animals. Recently, as an important component of their management, there has been an increasing focus on their ability to successfully reproduce in the invaded regions. In Romania, the species is reported as widespread in urban wetland environments within major cities, but information about its nesting and potential breeding remains scarce or anecdotal. We surveyed a large population of pond sliders in an artificial urban wetland site in Constanţa, SE Romania, and described their nesting ecology and reproductive output. Although eggs from several nests failed to hatch or were predated, potentially limiting their reproductive success, sliders were found to breed successfully at this site, with 18.6% viable hatchlings recorded. Our study could serve as a baseline for additional targeted surveys and to inform decision-making for successfully managing this invasive species. Although the importation, trading, and breeding of this species are prohibited by EU legislation, active and effective management is now required to address the successful reproduction and further potential spread of T. scripta.

The first high-quality genome assembly and annotation of Lantana camara, an important ornamental plant and a major invasive species

This study presents the first annotated, haplotype-resolved, chromosome-scale genome of Lantana camara, a flowering shrub native to Central America and known for its dual role as an ornamental plant and an invasive species. Despite its widespread cultivation and ecological impact, the lack of a high-quality genome has hindered the investigation of traits of both ornamental and invasive. This research bridges the gap in genomic resources for L. camara, which is crucial for both ornamental breeding programs and invasive species management. Whole-genome and transcriptome sequencing were utilized to elucidate the genetic complexity of a diploid L. camara breeding line UF-T48. The genome was assembled de novo using HiFi and Hi-C reads, resulting in two phased genome assemblies with high Benchmarking Universal Single-Copy Orthologs (BUSCO) scores of 97.7%, indicating their quality. All 22 chromosomes were assembled with pseudochromosomes averaging 117 Mb. The assemblies revealed 29 telomeres and an extensive presence of repetitive sequences, primarily long terminal repeat transposable elements. The genome annotation identified 83,775 protein-coding genes, with 83% functionally annotated. In particular, the study mapped 42 anthocyanin and carotenoid candidate gene clusters and 12 herbicide target genes to the assembly, identifying 38 genes spread across the genome that are integral to flower color development and 53 genes for herbicide targeting in L. camara. This comprehensive genomic study not only enhances the understanding of L. camara’s genetic makeup but also sets a precedent for genomic research in the Verbenaceae family, offering a foundation for future studies in plant genetics, conservation, and breeding.

An arrow in the quiver: evaluating the performance of Hyptis suaveolens (L.) Poit. in different light levels

BackgroundHyptis suaveolens (L.) Poit., native to the American tropics, is a pantropical annual plant and a major invasive species throughout India. It was anticipated that the availability of sunlight, coupled with its superior reproductive potential, persistent propagule bank, and dispersal ability, could lead to an increase in the growth and spread of this invader, thus potentially impeding herbaceous growth and diversity in non-native areas. Clarifying its ecological fitness and competitive performance will be useful to manage the spread of H. suaveolens in natural ecosystems that are facing a wide range of anthropogenic pressures.MethodsThe present study is a three-tier experiment. In the first tier, a field study was conducted to assess the patterns of H. suaveolens abundance and herbaceous species diversity in response to light availability (sun, 842–1072 µmol m–2 s−1 and shade 253–341 µmol m–2 s−1) in the tropical dry deciduous ecosystems in the Vindhyan highlands, India. Furthermore, the impact of H. suaveolens abundance on the resident native and non-native species abundance and diversity was also studied. In the second tier, a randomized common garden experiment was conducted to understand the trait fitness of H. suaveolens in sun (940 µmol m–2 s−1) and shade (300 µmol m–2 s−1) conditions. In the third tier, a plant growth chamber experiment with high-light (940 µmol m–2 s−1) and low-light (300 µmol m–2 s−1) treatments was done to learn how H. suaveolens partitions its biomass between aboveground and belowground plant parts.ResultsThe field study indicated that the sunlit areas had a higher abundance of H. suaveolens and a lower diversity of resident herbaceous species than the shaded areas. The common garden experiment showed that sun-dwelling H. suaveolens individuals performed better in germinative, vegetative, eco-physiological, and reproductive traits than the shade-dwelling individuals. The growth chamber experiment exhibited that plants grown in high-light environment had greater seed germination, seedling recruitment, and aboveground biomass than those grown in low-light environment, whereas plants grown in low-light environment exhibited a higher root mass ratio than the high-light individuals. These results suggest that H. suaveolens individuals mask the understory vegetation owing to higher seedling recruitment, relative growth rate, photosynthetic performance, resource acquisition-allocation, and reproductive output in response to high-light conditions.ConclusionsThe study concludes that light significantly controls the invasive population dynamics of H. suaveolens in dry deciduous forests. In high-light areas, H. suaveolens populations dominate the forest understory with suboptimal shade tolerance. In shade environment, H. suaveolens maintains a persistent soil seed bank along with ‘Oskar individuals’ that become active in response to high-light availability. The modus operandi is a ‘sit and wait’ strategy. The current study provides insights on prioritizing areas for H. suaveolens management that will potentially reduce the risk of biological invasions on the native species diversity of tropical regions.

