Global Establishment Risk of Economically Important Fruit Fly Species (Tephritidae)

The global invasion of Tephritidae (fruit flies) attracts a great deal of attention in the field of plant quarantine and invasion biology because of their economic importance. Predicting which one in hundreds of potential invasive fruit fly species is most likely to establish in a region presents a significant challenge, but can be facilitated using a self organising map (SOM), which is able to analyse species associations to rank large numbers of species simultaneously with an index of establishment. A global presence/absence dataset including 180 economically significant fruit fly species in 118 countries was analysed using a SOM. We compare and contrast ranked lists from six countries selected from each continent, and also show that those countries geographically close were clustered together by the SOM analysis because they have similar fruit fly assemblages. These closely clustered countries therefore represent greater threats to each other as sources of invasive fruit fly species. Finally, we indicate how this SOM method could be utilized as an initial screen to support prioritizing fruit fly species for further research into their potential to invade a region.     

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.     

Geographic profiling as a novel spatial tool for targeting the control of invasive species

Geographic profiling (GP) was originally developed as a statistical tool in criminology, where it uses the spatial locations of linked crimes (for example murder, rape or arson) to identify areas that are most likely to include the offender's residence. The technique has been successful in this field, and is now widely used by police forces and investigative agencies around the world. Here, we show that this novel technique can also be used to identify source populations of invasive species, using their current locations as input, as a prelude to targeted control measures. Our study has two main parts. In the first, we use computer simulations to compare GP to other simple measures of spatial central tendency (centre of minimum distance, spatial mean, spatial median), as well as to a more sophisticated single parameter kernel density model. GP performs significantly better than any of these other approaches. In the second part of the study, we analyse historical data from the Biological Records Centre (BRC) for 53 invasive species in Great Britain, ranging from marine invertebrates to woody trees, and from a wide variety of habitats (including littoral habitats, woodland and man‐made habitats). For 52 of these 53 data sets, GP outperforms spatial mean, spatial median and centre of minimum distance as a search strategy, particularly as the number of sources (or potential sources) increases. We analyse one of these data sets, for Heracleum mantegazzianum, in more detail, and show that GP also outperforms the kernel density model. Finally, we compare fitted parameter values between different species, groups and habitat types, with a view to identifying general values that might be used for novel invasions where data are lacking. We suggest that geographic profiling could potentially form a useful component of integrated control strategies relating to a wide variety of invasive species.     

Can Global Weed Assemblages Be Used to Predict Future Weeds?

Predicting which plant taxa are more likely to become weeds in a region presents significant challenges to both researchers and government agencies. Often it is done in a qualitative or semi-quantitative way. In this study, we explored the potential of using the quantitative self-organising map (SOM) approach to analyse global weed assemblages and estimate likelihoods of plant taxa becoming weeds before and after they have been moved to a new region. The SOM approach examines plant taxa associations by analysing where a taxon is recorded as a weed and what other taxa are recorded as weeds in those regions. The dataset analysed was extracted from a pre-existing, extensive worldwide database of plant taxa recorded as weeds or other related status and, following reformatting, included 187 regions and 6690 plant taxa. To assess the value of the SOM approach we selected Australia as a case study. We found that the key and most important limitation in using such analytical approach lies with the dataset used. The classification of a taxon as a weed in the literature is not often based on actual data that document the economic, environmental and/or social impact of the taxon, but mostly based on human perceptions that the taxon is troublesome or simply not wanted in a particular situation. The adoption of consistent and objective criteria that incorporate a standardized approach for impact assessment of plant taxa will be necessary to develop a new global database suitable to make predictions regarding weediness using methods like SOM. It may however, be more realistic to opt for a classification system that focuses on the invasive characteristics of plant taxa without any inference to impacts, which to be defined would require some level of research to avoid bias from human perceptions and value systems.     

