Early Stages Of Invasion Research Articles

Effects of Different Degrees of Xanthium spinosum Invasion on the Invasibility of Plant Communities in the Yili Grassland of Northwest China.

Studying the effects of different degrees of exotic plant invasion on native plants' community structure and plant diversity is essential for evaluating the harm caused to ecosystems by plant invasion. In this study, we investigated the effects of Xanthium spinosum, a widespread invasive species, on plant community species diversity and community stability in the Ili River Valley area of Xinjiang, China, under three invasion levels (no invasion and low, moderate, and heavy invasion), and the competitive advantage index, invasion intensity, and contribution of plant community species diversity to community stability and invasibility were determined for the prickly fungus under different degrees of invasion. The results show that there were significant differences (p < 0.05) in the species diversity and community stability of plant communities caused by different degrees of invasion of X. spinosum. The species diversity and stability of plant communities were negatively correlated with the community invasibility, competitive advantage, and invasion intensity of X. spinosum (p < 0.05); therefore, the competitive advantage and invasion intensity of X. spinosum increase with the increase of its invasion degree. On the contrary, community species diversity and stability decreased with the increase of its invasion degree, ultimately leading to differences in community invasibility under different invasion degrees. The Shannon-Wiener and Simpson's indices were the greatest contributors to community stability and invasibility, respectively. Moderate and heavy levels of invasion by X. spinosum reduced the diversity and stability of local plant communities, increased the invasibility of communities, and substantially affected the structures of plant communities. Therefore, the continued invasion by X. spinosum will have an immeasurable impact on the fragile ecosystems and diversity of indigenous species in Xinjiang. We recommend that this invasive species be controlled and eradicated at the early stages of invasion to prevent further harm.

Distribution of the Cannabis sativa L. in the Western Himalayas: A tale of the ecological factors behind its continuous invasiveness

The invasion of species in new regions depends on multiple factors, especially, the prevailing environmental factors. The environmental conditions are essential to understand for planning effective management strategies related to invasive species. Little is known about Cannabis as an established invasive weed. We hypothesized that the successful establishment of this invading species is influenced by the environmental variables; however, some of them have a much stronger influence than the others. Quantitative ecological methods were adopted for sampling the habitats invaded by Cannabis sativa, in a total of 165 quadrats. Soil samples were collected for soil analyses from each of those quadrat. Ecological and statistical approaches including Structure Equation Modeling (SEM) procedures were applied to evaluate the impact of environmental factors, ecological interrelationships, and the resultant invasiveness of the C. sativa. Our findings indicate that elevation, temperature, humidity, anthropogenic pressure, physio-chemical prperties of soil and habitat degradation play significant roles in determining the distribution and abundance of C. sativa. Principal Component Analysis (PCA) of the parameters further clarifies that elevation is the most important driver in explaining the successful establishment of the invader species with a 30.1% variance. Structural equation modeling further confirms the significant role played by elevation, which not only directly affects the abundance of Cannabis but also indirectly influences other variables such as anthropogenic pressure, temperature, and humidity etc. However, the invasion of C. sativa is less affected by soil saturation pH, electrical conductivity, phosphorous, potassium, and CaCO3. Our study provides valuable scientific information that could be used for the early detection of invasive species at the early stage of invasion and in devising policies for their management and control.

Insights from the past: Invasion trajectory and niche trends of a global freshwater invader.

