Biological Invasions最新文献

An unidentified ant species was discovered in the heart of New York City in 2011, which garnered national headlines and created the memorable nickname “ManhattAnt.” New York City is one of the oldest and largest cities in North America and has been the site of introduction for some of North America’s most damaging invasive pests. Nevertheless, there has been little follow up research on the ManhattAnt since its discovery, and it has yet to be formally identified. Here we use genetic and morphological approaches to confirm the identity of the ManhattAnt and characterize its introduced range and colony structure. Results from genetic analyses placed the ManhattAnt within the Lasius emarginatus species complex, and morphological comparisons ruled out closely related species to identify the ManhattAnt as the European ant L. emarginatus with 93–99% certainty depending on the nest sample. Since its initial discovery in the region, the ManhattAnt has become one of the most common ants in New York City and has spread at a rate of 2 km/yr into New Jersey and onto Long Island. Based on the climate it inhabits within its native range, L. emarginatus could expand to cover much of the eastern United states from Massachusetts to Georgia. Although many successful invasive ants display supercoloniality with little aggression between neighboring nests, we found no evidence that L. emarginatus colonies in New York City are supercolonial. Continued monitoring of L. emarginatus is warranted, as it has been increasingly reported as an indoor pest and is known to form mutualisms with honeydew producing pests of street trees.

The Gila topminnow (Poeciliopsis occidentalis) has undergone population recovery actions since being extirpated from much of its historical range in the United States of America (USA) prior to the 1970s. However, it returned to the Santa Cruz River in 2015 independently of these actions, which prompted concerns that a non-native Poeciliopsis lineage had been introduced from Mexico. Some Gila topminnow populations in Mexico are sympatric with P. monacha-occidentalis, which is an exclusively female taxon that originated from historical hybridization between P. occidentalis and headwater livebearer (P. monacha). This hybrid taxon reproduces through hybridogenesis, which is a unique mode of sexual reproduction in which half of one parent’s genome is inherited without recombination. This unique property was leveraged to identify hybridogens among 868 individuals from Arizona, USA using common genetic markers (i.e., nuclear microsatellite and mitochondrial sequence data). We described methods for P. monacha-occidentalis identification and conducted population genetic analysis of Santa Cruz River P. occidentalis populations to infer their possible origins. We concluded that human-mediated introduction was the most probable explanation for the current Santa Cruz River P. occidentalis and P. monacha-occidentalis presence. Contemporary diversity may be explained by four introduction events. Population ancestry estimates indicate that P. monacha-occidentalis may have hybridized with two P. occidentalis lineages in the Santa Cruz River. Variable prevalence of P. monacha-occidentalis was noted in two river sections, but the conservation implications of this hybridization are unclear. Public education, targeted removal of P. monacha-occidentalis, and genetic monitoring could mitigate future introductions and potential negative impacts.

Common milkweed (Asclepias syriaca L.) is a widespread invasive alien forb in dry sandy habitats of Central Europe. It adversely affects native plant and animal communities, but its ecosystem-level effects, particularly on hydrology, are little known. Since milkweed has an extensive, deep root system and large, broad leaves, we assumed a negative effect on the soil moisture content of the hosting ecosystem. Following the before-after control-impact protocol, we first compared the soil moisture content of the top 120 cm of the soil under seven milkweed stands to that of non-invaded reference sites. We then treated half of the stands by mechanically removing all aboveground milkweed biomass and repeated the comparative soil moisture measurements. We found that milkweed stands had significantly drier soils than reference grasslands during the growing season, but the soil under milkweed stands recharged to the level of the references in autumn and winter. However, the amount of moisture needed for this recharge was lost from deeper percolation to groundwater. Milkweed treatment prevented the depletion of moisture during the growing season, saving 21.6 l m⁻² of water on average. Treatment did not affect non-milkweed plant biomass, thus, moisture patterns could fully be attributed to the milkweed stands. Our results reinforce the importance of milkweed suppression in invaded grasslands, as, besides enabling the recovery of the native grassland ecosystem, it promotes groundwater recharge, which is particularly important in the dry regions of Central Europe, currently facing severe aridification due to climate change and unfavourable land use trends.