Modelling the Arrival of Invasive Organisms via the International Marine Shipping Network: A Khapra Beetle Study

Species can sometimes spread significant distances beyond their natural dispersal ability by anthropogenic means. International shipping routes and the transport of shipping containers, in particular are a commonly recognised pathway for the introduction of invasive species. Species can gain access to a shipping container and remain inside, hidden and undetected for long periods. Currently, government biosecurity agencies charged with intercepting and removing these invasive species when they arrive to a county's border only assess the most immediate point of loading in evaluating a shipping container's risk profile. However, an invasive species could have infested a container previous to this point and travelled undetected before arriving at the border. To assess arrival risk for an invasive species requires analysing the international shipping network in order to identify the most likely source countries and the domestic ports of entry where the species is likely to arrive. We analysed an international shipping network and generated pathway simulations using a first-order Markov chain model to identify possible source ports and countries for the arrival of Khapra beetle (Trogoderma granarium) to Australia. We found Kaohsiung (Taiwan) and Busan (Republic of Korea) to be the most likely sources for Khapra beetle arrival, while the port of Melbourne was the most likely point of entry to Australia. Sensitivity analysis revealed significant stability in the rankings of foreign and Australian ports. This methodology provides a reliable modelling tool to identify and rank possible sources for an invasive species that could arrive at some time in the future. Such model outputs can be used by biosecurity agencies concerned with inspecting incoming shipping containers and wishing to optimise their inspection protocols.     

Profiling invasive fish species: the importance of phylogeny and human use

Understanding the ecological differences between native and invasive species is of considerable scientific and practical interest. We examined such differences between native and invasive inland fish species from the Iberian Peninsula in order to analyse the importance of phylogenetic correction and variability (in addition to central tendency). We collected 26 quantitative and qualitative variables on the ecology, life‐history traits and human use of the 69 inland fish species of the Iberian Peninsula, including native, invasive and migratory species. The taxonomic distribution of invasive fish species deviated significantly from world freshwater richness and in contrast to native species, invasive fish belongs to only five taxonomic orders but to a wide spectrum of families not native to the Iberian Peninsula. Because the life‐history traits were highly dependent on taxonomy, the results, with or without applying phylogenetic methods, differed and after accounting for phylogeny, invasive species displayed higher and wider latitude in general and a different reproductive season mainly among salmonids and cyprinids. Human use was also significantly different between native and invasive fish species and produced more variability in life‐history traits of invasive species and uneven taxonomic distribution because of the high diversity of species introduced. We show that accounting for taxonomy and studying variability in addition to central tendency is important in the comparison of life‐history traits between native and invasive species.     

Emergence and accumulation of novel pathogens suppress an invasive species

Emerging pathogens are a growing threat to human health, agriculture and the diversity of ecological communities but may also help control problematic species. Here we investigated the diversity, distribution and consequences of emerging fungal pathogens infecting an aggressive invasive grass that is rapidly colonising habitats throughout the eastern USA. We document the recent emergence and accumulation over time of diverse pathogens that are members of a single fungal genus and represent multiple, recently described or undescribed species. We also show that experimental suppression of these pathogens increased host performance in the field, demonstrating the negative effects of emerging pathogens on invasive plants. Our results suggest that invasive species can facilitate pathogen emergence and amplification, raising concerns about movement of pathogens among agricultural, horticultural, and wild grasses. However, one possible benefit of pathogen accumulation is suppression of aggressive invaders over the long term, potentially abating their negative impacts on native communities.     

The annual invasive plant Impatiens glandulifera reduces hyphal biomass of soil fungi in deciduous forests

Soil fungi play a crucial role in ecosystem functioning and there is increasing evidence that exotic plants invading forests can affect soil fungal communities. We examined potential effects of the invasive plant Impatiens glandulifera on hyphal biomass of ectomycorrhizal fungi, their genetic diversity and the diversity of other soil fungi in deciduous forests in Switzerland. We compared invaded patches with patches where I. glandulifera had been removed, by establishing pairs of 3-m long transect lines at the edge of seven areas of either type. Along the transects we assessed the length of ectomycorrhizal fungal hyphae using the ‘ingrowth mesh bag method’, and used terminal restriction fragment length polymorphism (T-RFLP) analysis to examine fungal genetic diversity. The invasive plant reduced fungal hyphal biomass by 30–80%: the reduction was largest in the centre of the patch. I. glandulifera did not alter fungal richness, but affected the composition of fungal communities. This is probably the result of a decrease of mycorrhizal fungi, coupled with an increase of saprotrophic fungi. Our findings demonstrate the adverse impacts of an annual invasive plant species on both fungal hyphal biomass and the composition of soil fungal communities. This may negatively affect forest nutrient and carbon cycling, soil stability and the functionality of the fungal community, with major consequences for forest ecosystem functioning.     