Freshwater ecosystems are invaded by a non-random selection of taxa, among which crayfish stand out with successful examples worldwide. Species distribution models (SDMs) have been used to detect suitable areas for invasive species and predict their potential distributions. However, these prediction exercises assume the stability of realized environmental niches, which is uncertain during invasion. Worldwide evaluations involving cosmopolitan invaders may be particularly useful but have seldom been considered. Focusing on the successful invasion history of the red swamp crayfish, Procambarus clarkii, we assessed its geographic expansion and niche trends over time. Based on global occurrences from 1854 to 2022, multiple sequential SDMs have been implemented based on a set of bioclimatic variables. The environmental suitability for each period was projected through to the next period(s) using an ensemble procedure of commonly used SDM algorithms. As the records of the species are known, it was possible to check whether the modelling projections were concordant with the observed expansion of red swamp crayfish at a global scale. This also permitted analysis of its realized niche, and its dynamics, during different expansion phases. SDM maps based on past species records showed concordance with the known crayfish distributions and yielded similar spatial patterns with outputs overperforming random combinations of cells in term of suitability. The results also reflect the stability of the species niche, which despite some expansions during the invasion process, changed little in terms of main position in functional space over time. SDMs developed in the early stages of invasion provide useful insights but also tend to underpredict the potential range compared to models that were built for later stages. Our approach can be easily transferable to other well-documented taxa and represents valuable evidence for validating the use of SDMs, considering a highly dynamic world where biogeographical barriers are often bypassed.

Early stage of invasion of the quagga mussel (Dreissena rostriformis bugensis) within the interconnected lakes Lough Ree and Lough Derg of the Shannon River system, Ireland

Quagga and zebra mussels of the genus Dreissena are two of the most impactful freshwater invasive alien species that have spread widely across the globe. These species attach to natural and artificial substrates, form dense populations and filter large volumes of water causing ecological and economic damage. Following the quagga mussel’s discovery in the Shannon River system in Ireland, this study assesses its local distribution, population density, relative abundance, and population structure in the interconnected lakes Lough Ree and Lough Derg in order to determine the likely year and location of its introduction. Polymodal length-frequency analysis was used to distinguish between year cohorts and estimate growth rates. The quagga mussel is established widely across both lakes and is settling on a range of artificial surfaces, natural substrates, dead shells, plant material, and other invasive bivalves. High densities of quagga mussels exceeding 20 000 individuals per m2 were present on artificial surfaces in Lough Ree with total dreissenid densities reaching 26 758 per m2. The relative abundance of quagga mussels to zebra mussels on natural substrates is high in Lough Ree (up to 94.7%) and low in Lough Derg (up to 16.8%). Two to four year cohorts were present at all sites, with quagga mussels attaining large shell sizes over 34 mm in length. Growth varied between sites with a maximum estimated yearly growth rate of 16.8 mm. The time and place of the quagga mussel’s initial introduction in Ireland is still uncertain, but its widespread distribution, population structure, and high population density and relative abundance suggest it was first introduced to Lough Ree in 2016 or 2017.

Patterns of Prunus cerasifera early invasion stages into a temperate primeval forest

AbstractThe cherry plum (Prunus cerasifera Ehrh.) is considered an invasive plant species in numerous areas of the temperate climate zones around the world. Although this exotic tree can naturalize in a wide spectrum of forest ecosystems, its invasion mechanisms remain totally unknown. This study is the first approach aiming to investigate potential drivers shaping the ecological success of P. cerasifera invasion, with an example of the temperate primeval forest as a model recipient ecosystem. Using generalized linear models, we suggest that the distance to the propagule source may shape considerably this exotic species occurrence in primeval forest’s understory, expressed by the presumably high role of birds and small mammals in short-, and large ungulates in long-distance seed dispersion. The probability of this invader occurrence decreased with decreasing functional and phylogenetic diversity of understory vegetation. This suggests the importance of habitat filtering generated in small tree-fall gaps in shaping the P. cerasifera success. Thus, interactions between natural disturbances, characteristics of recipient vegetation, as well as traits of various animal dispersers, may be identified as key drivers promoting the occurrence of P. cerasifera in the primeval forest ecosystem. However, further studies on the patterns of P. cerasifera invasion are needed to identify drivers promoting invasion, as well as the effects of this exotic plant on biodiversity and the functioning of ecosystems.

The elicitor VP2 from Verticillium dahliae triggers defence response in cotton.