Sphagneticola trilobata, originally from the tropical regions of the Americas, has successfully invaded the subtropical regions of southern China and displays a tendency to spread towards colder northern regions. The accumulation of anthocyanins in stems under low temperature conditions exhibits strong cold tolerance, and therefore may be one mechanism supporting the northward spread of the species. However, the role and synthesis mechanism of anthocyanins in the stems of S. trilobata when confronted with low temperature stress are still unclear. Field experiments have shown that compared to in summer, the stems of S. trilobata significantly accumulated anthocyanins to cope with winter. Further short-term low-temperature treatments (0 °C) were conducted on red and green stems of S. trilobata, and the results showed that the red stems exhibited lower levels of reactive oxygen species, membrane damage, and chlorophyll fluorescence changes compared to the green stems. In an indoor low-temperature control experiment, it was observed that S. trilobata exhibited significant accumulation of callus in the periderm of its stems compared to S. calendulacea, which subsequently resulted in increased levels of sucrose, glucose, and fructose contents. Furthermore, there was a significantly induced higher levels of abscisic acid and cytokinin in S. trilobata stems under low temperatures. Under the joint regulation of these carbohydrates and hormones, the key structural genes associated with anthocyanins synthesis pathway in S. trilobata stems were more strongly induced compared to S. calendulacea. The upregulation of CHS, CHI, F3H, and DFR gene expression levels in S. trilobata was higher than that of native species, which directly leads to the accumulation of more anthocyanins in the epidermis of the stem of S. trilobata, thereby reducing the degree of oxidative stress and maintaining normal growth under low temperature. In summary, anthocyanins play an important light filtering role in the response of S. trilobatas stem to low temperature stress, which is one of the important mechanisms for its successful invasion into southern China. In the context of global climate change, we need to increase our vigilance against further invasion of S. trilobata into colder inland regions such as temperate regions. This research holds significant theoretical and practical implications for the prevention and control of S. trilobata invasion.

Invasive species represent a threat to many ecosystems but are nearly absent from arctic and subarctic Canada. The treeline town of Churchill, Manitoba, has an unusually high number of invasive species due to the presence of a grain port and railway, but few of these species have spread to the surrounding tundra; for instance, common dandelion (Taraxacum officinale) currently is restricted primarily to town, in contrast with its native congener, Taraxacum lacerum. To investigate whether the distribution of T. officinale is affected by the tendency of buildings to create warm, sheltered microenvironments, we surveyed the abundance of both dandelion species relative to existing structures in town. We established transects extending up to 5 m from each side of 23 buildings, and recorded the number of plants in 50 cm × 50 cm quadrats along each transect. We found that T. officinale performed better on the south sides of buildings, that flowering decreased away from buildings, and that these effects were stronger for T. officinale than the native T. lacerum. Soil temperatures were warmer on the south rather than on the north-facing sides, providing a possible explanation. Our results show that the distribution of T. officinale currently is more influenced by human-created microclimate compared to the abundance of its native relative. However, T. officinale may spread beyond these refuges as the climate continues to warm.

Plant invasions are a widespread and recurring phenomenon that cause significant economic and environmental damage. Invasive alien conifers are weeds that are not only costly to manage, but consistently reinvade after management efforts. Understanding how many seeds survive to germinate is a key part in understanding the weed life cycle puzzle. Here we investigated the contribution that seed predators have on reducing invasive alien conifer seed survival across both invaded and uninvaded habitats in Aotearoa New Zealand. We combined quantitative and qualitative experiments to measure seed predation across invaded and uninvaded habitats, as well as to identify which fauna are the most prolific seed predators. We utilised ex-situ empirical evidence with in-situ observations to provide realistic impacts from different seed predator species. We found that introduced mammals, particularly rodents, were the primary seed predators of invasive conifers. Seed predation pressure was highest in herbicide treated invasive alien conifer forests, indigenous beech forests, and managed pasture containing grazing livestock. Indigenous tussock areas support fewer vertebrate seed predators and as a result are particularly vulnerable to conifer invasion. The majority of seed predation occurs within the first two weeks post-dispersal. These results suggest that introduced mammal control operations, which are essential to protect endemic New Zealand species, will likely result in increasing invasive conifer populations by reducing seed predation pressure. Seed predation varies greatly between habitats, suggesting invasion and reinvasion rates are higher in ungrazed areas of lower forest density that support fewer introduced mammals.

