Dispersal Of Invasive Species Research Articles

UPDATED DISTRIBUTION OF OCTOCORAL Carijoa riisei (DUCHASSAING & MICHELOTTI, 1860) IN BRAZIL INCLUDING ITS FIRST RECORD IN THE STATE OF SERGIPE, NORTHEASTERN BRAZIL

This study recorded, for the first time, the presence of the azooxanthellate colonial octocoral Carijoa riisei (Carijoidae) in the state of Sergipe, Brazil. In September 2021, colonies of C. riisei were observed attached to a floating pier in the estuary of the Vaza-Barris River, in the central region of the Sergipe coastline. These colonies were photographed in situ and collected for confirmation of their morphological identification in the laboratory. Our results represent the first recorded occurrence of Carijoa riisei in the state of Sergipe and contribute to filling a gap in the species distribution along the Brazilian coast. Future studies are necessary to assess the potential impacts of C. riisei on local ecosystems and understand the role of artificial substrates in the dispersal of invasive species.

Ust-Luga Seaport of Russia: Biological Invasions and Resting Stages Accumulation.

This article describes the results of a three-year study of invasive species of aquatic ecosystems in the vicinity of Ust-Luga, the largest Russian seaport in the Baltic. Taking into account the great importance of the participation of marine vessels in the dispersal of invasive species, an experimental study of the seasonality of accumulation of resting stages of aquatic invertebrates in the ballast compartments of a vessel located in the Baltic Sea of the Gulf of Finland was carried out. Experiments show that the time of filling the ballast compartments in late summer and autumn poses the greatest risk for the spread of aquatic invertebrates with ship ballast water. In the Baltic Russian port, 11 invasive species of zooplankton and zoobenthos were found, which comprises 15% of the biodiversity in the samples. Copepoda demonstrated the highest presence of invasive species in class among zooplankton groups (14%) and Malacostraca among benthos groups (80%). Alien species findings correspond to the main vectors of invasive species dispersal for the Baltic Sea: North America, Indochina, and the Ponto-Caspian region.

Personality-dependent passage behaviour of an aquatic invasive species at a barrier to dispersal

Intraspecific variation in personality traits is increasingly recognized as an important determinant of invasion success and is associated with the dispersal ability of several invasive species. However, previous studies have focused on the dispersal of invasive species through continuous habitats, despite the high levels of anthropogenic fragmentation in modern environments. This study investigated how personality influences the behaviour of aquatic invasive species at an anthropogenic barrier to dispersal, using the passage behaviour of American signal crayfish, Pacifastacus leniusculus , at an experimental Crump weir as a model system. Personality was characterized by determining the repeatability of boldness, activity and sociability, with correlations between traits indicating behavioural syndromes, while passage behaviour was quantified as motivation and subsequent ability to pass the weir. Boldness and activity were repeatable and positively correlated, indicating a boldness–activity syndrome. However, sociability was not repeatable and was therefore not classified as a personality trait, potentially as a result of the confounding effects of social hierarchy formation. Bolder individuals tended to be more motivated to pass the weir, although motivation was not related to activity. Few individuals passed the weir, and personality was not related to passage success. This study evidences the presence of behavioural syndromes in signal crayfish and demonstrates that personality can influence the motivation of invasive species to expand their range in a fragmented habitat. Although no relationship with passage success was observed, the higher levels of motivation in bold individuals may lead to differential passage success in natural situations where the time to attempt passage is not constrained by experimental conditions. • Signal crayfish personality and barrier passage behaviour were assessed. • Boldness and activity, but not sociability, were repeatable personality traits. • Crayfish demonstrated a boldness–activity behavioural syndrome. • Bolder crayfish were more motivated to pass the weir, but were not more successful. • Activity and sociability were not related to crayfish passage behaviour.