Verticillium dahliae is a widespread and destructive soilborne vascular pathogenic fungus that causes serious diseases in dicot plants. Here, comparative transcriptome analysis showed that the number of genes upregulated in defoliating pathotype V991 was significantly higher than in the non-defoliating pathotype 1cd3-2 during the early response of cotton. Combined with analysis of the secretome during the V991-cotton interaction, an elicitor VP2 was identified, which was highly upregulated at the early stage of V991 invasion, but was barely expressed during the 1cd3-2-cotton interaction. Full-length VP2 could induce cell death in several plant species, and which was dependent on NbBAK1 but not on NbSOBIR1 in N. benthamiana. Knock-out of VP2 attenuated the pathogenicity of V991. Furthermore, overexpression of VP2 in cotton enhanced resistance to V. dahliae without causing abnormal plant growth and development. Several genes involved in JA, SA and lignin synthesis were significantly upregulated in VP2-overexpressing cotton. The contents of JA, SA, and lignin were also significantly higher than in the wild-type control. In summary, the identified elicitor VP2, recognized by the receptor in the plant membrane, triggers the cotton immune response and enhances disease resistance.

Physics of collective cell migration.

Movement of cell clusters along extracellular matrices (ECM) during tissue development, wound healing, and early stage of cancer invasion involve various inter-connected migration modes such as: (1) cell movement within clusters, (2) cluster extension (wetting) and compression (de-wetting), and (3) directional cluster movement. It has become increasingly evident that dilational and volumetric viscoelasticity of cell clusters and their surrounding substrate significantly influence these migration modes through physical parameters such as: tissue and matrix surface tensions, interfacial tension between cells and substrate, gradients of surface and interfacial tensions, as well as, the accumulation of cell and matrix residual stresses. Inhomogeneous distribution of tissue surface tension along the cell-matrix biointerface can appear as a consequence of different contractility of various cluster regions. While the directional cell migration caused by the matrix stiffness gradient (i.e., durotaxis) has been widely elaborated, the structural changes of matrix surface caused by cell tractions which lead to the generation of the matrix surface tension gradient has not been considered yet. The main goal of this theoretical consideration is to clarify the roles of various physical parameters in collective cell migration based on the formulation of a biophysical model. This complex phenomenon is discussed with the help of model systems such as the movement of cell clusters on a collagen I gel matrix, simultaneously reviewing various experimental data with and without cells.

Identifying links between the biodiversity impacts and monetary costs of alien birds

Abstract Alien species can be damaging to native biodiversity, human well‐being and the economy. Identifying the complete range of impacts they cause, and the ways that these impacts are connected, may inform the prioritisation of management actions to mitigate impacts. Using datasets on the biodiversity impacts and monetary costs (damage and management costs) of alien birds, we aimed to establish whether species with the most severe biodiversity impacts also had the highest costs; whether types of biodiversity impact were associated with high costs; and whether specific factors associated with alien species are linked to both damaging biodiversity impacts and high costs. We identified a positive relationship between a specific type of biodiversity impact (predation) and costs, possibly because predation by alien birds can be severely damaging to native species and therefore attracts management actions. However, predation impacts are likely to occur more frequently and to be easier to identify than some other impact mechanisms such as hybridisation and transmission of diseases, and they are therefore likely to be more frequently managed and hence to have costs. We identified a specific species characteristic (generalism) to be associated with severe biodiversity impacts and high costs, probably because generalist species have greater opportunity to cause impacts, whether they be on biodiversity or the economy, or both. We also found widely distributed alien birds to be associated with high costs, probably because these species also have greater opportunity to cause impacts. Management interventions that prevent the introduction of both predatory and generalist alien bird species, or that reduce their geographic distribution at early stages of invasions, may have significant biodiversity and economic benefits. Read the free Plain Language Summary for this article on the Journal blog.

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.

Research on Detection of Ultra-Low Concentration Anthrax Protective Antigen Using Graphene Field-Effect Transistor Biosensor.