DNA barcoding of invasive plants in China: A resource for identifying invasive plants

Invasive plants have aroused attention globally for causing ecological damage and having a negative impact on the economy and human health. However, it can be extremely challenging to rapidly and accurately identify invasive plants based on morphology because they are an assemblage of many different families and many plant materials lack sufficient diagnostic characteristics during border inspections. It is therefore urgent to evaluate candidate loci and build a reliable genetic library to prevent invasive plants from entering China. In this study, five common single markers (ITS, ITS2, matK, rbcL and trnH‐psbA) were evaluated using 634 species (including 469 invasive plant species in China, 10 new records to China, 16 potentially invasive plant species around the world but not introduced into China yet and 139 plant species native to China) based on three different methods. Our results indicated that ITS2 displayed largest intra‐ and interspecific divergence (1.72% and 91.46%). Based on NJ tree method, ITS2, ITS, matK, rbcL and trnH‐psbA provided 76.84%, 76.5%, 63.21%, 52.86% and 50.68% discrimination rates, respectively. The combination of ITS + matK performed best and provided 91.03% discriminatory power, followed by ITS2 + matK (85.78%). For identifying unknown individuals, ITS + matK had 100% correct identification rate based on our database, followed by ITS/ITS2 (both 93.33%) and ITS2 + matK (91.67%). Thus, we propose ITS/ITS2 + matK as the most suitable barcode for invasive plants in China. This study also demonstrated that DNA barcoding is an efficient tool for identifying invasive species.     

Global patterns of fern species diversity: An evaluation of fern data in GBIF

Despite that several studies have shown that data derived from species lists generated from distribution occurrence records in the Global Biodiversity Information Facility (GBIF) are not appropriate for those ecological and biogeographic studies that require high sampling completeness, because species lists derived from GBIF are generally very incomplete, Suissa et al. (2021) generated fern species lists based on data with GBIF for 100 km × 100 km grid cells across the world, and used the data to determine fern diversity hotspots and species richness–climate relationships. We conduct an evaluation on the completeness of fern species lists derived from GBIF at the grid–cell scale and at a larger spatial scale, and determine whether fern data derived from GBIF are appropriate for studies on the relations of species composition and richness with climatic variables. We show that species sampling completeness of GBIF is low (<40%) for most of the grid cells examined, and such low sampling completeness can substantially bias the investigation of geographic and ecological patterns of species diversity and the identification of diversity hotspots. We conclude that fern species lists derived from GBIF are generally very incomplete across a wide range of spatial scales, and are not appropriate for studies that require data derived from species lists in high completeness. We present a map showing global patterns of fern species diversity based on complete or nearly complete regional fern species lists.     

Land-cover and climate factors contribute to the prevalence of the ectoparasitic fungus Laboulbenia formicarum in its invasive ant host Lasius neglectus

Understanding the distribution of parasites is crucial for biodiversity conservation. Here, we studied the distribution of the ectoparasitic fungus Laboulbenia formicarum in native and invasive Lasius ants in a 2000 km² area. We screened over 16,000 ant workers in 478 colonies of five different species. We found that Lab. formicarum was rare in native Lasius species but infected 58% of the colonies of the invasive species Las. neglectus. At landscape scale, Lab. formicarum presence could not be explained by geographic and genetic distances between Las. neglectus colonies but was associated with hotter and dryer climatic conditions and its prevalence in colonies increased with urbanization. Within infected colonies, fungal prevalence varied from 0 to 100 percent within meters and was negatively correlated with impervious ground cover. In a changing world, our findings emphasize the importance of land-use and climatic factors in shaping the distribution and prevalence of fungal parasites.     

Application of a self-organizing map to select representative species in multivariate analysis: A case study determining diatom distribution patterns across France

Ecological communities consist of a large number of species. Most species are rare or have low abundance, and only a few are abundant and/or frequent. In quantitative community analysis, abundant species are commonly used to interpret patterns of habitat disturbance or ecosystem degradation. Rare species cause many difficulties in quantitative analysis by introducing noises and bulking datasets, which is worsened by the fact that large datasets suffer from difficulties of data handling. In this study we propose a method to reduce the size of large datasets by selecting the most ecologically representative species using a self organizing map (SOM) and structuring index (SI). As an example, we used diatom community data sampled at 836 sites with 941 species throughout the French hydrosystem. Out of the 941 species, 353 were selected. The selected dataset was effectively classified according to the similarities of community assemblages in the SOM map. Compared to the SOM map generated with the original dataset, the community pattern gave a very similar representation of ecological conditions of the sampling sites, displaying clear gradients of environmental factors between different clusters. Our results showed that this computational technique can be applied to preprocessing data in multivariate analysis. It could be useful for ecosystem assessment and management, helping to reduce both the list of species for identification and the size of datasets to be processed for diagnosing the ecological status of water courses.     

