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Invasive species pose a significant threat to biodiversity, particularly when local communities view them positively, presenting a key challenge for effective control. Acacia trees, native to Australia, have been introduced in various regions worldwide, including Chile. Our study focuses on the geographical distribution, perceptions, memories, and willingness to control Acacia species, especially dealbata and A. melanoxylon, in a basin in Central Chile. Landsat 8 OLI/TIRS images captured during the tree’s flowering season were employed to analyse the species’ distribution. We conducted an open survey with 81 participants to gauge the community’s perceptions and memories of these tree species. A binomial model was constructed, incorporating social and geographic variables, and analyses were conducted to assess the significance of memories. We found in the basin 613.200 hectares of Acacia , constituting 1.7% of the analysed basin . 59 sentences of expressing memories were analyzed; most of them were positive towards Acacia . 45.68% of interviewed believed that Acacia is a native tree, and 35.8% recognized it as a harmful species. Despite 72.84% considering Acacia a useful tree, 60.49% expressed a willingness to limit its expansion. Counterintuitively, the willingness to control the species was positively correlated with its use. The use of Acacia also proved positive interaction with the perception that it is expanding and is harmful. Younger and moderately educated participants exhibited more interest in controlling Acacia trees, and older participants when these variables interacted with their use. We interpret these results as an indication that individuals with greater knowledge of Acacia possess increased awareness of the importance of limiting its expansion. Furthermore, perceptions appear to transition from positive in childhood and youth to negative in adult life. We conclude that the current juncture is opportune for initiating Acacia control measures.

Biological invasions threaten biodiversity globally. In Australia, introduced and invasive European red foxes ( Vulpes vulpes ) are a major predator of native wildlife, and are implicated in numerous species extinctions, prompting large-scale fox population control programs. Lethal control—typically via poison (1080) baiting—is common, but the consistency of its efficacy has been questioned, and the desired outcomes are frequently not measured or evaluated. We aimed to assess the success and impacts of lethal fox control on fox activity, and subsequent effects on a co-occurring, invasive mesopredator (feral cat, Felis catus ), and native and invasive prey species. We surveyed three locations in the Wimmera region of Victoria, each experienced a different baiting regime (no baiting, standard systematic baiting, intensified baiting). Camera traps were deployed from April 2021 to August 2023 to determine predator activity alongside non-target herbivores. Baiting treatment was not associated with differences in fox or cat activity. Nurcoung (no baiting) had the lowest activity of both cats and foxes across the study. Fox activity patterns under standard baiting were higher than intensified baiting. Our results suggest that fox control might destabilise population dynamics of foxes, potentially facilitating increased activity levels through higher emigration rates from the surrounding agricultural environments. Our study highlights the critical importance of appropriately monitoring the outcomes of invasive species control programs to ensure the a priori strategic objectives are achieved. To achieve more effective fox population suppression broader, landscape-scale approaches that take a nil-tenure approach are essential.

Biotic resistance of pervasive native species to invasion may be an effective managing tool for exotic plants. The present study subjected the invasive aquatic plant in China, Alternanthera philoxeroides (Mart.) Griseb., the exotic species with high dispersal along the Yangtze River Basin of sub-tropical China, Myriophyllum aquaticum (Vell.) Verdc., and the pervasive native species in China, Ludwigia peploides subsp. stipulacea (Ohwi) Raven, to different treatment combinations of sediment type and flooding condition in a mesocosm experiment. Morphological traits, biomass allocation, and physiological traits were employed to evaluate the plant performance of the three species. We found that L. peploides performed faster stolon elongation and roots recruitment than the invasive species. A. philoxeroides had a higher leaf nitrogen concentration, lower values in leaf C/N ratio and leaf construction cost, and higher plasticity in leaf nitrogen concentration, however, a weaker space exploitation compared to L. peploides. Moreover, L. peploides might had higher photosynthetic efficiency than M. aquaticum due to the higher chlorophyll concentration and leaf nitrogen concentration. We speculate that L. peploides has the potential to resist the invasion and to be used as biocontrol species for the management of exotic invasive species since this pervasive native species has greater space exploitation.