Protective antigen (PA) is an important biomarker for the early diagnosis of anthrax, and the accurate detection of protective antigen under extremely low concentration conditions has always been a hot topic in the biomedical field. To complete the diagnosis of anthrax in a timely manner, it is necessary to detect PA at extremely low concentrations, as the amount of PA produced in the early stage of anthrax invasion is relatively small. Graphene field-effect transistor (Gr-FET) biosensors are a new type of material for preparing biosensors, with the advantages of a short detection time and ultra-low detection limit. The effect of different concentrations of diluents on the affinity of PA monoclonal antibodies was determined via an ELISA experiment. Combined with the Debye equation, 0.01 × PBS solution was finally selected as the diluent for the experiment. Then, a PA monoclonal antibody was selected as the bio-recognition element to construct a Gr-FET device based on CVD-grown graphene, which was used to detect the concentration of PA while recording the response time, linear range, detection limit, and other parameters. The experimental results showed that the biosensor could quickly detect PA, with a linear range of 10 fg/mL to 100 pg/mL and a detection limit of 10 fg/mL. In addition, the biosensor showed excellent specificity and repeatability. By constructing a Gr-FET device based on CVD-grown graphene and selecting a PA monoclonal antibody as the bio-recognition element, a highly sensitive, specific, and repeatable Gr-FET biosensor was successfully prepared for detecting extremely low concentrations of anthrax protective antigen (PA). This biosensor is expected to have a wide range of applications in clinical medicine and biological safety monitoring.

Correlation of Pap Smear and Colposcopy in Relation to Histopathological Findings in Detection of Preinvasive Lesion of Cervix in Bangabandhu Sheikh Mujib Medical University Hospital Dhaka Bangladesh

Background: Cervical cancer develops from well-defined precursor lesions in a variable period of time. Detecting in early or pre invasive stages, cervical cancer is preventable and curable, so detection of preinvasive lesions is very important. Objectives: The aim of our study was to correlate of Pap smear and colposcopy in relation to histopathological findings in detection of preinvasive lesion of cervix. Methods: This was a cross-sectional study of 110 women to attend in department of Gynecological Oncology OPD of Bangabandhu Sheikh Mujib Medical University Hospital from July 2016 to June 2017. Inclusion criteria were age of 30 to 60 years, who had unhealthy cervix, intermenstrual or post coital bleeding and excessive vaginal discharge. Exclusion criteria were any cervical growth, bleeding at the time of examination, pregnant women. Result: In present study sensitivity of Pap smear for detecting lesions above LSIL was 11(10.0%), specificity 68.38%, PPV was 94.44%, negative predictive value 71.86%. The incidence of preinvasive lesions (LSIL and HSIL) was 33.64% with LSIL 21(19.09%) and HSIL 16(14.55%) and of carcinoma were 10(9.09%). Conclusion: With a comprehensive approach to make awareness and doing proper screening by Paps smear, colposcopy and colposcopy directed biopsy; cervical cancer can be eliminated as a public health problem within a generation. Bangladesh Medical Res Counc Bull 2022; 48(3): 189-194

Enhancing tomato resistance by exploring early defense events against Fusarium wilt disease

Studying plant early immunity, such as the unique immune mechanisms against pathogens, is an important field of research. Tomato wilt resulting from the infection by Fusarium oxysporum f. sp. lycopersici (Fol) is an important soil-borne vascular disease. In this study, we challenged tomato plants with Fol for a time-course RNA sequencing (RNA-seq) analysis. The result indicated that phenylpropanoid and flavonoid pathway genes were significantly enriched during the early invasion stage. Further study revealed that the flavonoids galangin and quercetin could effectively inhibit Fol growth and enhance wilt resistance in tomato. Moreover, the genes involved in plant-pathogen interactions, the MAPK signaling pathway, and plant hormone signal transduction were significantly enriched. These genes were also involved in plant pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) signaling pathways. Strikingly, the transcription levels of pathogen-related protein 1 (SlPR1) were dramatically increased at 2 days post Fol inoculation, implying that SlPR1 is important in early immunity in tomato. SlPR1 does not have direct antifungal activity. Instead, its C-terminal peptide CAPE1 could activate root defense responses, such as the reactive oxygen species (ROS) burst, salicylic acid (SA)/jasmonic acid (JA) production, and defense-related gene expression, which collectively increased tomato resistance to Fol infection. In addition, CAPE1 could induce systemic acquired resistance (SAR). Application of CAPE1 onto tomato leaves induced local resistance to the pathogen Botrytis cinerea and systemic resistance to Fol infection. These results advanced our understanding for the early immunity against Fol in tomato and provide potential strategy for tomato disease control.