Influence of Canopy Cover and Meteorological Factors on the Abundance of Bark and Ambrosia Beetles (Coleoptera: Curculionidae) in Avocado Orchards Affected by Laurel Wilt

In the last decade in South Florida, approximately 200,000 avocado trees have succumbed to laurel wilt (LW), a fungal disease vectored by ambrosia beetles. Sanitation (e.g., pruning, stumping, and removal of LW–affected trees) and replanting with young trees are cultural practices currently used by avocado growers to reduce the incidence of LW. Surveillance in these managed orchards suggests a decline in ambrosia beetle abundance, and previous research determined that female flight activity is influenced by light intensity. Therefore, we investigated the effect of three canopy covers (i.e., full canopy, topworked, and new planting) on ambrosia beetle abundance. A total of 28,184 individuals, representing 15 species within Scolytinae and Platypodinae, were captured passively in three LW–affected avocado orchards over a one-year period. Full canopy cover exhibited the highest number of beetles and the lowest light intensity. The opposite was found for topworked and new planting covers. Additionally, we documented the effect of meteorological factors on the flight dispersal of five species known to vector the LW pathogen. The flight activity of Xylosandrus crassiusculus and Xyleborinus saxesenii was highly influenced by abiotic factors (R2 > 0.50), especially solar radiation, whereas the flight of Xyleborus affinis, Xyleborus volvulus, and Xyleborus bispinatus was only partially explained by climatic variables (0.20 < R2 < 0.30). Our results indicate that reducing canopy cover, thereby increasing light intensity, suppresses ambrosia beetle abundance, especially for species associated with the LW pathogen. Abiotic factors play a critical role in the dispersal of invasive species (X. crassiusculus and X. saxesenii), but their effect is less pronounced on native species (X. affinis, X. volvulus, and X. bispinatus). Canopy management alters the microclimatic conditions in avocado orchards, affecting ambrosia beetle abundance and flight activity.

An Integrated Biosecurity Risk Assessment Model (IBRAM) For Evaluating the Risk of Import Pathways for the Establishment of Invasive Species.

An important aspect of analyzing the risk of unwanted organisms establishing in an area is understanding the pathways by which they arrive. Evaluating the risks of these pathways requires use of data from multiple sources, which frequently are uncertain. To address the needs of agencies responsible for biosecurity operations, we present an Integrated Biosecurity Risk Assessment Model (IBRAM) for evaluating the risk of establishment and dispersal of invasive species along trade pathways. The IBRAM framework consists of multiple linked models which describe pest entry into the country, escape along trade pathways, initial dispersal into the environment, habitat suitability, probabilities of establishment and spread, and the consequences of these invasions. Bayesian networks (BN) are used extensively to model these processes. The model includes dynamic BN components and geographic data, resulting in distributions of output parameters over spatial and temporal axes. IBRAM is supported by a web-based tool that allows users to run the model on real-world pest examples and investigate the impact of alternative risk management scenarios, to explore the effect of various interventions and resource allocations. Two case studies are provided as examples of how IBRAM may be used: Queensland fruit fly (Bactrocera tryoni) (Diptera: Tephritidae) and brown marmorated stink bug (Halyomorpha halys) (Hemiptera: Pentatomidae) are unwanted organisms with the potential to invade Aotearoa New Zealand, and IBRAM has been influential in evaluating the efficacy of pathway management to mitigate the risk of their establishment in the country.

Exotic predators are not better biocontrol agents: the harlequin ladybird is not the most voracious in Mexico.

The use of exotic species for pest biocontrol has been a common pathway for introduction and dispersal of invasive species that may have undesired outcomes. Biocontrol agents are believed to be a less damaging alternative than pesticides, but some species may also prey on or parasitize native species or outcompete them for resources. The harlequin ladybird (Harmonia axyridis) is a well-known biocontrol agent originally from Asia that has established invasive populations in 59 countries around the globe. Harlequin ladybirds are generalist predators that in addition to pests prey on an array of different species including other coccinelids’ eggs and larvae. In Mexico, native ladybirds that share ecological requirements with harlequin ladybirds are at risk of being outcompeted and predated upon. The aim of our study was to compare the foraging efficiency of harlequin ladybirds against three species of native coccinelids when preying on aphids. We investigated the foraging behaviour of ladybirds alone and in pairs with a conspecific, a native heterospecific or an exotic heterospecific. We found that the native Cycloneda sanguinea was the species that consumed the most aphids, while Hippodamia convergens was the fastest to find and consume each aphid. Harlequin ladybirds and H. convergens consumed the same number of aphids while P. vittigera consumed less. Conspecific competition was stronger than heterospecific competition. We discuss the suitability of using the exotic invasive harlequin ladybird for aphid biocontrol in comparison with native coccinelids.