Effective control measures for small-bodied invasive alien species (IAS) in lotic environments are essential for preserving native biodiversity and ecosystem health. This study integrates modeling and field-based removal data to assess the efficacy of electrofishing in controlling populations of the globally invasive Eastern mosquitofish Gambusia holbrooki across four lowland headwater streams in southern Greece over a one-year period. Results indicated significant reductions in mosquitofish post-removal abundance, although natural recruitment persisted, leading to population suppression rather than eradication. Indeed, our pre-removal population viability analysis suggested a temporary suppression of mosquitofish populations, influenced by factors such as the species’ life history and reproductive traits. Furthermore, our study suggests modifications of physical control methods expected to enhance effectiveness. Specifically, the narrow implementation timeframe of the removal actions highlights the need for multiple removal campaigns in consecutive years and for long-term population monitoring, thus aligning with past research. The timing of removal efforts is also critical as it must exploit seasonal variability in fish eradication susceptibility, by its implementation within the best “window of opportunity”. Finally, addressing knowledge gaps in the ecological impacts of IAS control methods as well as exploration of novel control and monitoring technologies, are also vital for informed management strategies. This study, by proposing modifications to fish removal planning and methodology, contributes to ongoing efforts for optimal IAS control, particularly in regions where such management approaches are underutilized.

Island florae are under threat from habitat loss and competition with introduced species worldwide. In the Galapagos Islands, the endemic tree daisy Scalesia pedunculata (Asteraceae) is the dominant tree in the cloud forest of Santa Cruz Island but suffers from competition with the invasive blackberry Rubus niveus. At the site Los Gemelos, a S. pedunculata population was monitored from 2014 to 2021 following mechanical and chemical removal of R. niveus from 17 plots and compared with 17 additional plots where R. niveus remained. The aim of this study was to evaluate the impacts of the R. niveus invasion on S. pedunculata by characterizing the effects of R. niveus removal. Parameters measured in S. pedunculata were diameter at breast height (DBH, from which annual growth rates were determined), total height, survival of individual plants, and recruitment. In the presence of R. niveus, S. pedunculata trees had smaller DBH stems and shorter asymptotic maximum heights, growth rates declined for thin trees, the mortality of larger trees was elevated, and S. pedunculata recruitment was absent. R. niveus removal resulted in DBH-ratios of S. pedunculata more frequently meeting our threshold for fast growth (1.2), trees growing significantly thicker and taller, annual mortality being lower (12.5% vs. 16.2% per year), and recruitment being successful. In the presence of R. niveus, lower survival, growth, and absent recruitment suggested that S. pedunculata could reach quasi-extinction in ~20 years. Swift and decisive management action is needed to prevent the Scalesia forest on Santa Cruz Island from disappearing in less than two decades.