Out of East Asia: Early Warning of the Possible Invasion of the Important Bean Pest Stalk-Eyed Seed Bug Chauliops fallax (Heteroptera: Malcidae: Chauliopinae)

The short stay at the beginning of the invasion process is a critical time for invasive species identification and preventing invasive species from developing a wider distribution and significant economic impact. The stalk-eyed seed bug Chauliops fallax is an important agricultural pest of soybean and was first reported to occur outside East Asia. Here, we reported the native evolutionary history, recent invasion history, and potential invasion threats of C. fallax for the first time based on population genetic methods and ecological niche modelling. The results showed that four native East Asian genetic groups (EA, WE, TL, and XZ) were well supported, showing an east-west differentiation pattern consistent with the geographical characteristics of three-step landforms in China. Two main haplotypes existed: Hap1 might have experienced a rapid northwards expansion process after the LGM period, and Hap5 reflected local adaptation to the environment in southeastern China. The Kashmir sample was found to come from the recent invasion of populations in the coastal areas of southern China. Ecological niche modelling results suggested that North America has a high risk of invasion, which might pose a serious threat to local soybean production. In addition, with future global warming, the suitable habitat in Asia will move towards the higher latitude region and gradually deviate from the soybean planting area, which indicates the threat of C. fallax to soybean production in Asia will decrease in the future. The results could provide new insights into the monitoring and management of this agricultural pest in the early invasion stage.

Abstract 5817: LKB1 overcomes RAS pathway-mediated loss of epithelial integrity

Abstract Oncogenic RAS pathway disassembles cell-cell and cell-basement membrane junctions, thus promoting epithelial cell motility and invasion. To find tumor proteomic changes responsible for the disrupting effects of RAS on epithelial integrity, we explored cBioportal cell line proteomics data across all cancer types for correlations between oncogenic KRAS or HRAS mutations and possible regulators of epithelial integrity. We found inverse correlation between these RAS mutations and tumor suppressor LKB1 protein levels in a cohort where LKB1 was not inactivated by a mutation. Furthermore, LKB1 protein levels were also positively correlated with NF2 protein (a negative regulator of RAS) in human breast tumors and inversely correlated with c-RAF (RAS effector) activating phosphorylation at serine 338 in breast cancer cell lines. We sought to functionally clarify the relationship between RAS pathway and LKB1, finding that an ectopic constitutive or inducible expression of HRASV12 downregulates LKB1 protein in mammary epithelial MCF10A cells and HMEC-hTERT cells. Furthermore, RAS-mutant MCF10A cells regained LKB1 protein levels upon treatment with MEK/ERK inhibitors. We establish that the RAS-mediated downregulation of LKB1 protein occurs through proteasomal activity. LKB1 reconstituted MCF10A-HRASV12 (RAS-LKB1) cells displayed restored desmoplakin, γ-catenin and E-cadherin pericellular immunostaining pattern in monolayer cultures, suggesting restoration of desmosomes and adherence junctions. We also cultured RAS-LKB1 cells in 3D egg-white and observe restoration of E-cadherin, γ-catenin, α6-integrin, and laminin-332, indicating a rescue of epithelial integrity in 3D context. Our findings suggest that LKB1 rescues mutant RAS-mediated disruption of cell-cell and cell-basement membrane junctions and general epithelial integrity. Our current aim is to define how LKB1 suppresses RAS mediated disruption of breast epithelial integrity, that is expected to shed new light into early stages of tumor invasion and uncover novel therapeutic opportunities via restoration of LKB1. Citation Format: Topi A. Tervonen, Shishir M. Pant, Johanna Englund, Juha Klefström. LKB1 overcomes RAS pathway-mediated loss of epithelial integrity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5817.