A two-step species distribution modeling to disentangle the effect of habitat and bioclimatic covariates on Psacothea hilaris, a potentially invasive species

Integrating host plants in distribution modeling of phytophagous species and disentangling the effect of habitat and bioclimatic variables are key aspects to produce reliable predictions when the aim is to identify suitable areas outside species’ native range. To this aim, we implemented a framework of Species Distribution Model aimed at predicting potential suitable areas of establishment for the beetle Psacothea hilaris across the world. Since habitat (including host plants) and bioclimatic variables affect species distribution according to processes acting at different geographical scales, we modeled these variables separately. For the species native range, we fitted a habitat (HSM) and a bioclimatic (BSM) suitability model calibrated on a local and a large scale, respectively; the overall suitability map was obtained as the spatial product of HSM and BSM projection maps. ROC, TSS and Cohen’s Kappa obtained in validation confirmed a good predictive performance of modeling framework. Within HSM, host plants played a substantial effect on species presence probability, while among bioclimatic variables, precipitation of the warmer quarter and isothermality were the most important. Native HSM and BSM models were used to realize an overall suitability map at world scale. At global scale, many areas resulted suitable for habitat, some for bioclimate, and few for both conditions; indeed, if the species would not be able to modify its bioclimatic niche, it might not be considered a major invasive species. However, the high rate of range expansion documented for P. hilaris in Northern Italy, a poorly suitable bioclimatic area, suggests a plasticity of the species that requires increasing the level of attention to its invasive potential.

Fungal endophytes of the invasive grass Eragrostis lehmanniana shift metabolic expression in response to native and invasive grasses

Plant-fungal interactions shape ecosystem dynamics and are increasingly recognized as important in the success of invasive plants. Although diverse fungal endophytes are known to inhabit plants, including grasses, the precise chemical mechanisms through which they influence their hosts remain inadequately understood. We used untargeted metabolomics to characterize substrate use and compound production of three fungal endophytes isolated from an invasive grass, Eragrostis lehmanniana, characterizing the metabolome of these fungal isolates grown alone (axenically) and in the presence of seeds from invasive E. lehmanniana and co-occurring native grasses (E. intermedia, Bouteloua curtipendula, and Leptochloa dubia). We found that each fungal isolate expressed a different metabolic profile in response to Eragrostis seeds, relative to seeds of non-Eragrostis native grasses. Coupled with results of germination trials, these findings suggest that plant-fungal interactions mediated by the fungal metabolome may play a key role in determining the success of a major invasive species.

Skin lipids alone enable conspecific tracking in an invasive reptile, the Argentine black and white tegu lizard (Salvator merianae).