Controlling invasive species is critical for conservation but can have unintended consequences for native species and divert resources away from other efforts. This dilemma occurs on a grand scale in the North American Great Lakes, where dams and culverts block tributary access to habitat of desirable fish species and are a lynchpin of long-standing efforts to limit ecological damage inflicted by the invasive, parasitic sea lamprey (Petromyzon marinusj. Habitat restoration and sea-lamprey control create conflicting goals for managing aging infrastructure. We used optimization to minimize opportunity costs ofhabitat gains for 37 desirable migratory fishes that arose from restricting sea lamprey access (0-25% increase) when selecting barriers for removal under a limited budget (US$1-105 million). Imposing limits on sea lamprey habitat reduced gains in tributary access for desirable species by 15-50% relative to an unconstrained scenario. Additional investment to offset the effect of limiting sea-lamprey access resulted in high opportunity costs for 30 of 37 species (e.g., an additional US$20-80 million for lake sturgeon [Acipenser fulvescens]) and often required ≥5% increase in sea-lamprey access to identify barrier-removal solutions adhering to the budget and limiting access. Narrowly distributed species exhibited the highest opportunity costs but benefited more at less cost when small increases in sea-lamprey access were allowed. Our results illustrate the value of optimization in limiting opportunity costs when balancing invasion control against restoration benefits for diverse desirable species. Such trade-off analyses are essential to the restoration of connectivity within fragmented rivers without unleashing invaders. El control de las especies invasoras es muy importante para la conservación pero puede tener consecuencias accidentales para las especies nativas y puede desviar los recursos lejos de otros esfuerzos. Este dilema ocurre a gran escala en los Grandes Lagos de América del Norte’ en donde las represas y las alcantarillas obstruyen el acceso tributario al hábitat de las especies deseables de peces y son un eje para los esfuerzos duraderos por limitar el daño ecológico causado por la especie invasora y parásita de lamprea marina (Petromyzon marinus). La restauración del hábitat y el control de la lamprea marina crean objetivos discrepantes para el manejo de la infraestructura en deterioro. Utilizamos la optimización para reducir los costos de oportunidad de las ganancias de hábitat de 37 peces migratorios deseables que surgieron de la restricción del acceso de la lamprea marina (incremento de 0-25%) cuando se seleccionaron barreras de extirpación bajo un presupuesto limitado (USD $1-105 millones). La imposición de límites sobre el hábitat de la lamprea redujo las ganancias del acceso tributario para las especies deseables en un 15-50% en relación a un escenario sin barreras. Las inversiones adicionales para compensar el efecto de la limitación del acceso de la lamprea marina resultaron en altas oportunidades de costo para 30 de las 37 especies (p.ej.: unos USD $20-80 millones para el esturión lacustre [Acipenser fulvescens]) y requirieron frecuentemente un incremento >5% en el acceso de lampreas marinas para identificar las soluciones de eliminación de barreras que se adhieren al presupuesto y limitan el acceso. Las especies con distribución restringida exhibieron los costos de oportunidad más altos pero beneficiaron más a un menor precio cuando se permitieron peaueños incrementos en el acceso a la lamprea marina. Nuestros resultados ilustran el valor de la optimización en la limitación de los costos de oportunidad cuando se balancea el control de invasión ante los beneficios de restauración para diversas especies deseables. Dichos análisis de compensaciones son esenciales para la restauración de la conectividad dentro de los ríos fragmentados sin liberar a los invasores.

The natural recolonization of native plant communities following invasive species management is notoriously challenging to predict, since outcomes can be contingent on a variety of factors including management decisions, abiotic factors, and landscape setting. The spatial scale at which the treatment is applied can also impact management outcomes, potentially influencing plant assembly processes and treatment success. Understanding the relative importance of each of these factors for plant community assembly can help managers prioritize patches where specific treatments are likely to be most successful. Here, using effects size analyses, we evaluate plant community responses following four invasive management treatments (1: fall glyphosate herbicide spray, 2: summer glyphosate herbicide spray, 3: summer imazapyr herbicide spray, 4: untreated control) applied at two patch scales (12,000 m and 1,000 m ) and monitored for 5 years. Using variation partitioning, we then evaluated the independent and shared influence of patch scale, treatment type, abiotic factors, and landscape factors on plant community outcomes following herbicide treatments. We found that reinvaded more quickly in large patches, particularly following summer herbicide treatments, while native plant cover and richness increased at a greater magnitude in small patches than large. Patch scale, in combination with abiotic and landscape factors, was the most important driver for most plant responses. Compared with the small plots, large patches commonly had deeper and more prolonged flooding, and were in areas with greater hydrologic disturbance in the landscape, factors associated with reduced native plant recruitment and greater cover. Small patches were associated with less flooding and landscape disturbance, and more native plants in the surrounding landscape than large patches, factors which promoted higher native plant conservation values and greater native plant cover and richness. Herbicide type and timing accounted for very little of the variation in native plant recovery, emphasizing the greater importance of patch selection for better management outcomes. To maximize the success of treatment programs, practitioners should first manage patches adjacent to native plant species and in areas with minimal hydrologic disturbance.