The Influence of Invasive Alien Plants on Umbrella Butterflies of the GenusPhengarisand Diversity of Heteroptera True Bugs

AbstractThe Natura 2000 initiative and National Parks are the most important forms of nature protection in European countries. However, conservation efforts are often hampered by biological invasions, which are some of the most serious environmental problems. The aim of this study was to assess, in protected areas, the impacts of invasive plants – alienSolidagospp. onPhengarisbutterflies andHeracleum mantegazzianumon Heteroptera true bugs.Ph. teleiusandPh. nausithouswere surveyed in the Jaworzno Meadows Natura 2000 site using the Capture-Mark-Recapture method. Heteroptera were surveyed using transect captures in Magurski National Park. The sizes of local populations of the butterflies were lower in patches with higher goldenrod cover. A high cover of the host plant may mitigate the negative impact of goldenrod during the early stage of invasion. In the case of poor habitat quality, nearby unprotected habitat patches act as ecological traps for butterflies due to the application of mowing during the butterfly flight period. The invasive giant hogweed had the most significant impact on reducing the number of Heteroptera individuals. Its influence was also observed at the assemblage level. The negative impact of hogweed has been detected despite the application of the first eradication treatments of this plant. Success in eradicating hogweed may be limited due to the spread of the plants from locations where removal is not applied.

Transcriptomes of Zebrafish in Early Stages of Multiple Viral Invasions Reveal the Role of Sterols in Innate Immune Switch-On

Although it is widely accepted that in the early stages of virus infection, fish pattern recognition receptors are the first to identify viruses and initiate innate immune responses, this process has never been thoroughly investigated. In this study, we infected larval zebrafish with four different viruses and analyzed whole-fish expression profiles from five groups of fish, including controls, at 10 h after infection. At this early stage of virus infection, 60.28% of the differentially expressed genes displayed the same expression pattern across all viruses, with the majority of immune-related genes downregulated and genes associated with protein synthesis and sterol synthesis upregulated. Furthermore, these protein synthesis- and sterol synthesis-related genes were strongly positively correlated in the expression pattern of the rare key upregulated immune genes, IRF3 and IRF7, which were not positively correlated with any known pattern recognition receptor gene. We hypothesize that viral infection triggered a large amount of protein synthesis that stressed the endoplasmic reticulum and the organism responded to this stress by suppressing the body's immune system while also mediating an increase in steroids. The increase in sterols then participates the activation of IRF3 and IRF7 and triggers the fish's innate immunological response to the virus infection.

Invaders at the doorstep: Using species distribution modeling to enhance invasive plant watch lists

Watch lists of invasive species that threaten a particular land management unit are useful tools because they can draw attention to invasive species at the very early stages of invasion when early detection and rapid response efforts are often most successful. However, watch lists typically rely on the subjective selection of invasive species by experts or on the use of spotty occurrence records. Further, incomplete records of invasive plant occurrences bias these watch lists towards the inclusion of invasive plant species that may already be present in a land management unit, because the occurrences have not been formally integrated into publicly accessible biodiversity databases. However, these problems may be overcome by an iterative approach that guides more complete detection and compilation of invasive plant species records within land management units. To address issues from unobserved or unrecorded occurrences, we combined predicted suitable habitat from species distribution models and aggregated invasive plant occurrence records to develop ranked watch lists of 146 priority invasive plant species on >4000 land management units from five different administrative types within the United States. Based on this analysis, we determined that on average 84% of priority invasive plants with suitable habitat within a given land management unit were as yet unobserved, and that 41% of those were ‘doorstep species’ – found within 50 miles of the unit boundary yet not detected within the unit. Two case studies, developed in collaboration with staff at U.S. Fish and Wildlife Service Refuges, showed that by combining both habitat suitability models and invasive plant occurrence records, we could identify additional problematic invasive plants that had been previously overlooked. Model-based watch lists of ‘doorstep species’ are useful tools because they can objectively alert land managers to threats from invasive plants with high likelihood of establishment.