Spatially discontinuous relationships between salt marsh invasion and mangrove forest fragmentation

Rapid and large-scale biological invasion results in widespread biodiversity loss and degradation of essential ecosystem services, especially in mangrove forests. Recent evidence suggests that the establishment and dispersal of invasive species may be exacerbated in a fragmented landscape, but the influence of mangrove fragmentation on coastal biological invasion at the landscape scale remains largely unknown. Here, using a derived 10-m-resolution coastal wetland map of the southeastern coast of China, we examine the relationship between the fragmentation of mangrove forests and the magnitude of salt marsh invasion and quantify the geographical variation in this relationship across a climatic gradient. Our results show that mangrove forests with small sizes, large edge proportions, and regular boundary shapes tend to suffer more serious salt marsh invasions than mangrove forests with large sizes, small edges and irregular boundary shapes, indicating a positive correlation between mangrove fragmentation and the magnitude of invasion. In particular, these fragmentation-invasion relationships are shown to be more intensive in the subtropics than in the tropics. Our findings provide the first spatially explicit evidence of the relationships between mangrove fragmentation and biological invasion on a landscape scale and highlight an urgent need for conservation and management actions to improve mangrove connectivity, which will increase the resistance to invasions, especially for small subtropical mangrove forests.

Modeling commodity flow in the context of invasive species spread: Study of Tuta absoluta in Nepal

Trade and transport of goods is widely accepted as a primary pathway for the introduction and dispersal of invasive species. However, understanding commodity flows remains a challenge owing to its complex nature, unavailability of quality data, and lack of systematic modeling methods. A robust network-based approach is proposed to model seasonal flow of agricultural produce and examine its role in pest spread. It is applied to study the spread of Tuta absoluta, a devastating pest of tomato in Nepal. Further, the long-term establishment potential of the pest and its economic impact on the country are assessed. Our analysis indicates that regional trade plays an important role in the spread of T. absoluta. The economic impact of this invasion could range from USD 17–25 million. The proposed approach is generic and particularly suited for data-poor scenarios.

The use of native piscivorous fishes for the eradication of the invasive Chinese Sleeper,Perccottus glenii

The chief aim of invasive species management is to prevent biological invasions by taking measures for suppressing or eradicating potential invaders. Biological control as a management tool is frequently implemented to reduce the population size, adverse ecological impacts, and dispersal of invasive species. The efficacy of biological control measures in managing thePerccottus gleniipopulation was assessed in four small lakes of Lithuania. The biocontrol was carried out by introducing the native piscivorous fishesEsox luciusandPerca fluviatilisinto the invaded water bodies for two successive reproductive seasons. The stocking of these fishes led to an instant reduction inP. gleniiabundances, and the outcome of the repeated stocking was complete disappearance of the species from the water bodies investigated. Our study proves that native predator fishes can be successfully used for eradicating well-establishedP. gleniipopulations in small eutrophic lakes. We hope the current study results will contribute to developing risk-commensurate methodologies for the control of invasiveP. gleniipopulations in small water bodies.

Reproductive strategy and gamete development of an invasive fanworm, Sabella spallanzanii (Polychaeta: Sabellidae), a field study in Gulf St Vincent, South Australia.