Control of invasive predators is a priority to protect island biodiversity. Understanding the responses of other species in multi-species invaded food webs is important to avoid unintended consequences. We use an intensive 2-year cat-trapping program in the vicinity of seabird colonies on Bruny Island, Tasmania, to investigate its effectiveness in reducing feral cat density and whether cat control influenced the behaviour and abundance of native and invasive mammal species. Cat density before control was extremely high around this seasonally rich food resource, much higher than on mainlands. Cat density was reduced 5.4-fold by control showing that trapping is effective in reducing cat density in this focussed landscape context. We found no direct effect of cat reduction on the abundance or behaviour of native or invasive mammalian prey species. Recruitment of invasive black rats and native swamp rats increased on the seabird colonies after the shearwater breeding season, and cats responded by increasing their presence on the colonies relative to surrounding areas. This suggests cascading bottom-up effects from a lagged productivity pulse provided by breeding seabirds which would require nutrient sampling to confirm. Our results highlight the complexity of subsequent effects of an invasive predator control on the broader ecosystem.

Natural resource managers use tools to control invasive species. In theory, stocking YY males or ZZ females would allow managers to skew sex ratios until populations collapse. In combination with other suppression methods, such as removal, this approach could be incorporated into Integrated Pest Management plans. For example, fishery managers have stocked YY males to control isolated non-native brook trout (Salvelinus fontinalis) populations. However, life histories and demographic factors (e.g., lifespans) vary across species and could affect the feasibility of skewing sex ratios as an effective control strategy for a given population. Likewise, some species may have sex determinations that do not allow population control through sex-skewing methods. We compared five representative aquatic invasive species with global invasion ranges for potential control by skewing the sex ratio through closed population simulations: red swamp crayfish (Procambarus clarkii), zebra mussels (Dreissena polymorpha), lake trout (Salvelinus namaycush), silver carp (Hypophthalmichthys molitrix), and Nile tilapia (Oreochromis niloticus). We determined that Nile tilapia, red swamp crayfish, and zebra mussels would be the most suitable to control through skewing the sex ratio assuming appropriate sex determination exists in the species. Lake trout could be eliminated by stocking YY males but would require either long stocking periods or high stocking numbers because of the long lifespan of the species. Silver carp populations were more difficult to crash because they live longer and produce many recruits. Broadly, these patterns demonstrated that short lived species lend themselves to control by skewing the sex ratio.

Culling can be an effective management tool for reducing populations of invasive species to levels that minimize ecological effects. However, culling is labour-intensive, costly, and may have unintended ecological consequences. In the Caribbean, culling is widely used to control invasive Indo-Pacific lionfish, Pterois volitans and P. miles , but the effectiveness of infrequent culling in terms of reducing lionfish abundance and halting native prey decline is unclear. In a 21-month-long field experiment on natural reefs, we found that culling effectiveness changed after the passage of a hurricane part-way through the experiment. Before the hurricane, infrequent culling resulted in substantial reductions in lionfish density (60–79%, on average, albeit with large uncertainty) and slight increases in native prey species richness, but was insufficient to stem the decline in native prey biomass. Culling every 3 months (i.e., quarterly) and every 6 months (i.e., biannually) had similar effects on lionfish density and native prey fishes because of high rates of lionfish colonization among reefs. After the hurricane, lionfish densities were greater on all culled reefs compared to non-culled reefs, and prey biomass declined by 92%, and species richness by 71%, on biannually culled reefs. The two culling frequencies we examined therefore seem to offer a poor trade-off between the demonstrated conservation gains that can be achieved with frequent culling and the economy of time and money realized by infrequent culling. Moreover, stochastic events such as hurricanes can drastically limit the effectiveness of culling efforts.