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A large and increasing number of ecosystems of the planet are now invaded by alien species, resulting in detrimental impacts on biodiversity, human health, and ecosystem services (IPBES 2019). Many of these impacts can be defined and quantified as economic costs; expenditures to prevent, reduce or mitigate the losses caused by invasive alien species (IAS). Reports on the global economic costs over the last 50 years estimate that IAS are responsible for a minimum of US$1.288 trillion (2017 US dollars) in damages, a number that is steadily rising over time (Diagne et al. 2021a). Understanding and estimating economic damages caused by IAS is particularly important given that new introductions of alien species and impacts are increasing globally with no sign of slowing down (Seebens et al. 2017; Essl et al. 2020). In addition, just as current and future projections of numbers and types of IAS vary across ecosystems (van Kleunen et al. 2015; Essl et al. 2020), impacts and costs of biological invasions differ widely across space and time (Angulo et al. 2021b; Diagne et al. 2021a). Improving economic cost estimates of biological invasions across regions helps scientists, managers, and stakeholders to develop and inform benefit-cost analyses and policies for dealing with invasive alien species. Previous studies have modelled and estimated the economic costs of biological invasions for specific countries (e.g., Pimentel et al. 2005; Hoffmann and Broadhurst 2016) or globally (e.g., Diagne et al. 2021a), but a standardized assessment of costs of biological invasions with detailed information for countries and regions was lacking for most regions of the world. In this special issue on the “The Economic costs of biological invasions in the world,” 63 authors address this issue by bringing together 19 papers from 13 countries and 6 supra-national regions that report on the economic cost-dimension of biological invasions (Fig. 1, Table 1). Collectively, they provide a global, innovative perspective detailing the economic costs of biological invasions while also providing regional information to help raise public awareness, and support efficient and cost-effective decision-making Financial support to EGB was provided by the Spanish Ministry of Science (projects RED2018‐102571‐T, and PID2019-103936GB-C21) and the Government of Catalonia (ref. 2017 SGR 548)

Invasive alien species pose a serious threat to the integrity and function of natural ecosystems. Understanding how these invaders alter natural communities is therefore an important aspect in predicting the likely future outcomes of biological invasions. Many studies have documented the consequences of invasive alien species on native community structure, through the displacement and local extinction of native species. However, sampling methods and intensities are rarely standardised across such studies, meaning that it is not clear whether differences in response among native communities to the same invader species are due to biological differences between the invaded regions, or differences in the methodologies used. Here we use a matched sampling methodology to compare the effects of the Argentine ant (Linepithema humile Mayr) on native ant community assemblages in two distinct biogeographical regions that share similar ecologies: Girona (Spain) and Jonkershoek Nature Reserve (South Africa). We found a strong negative association between L. humile presence and native ant species richness within both geographic regions. However, the effects differed between the two study regions: in Girona, a single native ant species (Plagiolepis pygmaea) persisted in invaded sites; by contrast, substantially more native ant species persisted at invaded sites in Jonkershoek Nature Reserve. In addition, in Jonkershoek Nature Reserve, the abundance of certain native species appeared to increase in the presence of L. humile. This study therefore demonstrates the potential variable effects of an invasive species in contrasting locations within different biogeographical regions. Future work should explore the causes of this differential resistance among communities and expand standardised sampling approaches to more invaded zones to further explore how local biotic or abiotic conditions of a region determine the nature and extent of impact of L. humile invasion on native ant communities This work was funded by grants and awards from the Natural Environmental Research Council (NERC) Case Studentship awarded to SS, JB and RN (NE/K007076/1); COST Action TD1209 (ECOST-STSM-TD1209: 070915-062123, 010715-062122, and 160614-046307); and Varley-Gradwell Travelling Fellowship

Two of the world’s most invasive ants, Linepithema humile and Lasius neglectus, are destined to overlap in range as they continue to spread throughout Europe. Although L. humile arrived first, and is therefore more numerically abundant, L. neglectus is the more behaviorally dominant of the two. We performed lab trials to determine whether L. humile could use numerical abundance to overcome the behavioral dominance of L. neglectus and whether the ants’ behavioral patterns shifted when the species co-occurred. We found that L. neglectus was more aggressive when less abundant, whereas the opposite was true of L. humile. When L. neglectus was outnumbered, it employed aggressive behaviors, such as biting or chemical attacks, more frequently than L. humile; it also utilized a behavioral sequence that included mandible opening and biting. Our results for these species support the hypothesis that species modulate their behavior towards competitors, which facilitates the understanding of how multiple invasive ant species can co-occur in a given area. Moreover, our study shows that the co-occurrence of invasive species could result from the use of two strategies: (1) the Bourgeois strategy, in which aggressiveness changes based on numerical dominance and (2) the dear-enemy strategy, in which aggressiveness is reduced when competitors co-occur. Since these strategies may lead to territory partitioning, we suggest that the behavioral flexibility displayed by both species when they overlap may allow local co-occurrence and increase their likelihood of co-occurrence during their range expansion in Europe, which could have a negative cumulative impact on invaded areas.