Invasive species are one of the main reasons for the decline in global biodiversity. When it comes to the management of invasive species, stakeholders who are directly involved with this issue play a particularly important role, as they are directly engaged in management and can also influence the public’s perception. This study therefore investigates how different stakeholder groups in Germany perceive invasive species. In total, more than 2200 people were surveyed, belonging to nine different stakeholder groups that are in contact with invasive species (hunters and members in hunting associations, farmers, members of environmental and conservation organizations, members in allotment garden clubs, animal welfare supporters, divers, employees in zoological gardens, administrative employees in the regulatory authority, speleologists). It was found that the number of invasive animal and plant species in Germany was roughly correctly estimated in all groups, but the economic damage caused by invasive species was substantially underestimated. When invasive species were mentioned, mainly conspicuous mammals or plants were listed (e.g. Procyon lotor or Impatiens glandulifera). In all surveyed groups, there was a notable level of interest in invasive species, and they were commonly regarded as environmental issues. While these results offer valuable insights into stakeholders’ perspectives on invasive species, they also highlight the need for improvement. In particular, there is a need for greater education of stakeholders about inconspicuous invasive species, the spread of invasive species and the damage caused by them.

Worldwide declines in critical hymenopteran pollinators, such as bumble bees and honey bees, in recent decades have sparked a surge in research aimed at identifying the factors behind these declines. Among the suspected contributors, infectious diseases have garnered significant attention. In this context, we conduct a comprehensive review of the potential impact of naturalized Palearctic exotic bumble bee species, specifically Bombus terrestris and Bombus ruderatus, on the occurrence of Apicystis bombi in southern South America. Apicystis bombi is a unique apicomplexan protist that belongs to the neogregarines, which as a group exhibit relatively high virulence towards a range of insects. Our review encompasses the available information on its morphology, molecular characteristics, pathology, host range, and geographic distribution. Additionally, we explore three plausible hypotheses, each not necessarily exclusive of the others, in an effort to shed light on the occurrence of A. bombi in South America. These hypotheses include the two classically accepted, but less supported in view of current data (entry via B. terrestris, entry via B. ruderatus), and one postulated for the first time here with arguably better support (pre-existing presence before the introduction of B. terrestris and B. ruderatus, plus the possibility of multiple Apicystis species coexisting). We aim for this review to stimulate interest in this relatively obscure parasitic microbe that affects crucial insect pollinators.

The introduction of Marine Non-Indigenous Species (NIS) poses a significant threat to global marine biodiversity and ecosystems. To mitigate this risk, the Ballast Water Management Convention (BWMC) was adopted by the UN International Maritime Organisation (IMO), setting strict criteria for discharges of ballast water. However, the BWMC permits exemptions for shipping routes operating within a geographical area, known as a Same-Risk-Area (SRA). An SRA can be established in areas where a risk assessment (RA) can conclude that the spread of NIS via ballast water is low relative to the predicted natural dispersal. Despite the BWMC's requirement for RAs to be based on modelling of the natural dispersal of NIS, no standard procedures have been established. This paper presents a methodology utilizing biophysical modelling and marine connectivity analyses to conduct SRA RA and delineation. Focusing on the Kattegat and Øresund connecting the North Sea and Baltic Sea, we examine two SRA candidates spanning Danish and Swedish waters. We provide an example on how to conduct an RA including an RA summary, and addressing findings, challenges, and prospects. Our study aims to advance the development and adoption of consistent, transparent, and scientifically robust SRA assessments for effective ballast water management.

Understanding landscape scale connectivity is an essential component in the management of invasive species since connectivity facilitates their invasion potential. Invasive wild pigs (Sus scrofa) are among the most prolific invaders on the planet, causing billions of dollars in agricultural and environmental damage annually. Newly introduced to Canada in the 1980s, we examined wild pig invasion potential across the northern prairies from western Canada into the currently wild pig-free northern U.S. states. We used GPS collar data collected in the Canadian prairies to quantify resource selection and incorporated results into an electric circuit theory framework to evaluate potential regional landscape connectivity. While available landcover types in this region were dominated by crops and grasslands, wild pigs were predominately located in deciduous forest, crops, and wetlands. Resource selection modelling indicated wild pigs selected deciduous forest and wetlands over other landcover types. These selection tendencies resulted in areas at greater risk of occupation in an intermixture dominated by crops interspersed with waterbodies and deciduous forest fragments, which facilitated movement. Given the pervasiveness of this intermixture across the northern prairies, there was a high potential for invasive wild pigs to move throughout much of the region with areas in southern Saskatchewan and Manitoba, northeastern Montana, North and South Dakota, and western portions of Minnesota being particularly vulnerable. Our work highlights a need for monitoring and science-based response strategies for likely southward spread of this invasive species to prevent or reduce potential crop damage, risks to native species, and disease transmission to humans, pets, livestock, and wildlife.