Locating potential mates in non-native habitats is one of the most important challenges faced by invasive vertebrate species. The Argentine black and white tegu lizard (Salvator merianae) is a major invasive reptile species in the contiguous United States and is rapidly expanding its range across Florida and the Southeast, in part due to inadequate management strategies and tools. Because a wide array of reptiles, especially squamates (snakes and lizards), have been well-studied for their reliance on chemical cues to locate conspecifics, our project aimed to isolate chemical cues from tegus and assess the ability of adult males and females to use only these cues to make navigation decisions within a Y-maze. Previously, we found that both males and females can follow conspecific scent trails, but the nature of the specific cues used by the tegus was unknown. In this study, we extracted skin lipids from male and female shed skins acquired during the breeding season then tested the extracts for bioactivity at different dilutions prior to Y-maze trials. Both sexes showed positive reactions (e.g., tongue-flicking, nose taps, scratching) to 2:1 skin lipid:hexane dilutions. In the Y-maze, males (n = 7) and females (n = 7) were run in three types of trailing scenarios with these skin lipid extracts: Male-only (pooled lipid extracts from male shed skins), Female-only (extracts from female shed skins), and Male vs. female. Regardless of the tegu lipid type present, tegus preferred to follow the conspecific lipid trail when paired with a neutral control (peanut oil; 2:1 dilution). They also preferred opposite-sex skin lipid trails when paired with same-sex skin lipid trails. We analyzed our results further by comparing them to those of Richard, Bukovich, et al. (2020). We found a synchronization effect of the skin lipids: sex differences in behavior detectable in the scent trail trials were absent when only conspecific skin lipids were present in the environment. Our results indicate that skin lipids alone are sufficient to facilitate mate tracking in S. merianae, these chemical cues induce reliable behavior, and extracted skin lipids have potential for modifying movement patterns of an invasive reptile in their non-native range. If leveraged in concert with current tegu management strategies (i.e., trapping), extracted skin lipids have the potential to bolster management efficacy but field trials are a requisite next step.

Biology, distribution, and management of invasive South American tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera; Gelechiidae), in Asia.

South American tomato leafminer, Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae), is native to South America, but is a major invasive and quarantine pest species in Europe, Africa, and Asia. It causes extensive damage of up to 100% yield loss in tomatoes (Solanum lycopersicum) in open and greenhouse conditions. Since its first invasion in Spain in 2006, it has spread rapidly into many countries in the Mediterranean and Western Europe and further invaded Africa and Asia. In Asia, it was first recorded in August 2009 in Turkey and spread to most South and East Asian countries. In this study, we reviewed existing work on the biology and distribution of T. absoluta in Asia, as well as the damage it causes. This review will help to develop efficient management tactics as well as establish quarantine and phytosanitary precautions in uninvaded countries.

Integrating UAV data to explore the relationship between microtopographic variation and Spartina alterniflora expansion during its early invasion

As a major invasive species in coastal China, Spartina alterniflora (S. alterniflora) has seriously threatened the ecological functions of coastal wetlands. Based on multisource high-precision geospatial data obtained by unmanned aerial vehicles (UAVs), the shape and distribution of S. alterniflora patches were extracted and analysed by using object-oriented classification and the landscape pattern index in this study. Considering microtopographic variations, the trend-surface subregions were delimited. In this way, we examined the relationship between S. alterniflora distribution and expansion and the variation in microtopography and tidal hydrology in the early invasion stage. The results showed that the microtopography silted up acceleration from land to sea, and the inundation time was reduced significantly in the study area for 2020–2022. In 2020, the average area of S. alterniflora patches showed a decreasing trend from land to sea. The distribution of patches on both sides of the sea and land was relatively concentrated and dispersed in the middle. By 2022, S. alterniflora presented a rapid expansion, with the total area expanding from 8488.57 m2 to 18470.72 m2. With the variation in microtopography, the characteristics of S. alterniflora patch expansion presented regional differences: Due to the small microtopographic and tidal hydrological variations, the patches fluctuated outwards slightly (average variation distance was 0.93 m) near the dike. The patches in the seaside front area had an annular expansion, and the expansion speed positively correlated with the area of the original patch. In the central region, the small patches merged and filled to form an S. alterniflora belt, while a large number of new small patches appeared. In general, the heterogeneous environment formed by microtopographic variations was conducive to the colonization and growth of S. alterniflora, but the excessive slope could inhibit expansion. This study will provide a theoretical basis for coastal ecological management and rapid control of S. alterniflora expansion.