Scientific and grey literature on invasive alien species (IAS) is conditioned by social, economic and political priorities, editorial preferences and species and ecosystem characteristics. This leads to knowledge gaps and mismatches between scientific research interests and management needs. We reviewed the literature on IAS management in Spain found in Scopus, Web of Science, Google Scholar and Dialnet to identify key deficiencies and priority research areas. The collected literature was classified, employing features describing formal aspects and content. We used bibliometric and keyword co-occurrence network analyses to assess the relationship between features and reveal the existence of additional topics. Most of the compiled documents (n = 388) were focused on terrestrial ecosystems and inland waters, whereas marine and urban ecosystems were under-represented. The literature was largely generic and not species-specific, focusing on raising awareness and proposing changes on current regulation as prominent approaches to prevent further introductions. The compiled authors exhibited many clear publishing preferences (e.g. language or document type), but less regarding target taxa. In addition, there was a strong association between species and the different features considered, especially between the methodological approach (e.g. review, field experiment) and the primary emphasis of study (i.e. basic/theoretical, applied or interdisciplinary). This indicates that research on IAS has had a strong species-specific focus. References about terrestrial species focused mainly on vascular plants, whereas references about inland waters were mostly on fishes and the giant reed (Arundo donax), which has been managed with partial success. Animal culling and plant removal were the most frequent eradication and small-scale control treatments, whereas the documents addressing wider spatial scales were largely theoretical. Consequently, the success of described treatments was largely uncertain. Spanish invasion science research has been occasionally innovative, incorporating novel technologies (e.g. species distribution modelling) and engaging society with citizen-science approaches. However, the ratio between basic/theoretical and applied studies indicates that more applied research/management is needed, especially in inland waters and marine ecosystems. We call for increasing effort in the effective dissemination of experience in IAS management to enhance current practical knowledge, including that of schemes undertaken by public agencies. © 2021. Rafael Muñoz-Mas et al.. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited., Spanish Ministry of Science and Innovation RED2018‐102571‐T, Spanish State Research Agency, Spanish State Research Agency, European Regional Development Fund PID2020- 118550RB, PID2019-103936GB-C21, RTI2018-093504-B-I00, Government of Catalonia 2017 SGR 548, Spanish Ministry of Science and Innovation FJCI2016-30829

Scenario analysis has emerged as a key tool to analyze complex and uncertain future socio-ecological developments. However, currently existing global scenarios (narratives of how the world may develop) have neglected biological invasions, a major threat to biodiversity and the economy. Here, we use a novel participatory process to develop a diverse set of global biological invasion scenarios spanning a wide range of plausible global futures through to 2050. We adapted the widely used “two axes” scenario analysis approach to develop four families of four scenarios each, resulting in 16 scenarios that were later clustered into four contrasting sets of futures. Our analysis highlights that socioeconomic developments and technological innovation have the potential to shape biological invasions, in addition to well-known drivers, such as climate and human land use change and global trade. Our scenarios partially align with the shared socioeconomic pathways created by the climate change research community. Several factors that drive differences in biological invasions were underrepresented in the shared socioeconomic pathways; in particular, the implementation of biosecurity policies. We argue that including factors related to public environmental awareness and technological and trade development in global scenarios and models is essential to adequately consider biological invasions in global environmental assessments and thereby obtain a more integrative picture of future social–ecological developments This research was funded through the COST Action “Alien Challenge” [Grant number TD1209]; the 2017–2018 Belmont Forum and BiodivERsA joint call for research proposals, under the BiodivScen ERA-Net COFUND programme, and with the funding organisations AEI, FWF and BMBF [grant numbers AEI PCI2018-092966 (NRP)/FWF project 4011-B32 (FE, SD, GL, BeL)/BMBF projects 01LC1807A (HS) and 01LC1807B (JMJ)]; Deutsche Forschungsgemeinschaft [grant numbers InDyNet, JE 288/8-1; JE 288/9-1, 9-2 (JMJ)/via iDiv FZT 118, 202548816 (MW)]; OP RDE grant EVA4.0 [grant number CZ.02.1.01/0.0/0.0/16_019/0000803] (AML); CONICYT [grant number AFB170008] (AP); UK-SCAPE programme, Natural Environment Research Council [grant number NE/R016429/1] (HER)