Body Length and Craniometrics of Non-Native Raccoons in Two Regions in Middle Japan during Early Invasion Stages

Although the genetic distribution of introduced raccoons (Procyon lotor) in recent years is well known, few studies have examined their morphometrics, especially the relationships between sex and age in the introduced populations. The aim of this study was to describe the morphological characteristics of raccoons from parts of eastern and western Japan during their early invasion stages, focusing on the relationships between body length and the principal component of craniometrics, with region, sex, age class, body length, and body mass index using a regression model. The body length increased more in males than females and in the older age class, supporting the association with intrasexual selection and competition for food resources. Positive relationships for body length and body mass index were found in craniometric analyses, particularly regarding cranial size components, in addition to age class for both sexes, while cranial size also differed between regions for females. The relationship between body length and craniometrics was inconsistent with that of subspecies originating in North America. Given the sympatric distribution of haplotypes of multiple subspecies without reproductive-isolating barriers in North America and in several introduced areas, hybridization must have occurred prior to the introduction or naturalization of this species.

Interspecific Competitions between Frankliniella intonsa and Frankliniella occidentalis on Fresh Lentil Bean Pods and Pepper Plants.

Flower thrips (Frankliniella intonsa, IFT) and west flower thrips (Frankliniella occidentalis, WFT) are often found together on the host plant in China. WFT is an important invasive species that seems to outcompete the native IFT. In order to clarify the interspecific competitions between the two thrips, this study measured the population development of IFT and WFT under sexual and parthenogenetic reproductive modes on two hosts (fresh lentil bean pods with/without honey and pepper plants at seedling/flowering stages) in the laboratory. When reared on fresh lentil bean pods (with/without honey), WFT population size was lower in mixed species populations compared to single species populations but the presence of WFT had nor negative effect on IFT population size. These results were dependent of the reproductive mode. When honey was supplied, the ratio of female-to-male in the progeny of WFT produced under sexual reproductive mode increased significantly in the presence of IFT. On pepper seedlings, mixed populations were more favorable to the population development of IFT at the seedling stage, but more favorable to WFT at the flowering stage. In the early stage of WFT invasion and colonization, the emergence of flowering and honey (nectar) sources may have a positive effect on the population development of WFT.

A nationwide pest risk analysis in the context of the ongoing Japanese beetle invasion in Continental Europe: The case of metropolitan France.

The Japanese beetle, Popillia japonica, is native to Japan and became established in North America in the early twentieth century. The beetle was detected in Europe, first in Italy in 2014 and then in Switzerland in 2017. Metropolitan France is at the forefront of the Japanese beetle threat, due to its geographical proximity to the European populations established in the Piedmont, Lombardy and Ticino regions. An express pest risk analysis for metropolitan France was therefore conducted. The most likely pathways for entry include (i) natural dispersion, (ii) trades of plant products with adherent soil and (iii) hitchhiking behaviour, leading to a high probability of entry. The spread rate of P. japonica was also evaluated as high, resulting from natural spread as well as human activities. Given the absence of significant limiting factors, the potential impacts of P. japonica in France will likely be as important as in its current geographic distribution. Although several sources of uncertainty were highlighted throughout the evaluation, none of them has significant impact on the conclusions of the present express pest risk analysis. Measures to prevent entry, establishment and spread of P. japonica are recommended and include surveillance with pheromone traps and control via integrated pest management strategies. However, most efforts should be concentrated on eradication measures while P. japonica is still in the early stages of invasion.