Intelligent Identification of Pine Wilt Disease Infected Individual Trees Using UAV-Based Hyperspectral Imagery

The pine wood nematode (PWN; Bursaphelenchus xylophilus) is a major invasive species in China, causing huge economic and ecological damage to the country due to the absence of natural enemies and the extremely rapid rate of infection and spread. Accurate monitoring of pine wilt disease (PWD) is a prerequisite for timely and effective disaster prevention and control. UAVs can carry hyperspectral sensors for near-ground remote sensing observations, which can obtain rich spatial and spectral information and have the potential for infected tree identification. Deep learning techniques can use rich multidimensional data to mine deep features in order to achieve tasks such as classification and target identification. Therefore, we propose an improved Mask R-CNN instance segmentation method and an integrated approach combining a prototypical network classification model with an individual tree segmentation algorithm to verify the possibility of deep learning models and UAV hyperspectral imagery for identifying infected individual trees at different stages of PWD. The results showed that both methods achieved good performance for PWD identification: the overall accuracy of the improved Mask R-CNN with the screened bands as input data was 71%, and the integrated method combining prototypical network classification model with individual tree segmentation obtained an overall accuracy of 83.51% based on the screened bands data, in which the early infected pine trees were identified with an accuracy of 74.89%. This study indicates that the improved Mask R-CNN and integrated prototypical network method are effective and practical for PWD-infected individual trees identification using UAV hyperspectral data, and the proposed integrated prototypical network enables early identification of PWD, providing a new technical guidance for early monitoring and control of PWD.

The diet of commensal Crocidura olivieri (Soricomorpha: Soricidae): predation on co-existing invasive Mus musculus suggested by DNA metabarcoding data

Abstract Crocidura olivieri is a large-sized shrew species showing a clear trend towards commensalism in West Africa, where it co-occurs and interacts with a number of rodent species in indoor small mammal communities. Among the rodents present is the house mouse Mus musculus, a major invasive species worldwide. We here test the hypothesis that M. musculus could be part of the diet of C. olivieri in a number of localities of Senegal where the two species are known to coexist. We use a metabarcoding approach based on the high-throughput sequencing of a 133 bp fragment of the COI gene, on DNA extracted from digestive tracts and faeces of a sample of 108 shrews. Beside insects of various groups (ants, beetles and cockroaches especially) representing usual items of shrew’s diet, and traces of domestic mammals and poultry that were probably scavenged, several species of rodents were evidenced. Among them, M. musculus was by far the best represented species, found in 17 of the 54 shrews where at least one prey taxon was identified. This finding tends to confirm the potential role of C. olivieri as predator of house mice, while highlighting the capacity of this species to adapt its diet to environmental conditions.

Pest categorisation of Solenopsis invicta.

The EFSA Panel on Plant Health performed a pest categorisation of Solenopsis invicta Butler (Hymenoptera: Formicidae) the red imported fire ant, for the EU territory. S. invicta is native to central South America and has spread to North and Central America, East Asia and Australia where it is recognised as a major invasive species causing serious environmental impacts to biodiversity and harming horticultural crops such as cabbage, eggplant and potatoes. It can girdle and kill young citrus trees. S. invicta is not listed as a Union quarantine pest in Annex II of Commission Implementing Regulation (EU) 2019/2072. However, the European Scientific Forum on Invasive Alien Species lists S.invicta as a species of Union concern (Commission Implementing Regulation (EU) 2022/1203). Like other ant species, S. invicta is a social insect commonly creating colonies in the soil. Long-distance spread in the Americas has been attributed to nests being carried in soil accompanying plants for planting, or simply in soil alone. S. invicta could enter the EU via conveyances carrying a wide range of goods if the conveyance is contaminated with soil or has been in close contact with soil, and with plants for planting in soil or growing media. Climatic conditions in large parts of the southern EU are suitable for establishment and spread would occur when mated females disperse to form new colonies. If S. invicta established in the EU, losses to horticultural crops would be expected in addition to losses to biodiversity. The impacts of S. invicta go beyond plant health with the ant attacking new-born, hatching, weak or sick animals. Stings can cause allergic reactions in humans and are a public health issue. However, such factors are outside the scope of a pest categorisation. S. invicta satisfies the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest.