Preadapted for invasiveness: do species traits or their plastic response to shading differ between invasive and non‐invasive plant species in their native range?

Aim Species capable of vigorous growth under a wide range of environmental conditions should have a higher chance of becoming invasive after introduction into new regions. High performance across environments can be achieved either by constitutively expressed traits that allow for high resource uptake under different environmental conditions or by adaptive plasticity of traits. Here we test whether invasive and non‐invasive species differ in presumably adaptive plasticity. Location Europe (for native species); the rest of the world and North America in particular (for alien species). Methods We selected 14 congeneric pairs of European herbaceous species that have all been introduced elsewhere. One species of each pair is highly invasive elsewhere in the world, particularly so in North America, whereas the other species has not become invasive or has spread only to a limited degree. We grew native plant material of the 28 species under shaded and non‐shaded conditions in a common garden experiment, and measured biomass production and morphological traits that are frequently related to shade tolerance and avoidance. Results Invasive species had higher shoot–root ratios, tended to have longer leaf‐blades, and produced more biomass than congeneric non‐invasive species both under shaded and non‐shaded conditions. Plants responded to shading by increasing shoot–root ratios and specific leaf area. Surprisingly, these shade‐induced responses, which are widely considered to be adaptive, did not differ between invasive and non‐invasive species. Main conclusions We conclude that high biomass production across different light environments pre‐adapts species to become invasive, and that this is not mediated by plasticities of the morphological traits that we measured.     

An invasive wetland grass primes deep soil carbon pools

Understanding the processes that control deep soil carbon (C) dynamics and accumulation is of key importance, given the relevance of soil organic matter (SOM) as a vast C pool and climate change buffer. Methodological constraints of measuring SOM decomposition in the field prevent the addressing of real‐time rhizosphere effects that regulate nutrient cycling and SOM decomposition. An invasive lineage of Phragmites australis roots deeper than native vegetation (Schoenoplectus americanus and Spartina patens) in coastal marshes of North America and has potential to dramatically alter C cycling and accumulation in these ecosystems. To evaluate the effect of deep rooting on SOM decomposition we designed a mesocosm experiment that differentiates between plant‐derived, surface SOM‐derived (0–40 cm, active root zone of native marsh vegetation), and deep SOM‐derived mineralization (40–80 cm, below active root zone of native vegetation). We found invasive P. australis allocated the highest proportion of roots in deeper soils, differing significantly from the native vegetation in root : shoot ratio and belowground biomass allocation. About half of the CO₂ produced came from plant tissue mineralization in invasive and native communities; the rest of the CO₂ was produced from SOM mineralization (priming). Under P. australis, 35% of the CO₂ was produced from deep SOM priming and 9% from surface SOM. In the native community, 9% was produced from deep SOM priming and 44% from surface SOM. SOM priming in the native community was proportional to belowground biomass, while P. australis showed much higher priming with less belowground biomass. If P. australis deep rooting favors the decomposition of deep‐buried SOM accumulated under native vegetation, P. australis invasion into a wetland could fundamentally change SOM dynamics and lead to the loss of the C pool that was previously sequestered at depth under the native vegetation, thereby altering the function of a wetland as a long‐term C sink.     

深圳市入侵植物区系与风险分布

外来植物入侵现象随着城市化的推进在各地愈演愈烈,严重影响城市的生态系统稳定和社会经济发展。在深圳陆域优势植被普查的基础上开展,对深圳全市的入侵植物分布、来源、入侵途径、风险等进行调查分析,为深圳的入侵植物防治提供技术支撑。基础数据采用高分辨率遥感影像与地面实地观察结合的方法普查得到;并通过文献分析法对植物种类基础数据按研究要求进行筛选、提取、分析;创新性的引入斑块入侵风险计算方法和入侵植物种群风险计算方法,经计算得出深圳市范围内的入侵植物风险分布现状与高风险入侵植物种群。结果表明：(1)参照《中国外来入侵植物名录》标准,深圳市陆域群落优势植物共有入侵植物63科200属258种,且以豆科、菊科、禾本科植物为主;其中36种为林业部门、生态环境部门、农业农村部和海关明确的官方认定且需要严格管控的入侵物种;(2)单种科和少种科占比较高,共占比87.3%,大型科虽然占比仅4.8%,却包含了共计106种,占入侵植物总种数41.1%;单种属在深圳入侵植物区系中占绝对优势,占比83.5%,远高于其他类型之和;中型属中,属种比为1∶6;(3)热带区系属性非常明显,热带分布科共计35科,占总科数的92.1...     