Several reproductive strategies have been identified as key factors that contribute to the establishment and dispersal of invasive species in new environments. These strategies include early maturity, high reproductive capacity and flexibility in timing of reproduction. It is therefore critical to investigate the reproductive biology of target exotic species to understand their potential for population increase and invasive spread, and to inform management control strategies. The European fanworm, Sabella spallanzanii (Gmelin 1791), has established invasive populations along the southern coast of Australia. Gamete development and reproductive periodicity of this worm were investigated in two populations in Gulf St Vincent in South Australia over a 1 year period (July 2012 to June 2013). Samples of worms were collected monthly and dissected for histological analysis. Most individuals reached reproductive maturity at 70 mm body length (thorax and abdomen). Individuals from both populations contained mature and developing gametes year-round and a distinct spawning season was not observed. This may indicate sustained spawning by the population over the year, which provides a constant supply of new recruits to the area. Body length and egg size of worms from these populations were smaller than conspecifics in its native range and other invasive locations. Reproduction and development of S. spallanzanii differs not only between native and invasive locations, but also within invasive locations. This study has shown that S. spallanzanii exhibits a higher phenotypic plasticity and reproductive flexibility than previously known.

Nematodes network too: diversity, abundance and dispersal via plant produce trade networks

The dispersal of invasive species, such as plant pests, can have major economic, environmental and social impacts worldwide. Movement of plant pests from farms to both foreign and domestic markets is facilitated by trade networks, such as plant produce trade networks. While many potential pathways of invasive plant pest entry are regulated, few studies have examined the diversity, abundance and dispersal of soil microorganisms, such as nematodes, on plant produce while en route between origin and destination to quantify the risk of invasive plant pest introductions via these pathways. Here it is shown that a large range and number of live nematodes are dispersing locally and nationally via plant produce trade networks, with the potential to also move internationally. Up to 98% of samples tested carried free‐living nematodes and up to 40% carried plant‐parasitic forms. Diversity of nematodes varied between countries and regions, and numbers on samples generally decreased with increasing distance from the farm to market. These findings may have implications for plant biosecurity surveillance as well as human health. Moreover, nematodes provide a model for other potentially invasive species dispersing via plant produce trade networks.

Evaluating the distribution of invasive woody vegetation around riparian corridors in relation to land use

Invasive species have been causing important and irreversible impacts to native species and communities of ecosystems. They distort ecosystem functions by degrading forest lands, wetlands, and agricultural habitats and replace the native vegetation and reduce biodiversity, forest productivity, and suitable wildlife habitat. To address disturbances caused by invasive species occurrence, further information is needed regarding the occurrence, extent, and dispersal of invasive species and how land use may increase the spread of these species. The objective of this study was to find the frequency and dominance of three invasive species common to riparian areas of east Alabama: Ligustrum sinense (Chinese privet), Elaeagnus pungens (silverthorn), and Triadica sebifera (Chinese tallow tree). Surveys of these species in riparian forests in and around Auburn, Alabama were conducted to show the relative extent of these shrubs and their relation to urban land use. It was expected to see the highest levels of invasive species in the city center with decreasing levels radiating outward into rural areas. Another objective was how urban land use may affect the presence-absence and prevalence of these non-native plant species within study sites. The results showed that around the city center and suburban lands, cover of both Chinese privet and silverthorn tended to increase. In contrast, Chinese tallow tree density percent cover showed an opposite trend with landscapes close to city center often having slightly less cover. This study shows that urban land use may be an important association with distribution of invasive plant species.

Range estimates and habitat use of invasive Silver Carp (Hypophthalmichthys molitrix): evidence of sedentary and mobile individuals

Unregulated rivers provide unobstructed corridors for the dispersal of both native and invasive species. We sought to evaluate range size and habitat use of an invasive species (Silver Carp, Hypophthalmichthys molitrix) in an unimpounded river reach (Wabash River, IN), to provide insights into the dispersal of invasive species and their potential overlap with native species. We hypothesized that range size would increase with fish length, be similar among sexes, and vary annually while habitats used would be deeper, warmer, lower velocity, and of finer substrate. Silver Carp habitat use supported our hypotheses but range size did not vary with sex or length. 75% home range varied annually, suggesting that core areas occupied by individuals may change relative to climate-based factors (e.g., water levels), whereas broader estimates of range size remained constant across years. Ranges were often centered on landscape features such as tributaries and backwaters. Results of this study indicate habitat and landscape features as potential areas where Silver Carp impacts on native ecosystems may be the greatest. Observed distribution of range sizes indicates the presence of sedentary and mobile individuals within the population. Mobile individuals may be of particular importance as they drive the spread of the invasive species into new habitats.