Interspecific competition predicts the potential impact of little fire ant Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae) invasion on resident ants in southern China.

The little fire ant Wasmannia auropunctata (Roger) is a major invasive species that seriously threatens the biodiversity of invaded areas. W. auropunctata was first reported in Chinese mainland in 2022 and its impact on native species is still unknown. To evaluate the impact of W. auropunctata invasion on the ant communities in southern China, a series of interspecific competition experiments were conducted in this study. The individual aggression index and group aggression experiments showed the advantage of W. auropunctata in competition with 5 resident ants under equal worker numbers. When encountering Anoplolepis gracilipes, Camponotus nicobarensis, Tetramorium bicarinatum, Polyrhachis dives, and Solenopsis invicta, W. auropunctata gradually gained a competitive advantage with an increase in its number of workers. In the group aggression experiments with equal worker numbers, there was a negative correlation between the body length and mortality rate of resident ants. The results of the foraging behavior experiments showed that W. auropunctata was able to dominate food resources under competition with Carebara diversa, which also displayed weak competition in the group aggression bioassay. In addition, the abilities to recruit workers and retrieve food were inhibited under competition with S. invicta and T. bicarinatum. The results of the nesting behavior experiments showed that in the 24-h bout of space resource competition, W. auropunctata was dominant over C. diversa, S. invicta, and T. bicarinatum. The results of this study show that W. auropunctata has certain advantages in competition for food and space resources over resident ants in southern China, and some resident ant species may be replaced in the future.

Remote Sensing Monitoring of Pine Wilt Disease Based on Time-Series Remote Sensing Index

Under the strong influence of climate change and human activities, the frequency and intensity of disturbance events in the forest ecosystem both show significant increasing trends. Pine wood nematode (Bursapherenchus xylophilus, PWN) is one of the major alien invasive species in China, which has rapidly infected the forest and spread. In recent years, its tendency has been to spread from south to north, causing serious losses to Pinus and non-Pinus coniferous forests. It is urgent to carry out remote sensing monitoring and prediction of pine wilt disease (PWD). Taking Anhui Province as the study area, we applied ground survey, satellite-borne optical remote sensing imagery and environmental factor statistics, relying on the Google Earth Engine (GEE) platform to build a new vegetation index NDFI based on time-series Landsat images to extract coniferous forest information and used a random forest classification algorithm to build a monitoring model of the PWD infection stage. The results show that the proposed NDFI differentiation threshold classification method can accurately extract the coniferous forest range, with the overall accuracy of 87.75%. The overall accuracy of the PWD monitoring model based on random forest classification reaches 81.67%, and the kappa coefficient is 0.622. High temperature and low humidity are conducive to the survival of PWN, which aggravates the occurrence of PWD. Under the background of global warming, the degree of PWD in Anhui Province has gradually increased, and has transferred from the southwest and south to the middle and northeast. Our results show that PWD monitoring and prediction at a regional scale can be realized by using long time-series multi-source remote sensing data, NDFI index can accurately extract coniferous forest information and grasp disease information in a timely manner, which is crucial for effective monitoring and control of PWD.

Structure and Composition of Vegetation and Status of Invasion in Different Forest Types of Western Himalaya