Climate change and the potential distribution of an invasive shrub, Lantana camara L

The threat posed by invasive species, in particular weeds, to biodiversity may be exacerbated by climate change. Lantana camara L. (lantana) is a woody shrub that is highly invasive in many countries of the world. It has a profound economic and environmental impact worldwide, including Australia. Knowledge of the likely potential distribution of this invasive species under current and future climate will be useful in planning better strategies to manage the invasion. A process-oriented niche model of L. camara was developed using CLIMEX to estimate its potential distribution under current and future climate scenarios. The model was calibrated using data from several knowledge domains, including phenological observations and geographic distribution records. The potential distribution of lantana under historical climate exceeded the current distribution in some areas of the world, notably Africa and Asia. Under future scenarios, the climatically suitable areas for L. camara globally were projected to contract. However, some areas were identified in North Africa, Europe and Australia that may become climatically suitable under future climates. In South Africa and China, its potential distribution could expand further inland. These results can inform strategic planning by biosecurity agencies, identifying areas to target for eradication or containment. Distribution maps of risk of potential invasion can be useful tools in public awareness campaigns, especially in countries that have been identified as becoming climatically suitable for L. camara under the future climate scenarios.     

Rubbish dumps as invasive plant epicentres

It is widely known that disturbed areas favour plant species invasion. However, the presence and impacts of introduced plants at rubbish dumps and landfills are less clear. We conducted a literature review to evaluate current knowledge on introduced plants species at these sites to assess their potential role as invasion epicentres. Most of the studies we found (91%) were observational and only described plant species presence in multiple landscapes, including rubbish dumps or landfills. A minority of studies (<?20%) specifically focused on plant species at these sites but did not evaluate their potential as invasion epicentres. The 215 introduced plant species belonging to 57 families recorded at rubbish dumps or landfills underestimates true numbers given that most studies do not report the full list of species. Most species are invasive (>?95%) and included in the Global Invasive Species Database or the DAISIE list. One species, Arundo donax, is among the 100 worst invasive species in the world and eight more are listed among the 100 worst invasive species in Europe. Invasive species present at these sites may alter fire regimens, produce toxic and allergen effects, outcompete native species, act as agricultural pests, and lead to economic losses. Our results are a first step to include rubbish dumps and landfills in the agenda of ecologists and managers that study invasive species, especially since compost from these sites are now being used in agricultural practices, thus possibly spreading invasive species propagules to distant locations.     

Abundance of invasive peacock bass increases with water residence time of reservoirs in southeastern Brazil

Neotropical freshwater ecosystems are experiencing a great expansion in the number of invasive species, which is especially alarming since this region harbours 30% of the world’s fish biodiversity with high levels of endemism. We aimed to evaluate the main predictors of peacock basses (Cichla spp.) abundance outside their native range, which are the Amazon and Tocantins-Araguaia river basins. We used multivariate ordination techniques and multimodel inference to analyse peacock basses abundance in twelve reservoirs of the Paraíba do Sul river basin, southeastern Brazil. Interestingly, reservoirs at higher (southernmost) latitudes, located in more populated areas, had higher water temperature and lower turbidity, due to increased water residence time, and these three variables were also positively correlated with abundance of this warm-water invasive fish. Habitat structure was less important in explaining peacock basses abundance, which was not significantly related to biotic factors (fish species richness and time since peacock basses introduction). We hypothesize that the observed effects of reservoir management on limnological features and peacock bass abundance, particularly water residence time (as a mediator of temperature and turbidity), may apply to other Neotropical basins and could influence the impact of this invader.     

重视侵袭性真菌病的诊治

随着免疫抑制剂、广谱抗菌素、器官移植和侵袭性操作应用的增加,侵袭性真菌病的发生率也相应地增加。临床医生的误诊误治,更加重了这种倾向。要纠正这种倾向,必须提高对侵袭性真菌病的认识水平。分清真菌相关的概念,了解微生物学特性,熟悉流行病学现状和趋势,重视早期诊断尤其是疑似线索,对实现真正意义上的分层治疗是非常重要的。