Population dynamics of two invasive amphipods in the Southwestern Atlantic: Monocorophium acherusicum and Ericthonius punctatus (Crustacea)

ABSTRACTHarbours are important sites for the containment and dispersal of invasive species throughout the world, so the study of life history traits of species is important to understand the success of their invasion and their potential effects on the habitat. In recent years several invasive species have been reported in Argentinian harbours; however, studies of the ecology and life history of these species are scarce. We studied the population dynamics and reproductive biology of Monocorophium acherusicum and Ericthonius punctatus, in order to update the published information on the introduced amphipods in Mar del Plata harbour. Both species showed a seasonal pattern characterized by high densities in warmer months, related to the highest reproductive activity and the increase of recruitment in summer and early autumn, and lower densities in the cold season. The sex ratio was always female-biased and the number of eggs carried by females was positively correlated to the size. The present study suggests that both species have colonized Mar del Plata harbour successfully, showing viable populations (cohorts of juveniles, males, females and ovigerous females). This work provides the basis for monitoring the impact generated by introduced amphipods over the existing fauna.

Spatial patterns and spread of exotic earthworms at local scales

Given the substantial impacts of non-native species on invaded systems, an understanding of the rates and spatial patterns of invasive spread is critical. Spread may vary across spatial scales, with dispersal of invasive species occurring both via diffusive spread at local sites and long-distance jump dispersal at larger scales. Research on earthworm invasions in North American forests has focused on patterns of spread across landscapes, with less examination of spread at local sites. We sampled the exotic earthworm Dendrobaena octaedra (Savigny, 1826) on 500 m × 500 m grids at three sites in the boreal forest of northeastern Alberta in 2006 and again in 2012–2013 to examine distributional changes over time. Earthworms spread farther from roads (the presumed site of initial introduction) over time, and spatial patterns at our sites suggest transport by vehicles and waterways are key vectors of dispersal at the local level. Spread was estimated to be occurring at a rate of at least 17.9 m/year. Our study indicates that both diffusive spread and jump dispersal of earthworms can be important at local scales and that local diffusive spread may be substantially higher than previously estimated.

Dispersal of invasive species by drifting

Abstract Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present study shows that high abundances of invasive species drift in the headstream of the river Rhine. Dikerogammarus villosus and Chelicorophium curvispinum represented up to 90% of the total of drifting macroinvertebrates. Drift activity shows seasonal and diel patterns. Most species started drifting in spring and were most abundant in the water column during the summer period. Drift activity was very low during the winter period. Diel patterns were apparent; most species, including D. villosus, drifted during the night. Drifting macroinvertebrates colonised stony substrate directly from the water column. D. villosus generally colonised the substrate at night, while higher numbers of C. curvispinum colonised the substrate during the day. It is very likely that drifting functions as a dispersal mechanism for crustacean invaders. Once waterways are connected, these species are no longer necessarily dependent on dispersal vectors other than drift for extending their distribution range.