Present study deals with qualitative and quantitative assessment of vegetation in four most dominated forest types of western Himalaya, Sal (Shorea robusta) forest, Chir-Pine (Pinus roxburghii) forest, Banj-oak (Quercus leucotrichophora), and Deodar forest (Cedrus deodara) between 600 to 2100 m asl elevation. These forests serve the lifeline for local communities for their daily sustenance. A total of 336 species belonging to 277 genera and 98 families were recoded from study area. Total basal cover (TBC) ranged between 24.05 to 35.15 m² ha^-1, Tree density ranged from 472 to 1068, shrub’s density varied between 1930 to 4080 whereas herbs ranged from 53600 to 80008 individual per hectare. Maximum tree density was recorded (1068 ind. ha^-1) at the oak stand and minimum (472 ind. ha^-1) recorded at the Sal forest. Species richness, Shannon-Wiener diversity index and TBC increase from Sal to oak forest. It was observed that temperate oak forests in study area comprised higher diversity and species richness at tree, shrub and herb layer, Sal forest depicted higher regeneration. Major invasive species in study area were Lantana camara, Ageratina adenophora, Ageratum conyzoides and Parthenium hysterophorous. In present study, Ageratina adenophora recorded an elevation of about 2100m asl, which is the alarming sign for local biodiversity and may cause a serious threat to Himalayan biodiversity.

Proliferation of Invasive Alien Species in Different Forest Types of Western Himalaya

Present study was carried out to understand the proliferation status of invasive alien species (IAS) along altitudinal gradient (650-2150 m) in different forest types (Sal, Pine, Oak and Deodar) of western Himalaya. To understand the trend of proliferation of invasive species repeat vegetation survey and quantitative analysis method used in same plots after two years. Major invasive species in the region were Lantana camara, Ageratina adenophora, Ageratum conyzoides and Parthenium hysterophorus. Ageratina adenophora was highly spreading invasive species present in all forest type of the study area. Maximum density (8394 ind/ha.) and frequency (64.15%) was recorded in Pine forest. Important value index (IVI) of Ageratina adenophora increase from 23.4 to 25.71 in Pine forest followed by in Sal forest (6.32 to 8.21) and Deodar forest (11 to 12.53). Maximum density (246 ind/ha.) and frequency (41%) of Lantana camara recorded in Sal forest and IVI increase from 29.9 to 30.78. Oak forest allowed less rate of invasion of alien species. In study area with increase elevation number of invasive species decrease. However, high proliferation rate of Ageratina adenophora recorded at an elevation 2150 m asl in moist Deodar forest.

Invasive Alien Plant Species for Use in Paper and Packaging Materials

Invasive plant species can impede the establishment and growth of native plants and affect several ecosystem properties. These properties include soil cover, nutrient cycling, fire regimes, and hydrology. Controlling invasive plants is therefore a necessary, but usually expensive, step in restoring an ecosystem. The sustainability of materials with an emphasis on the use of local resources plays an important role in the circular economy. The use of alternative fibers from invasive plants promotes local production in smaller paper mills that offer the protection of local species and the reduction of waste and invasive plants. A synthesis of the literature is needed to understand the various impacts of invasive plants and their practical control in the context of papermaking applications and to identify associated knowledge gaps. To improve our understanding of the practical application of invasive species in the paper industry, we reviewed the existing literature on invasive plant species in the area of fiber production, printability, coating solution production, dyes, and extracts, and collected information on the major invasive plant species in Europe and the methods used for various applications.

Testing for Hybridization between Centaurea stoebe and Centaurea jacea (Asteraceae) in the Isolated Island Setting of Nantucket, Massachusetts, U.S.A.

Spotted knapweed (Centaurea stoebe) and brown knapweed (Centaurea jacea) are members of the Asteraceae and natives of Eurasia. Centaurea stoebe is a major invasive species in North America, dominating large stretches of grassland. It also is known to form hybrids in North America with closely related naturalized Centaurea spp., including C. jacea. Both species were introduced on Nantucket Island, a coastal island 44 km south of Cape Cod, Massachusetts, and morphologically unusual, possible hybrid populations have been reported. The aim of this study was to test for hybridization between these weeds in an isolated setting. Chloroplast marker sequences revealed that all the hybrid-like plants shared the same haplotype with C. jacea populations. The analysis of nuclear markers with microsatellite markers showed surprisingly little intra- and inter-specific gene flow between populations and no evidence of hybridization between C. stoebe and C. jacea. Two populations with hybrid-like morphology are most likely environmental plastic morphs of C. jacea.