Conundrums of a complex vector for invasive species control: a detailed examination of the horticultural industry

Historically the horticultural industry has transformed the US landscape through intentional cultivar introductions and unintentional introductions of weeds, insects and plant diseases. While it has been demonstrated that the horticultural industry, in particular the ornamental subsector, is an important vector for the introduction and dispersal of invasive species, known invasive plants continue to be sold while new cultivars are introduced at an ever increasing rate. This study examines the horticultural trade as a vector for invasive species, its agents, and characterizes the complexity of the distribution channel. Numerous factors have contributed to the recent expansion in marketed cultivars, including technological, industry growth, and marketing developments. The result has been an increased and sophisticated consumer demand with a corresponding aggressive scouring of the planet for new crops, many of which are introduced into the market without sufficient testing for invasive tendencies. Traditional approaches to invasive horticultural crop control (regulation, self-regulation), which target players in the distribution channel before and/or after cultivar release, have had limited effectiveness and buy-in because these approaches do not address the industry’s complexities and economic incentives. Involvement and education of consumers may provide better oversight outcomes by addressing the moral hazard problem while acknowledging the key characteristics of the industry.

Simulating the effect of invasive species on native freshwater mussel communities

The dispersion of invasive species is a serious problem worldwide. In North America in particular, the introduction of the zebra mussel (Dreissena polymorpha) has caused millions of dollars in economic losses and environmental damage. This paper uses ecohydraulics modeling to analyze the effects of zebra mussels on native freshwater mussel communities (unionids) in the Upper Mississippi River (UMR), USA. The model takes into account environmental forcing functions and individual mussel interactions in the form of food competition. First, hydrodynamic transport of incoming zebra mussel larvae was simulated to assess their colonization patterns on unionids. Next, population growth at various food availabilities was computed. Simulated zebra mussel densities were within the range observed in published studies and survival rates of unionids coincided with reported values for an upstream reach of the UMR. These results suggest that these two families of species may coexiste in the UMR, although the sharp decline in the unionid populations may eventually result in extirpation due to unsuccessful egg fertilization. This model provides the means for better understanding the interaction between native and invasive freshwater mussel species and it may be a valuable tool supporting the development of appropriate conservation strategies for unionids.

Fractional Reproduction-Dispersal Equations and Heavy Tail Dispersal Kernels

Reproduction-Dispersal equations, called reaction-diffusion equations in the physics literature, model the growth and spreading of biological species. Integro-Difference equations were introduced to address the shortcomings of this model, since the dispersal of invasive species is often more widespread than what the classical RD model predicts. In this paper, we extend the RD model, replacing the classical second derivative dispersal term by a fractional derivative of order 1<alpha</=2. Fractional derivative models are used in physics to model anomalous super-diffusion, where a cloud of particles spreads faster than the classical diffusion model predicts. This paper also establishes a connection between the new RD model and a corresponding ID equation with a heavy tail dispersal kernel. The general theory developed here accommodates a wide variety of infinitely divisible dispersal kernels that adapt to any scale. Each one corresponds to a generalised RD model with a different dispersal operator. The connection established here between RD and ID equations can also be exploited to generate convergent numerical solutions of RD equations along with explicit error bounds.

Relative Importance of Wetland type Versus Anthropogenic Activities in Determining Site Invasibility

We assessed wetland invasibility by conducting surveys of three wetlands in each of five categories (riverine, depression, lacustrine fringe, mineral flat, and seepage slope). Invasibility was measured as the number of invasive species present, percent of plant species classified as invasive, percent cover of invasive plants, and percent of total cover represented by invasive species. The working hypothesis for this study was that certain types of wetlands (e.g., lacustrine fringe and riverine) would be more prone to invasion than others (spring-seep/slope wetlands or mineral flat wetlands). No significant differences were found among wetland types in any of the invasion metrics evaluated, despite high average invasibility in the riverine and lacustrine fringe categories. However, invasion was correlated very strongly with a qualitative index of anthropogenic modification to the surrounding landscape. A probable result of the substantial influence of human activities on wetland invasion in this study was that effects potentially attributable to greater opportunity for dispersal in certain types of wetlands were obscured. Another factor that likely contributed to the lack of differences among wetland types was the high variability in human activities observed among wetlands within types. These results further highlight the overwhelming contributions of anthropogenic habitat modification and human-assisted dispersal of invasive species to the currently observed homogenization of natural ecosystems.