We report new localities for Callinectes sapidus in the Iberian Peninsula that widen the north-eastern limit of its distribution by more than 206 km along the Iberian Mediterranean coastline. This invasive species has been captured in the estuaries of the Fluvià, Muga and Ter rivers and has become established in the Fluvià River in only nine months since the first individual was detected. These reports show how rapid expansion of C. sapidus can be and that this may be preceded by the presence of isolated individuals We gratefully acknowledge the scientific team of the European Life project “Pletera” (LIFE13 NAT/ES/001001) and the Sorelló S.L. company for sharing their field results. This project has been financially supported by Natura Montfred company and the Aiguamolls de l’Empordà Natural Park (PNAE)

Invasive alien species are one of the main components of global ecological change, the second known cause of animal extinctions, and very costly in terms of ecosystem services. Invasive alien species and damming are two of the most impacting alterations in freshwater ecosystems, and understanding the processes that govern biological invasions in these habitats is of enormous conceptual and practical importance. About 39 competing and overlapping hypotheses have been proposed in invasion biology that have been recently grouped in four (or five) concept clusters, namely the: propagule, resource availability, biotic interaction and Darwin’s clusters. We analyzed the relative importance of three of these concept clusters in Neotropical fish assemblages, using data from 29 reservoirs and variation partitioning analyses. We show that alien fish assemblages respond to variation in limnological characteristics in a way similar than native species, usually with positive effects of increased temperature, conductivity and chlorophyll-a concentration and decreasing turbidity. Overall, we found support for some hypotheses included in resource availability and Darwin’s clusters, such as increased resource availability and biotic acceptance, and no evidence of strong biotic resistance, marked effects of human disturbance, as measured by land-use changes, or propagule/colonization pressures. We discuss the potential reasons and management implications of these findings. Our study illustrates that analyzing the importance of classical hypotheses of invasion biology in tropical freshwaters and other ecosystems enhances ecological understanding and provides practical implications to prioritize management interventions and mitigate ecological impacts We express our appreciation to the PRONEX-MCT/CNPq for financial support and to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil, process number 88882.344464/2019-01) and to Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Brazil, process number 165319/2017-8) for the fellowships to graduate students. AAA received scientific productivity fellowships from CNPq. We are also grateful for the funding provided by CAPES through “Programa de Doutorado-sanduíche no Exterior” (PDSE, processes number 88881.361907/2019-01 and 88881.361938/2019-01) that allowed a research stay of CMM and MMG at the University of Girona. Additional financial support was provided by the Spanish Ministry of Science and Innovation (projects RED2018‐102571‐T and PID2019-103936GB-C21) and the Government of Catalonia (ref. 2017 SGR 548)

Invasive species pose a major threat to global diversity, and once they are well established their eradication typically becomes unfeasible. However, certain natural mechanisms can increase the resistance of native communities to invaders and can be used to guide effective management policies. Both competition and herbivory have been identified as potential biotic resistance mechanisms that can limit plant invasiveness, but it is still under debate to what extent they might be effective against well-established invaders. Surprisingly, whereas biotic mechanisms are known to interact strongly, most studies to date have examined single biotic mechanisms separately, which likely influences our understanding of the strength and effectiveness of biotic resistance against invaders. Here we use long-term field data, benthic assemblage sampling, and exclusion experiments to assess the effect of native assemblage complexity and herbivory on the invasion dynamics of a successful invasive species, the alga Caulerpa cylindracea. A higher complexity of the native algal assemblage limited C. cylindracea invasion, probably through competition by canopy-forming and erect algae. Additionally, high herbivory pressure by the fish Sarpa salpa reduced C. cylindracea abundance by more than four times. However, long-term data of the invasion reflects that biotic resistance strength can vary across the invasion process and it is only where high assemblage complexity is concomitant with high herbivory pressure, that the most significant limitation is observed (synergistic effect). Overall, the findings reported in this study highlight that neglecting the interactions between biotic mechanisms during invasive processes and restricting the studied time scales may lead to underestimations of the true capacity of native assemblages to develop resistance to invaders., Funding for this project was obtained from the Spanish Ministry Project ANIMA (CGL2016-76341-R, MINECO/FEDER, UE), the European Union’s EMFS Program, AFRIMED (EASME/EMFF/2017/1.2.1.12/S4/01/SI2.789059), the Spanish Autonomous Organism of National Parks through the project BIGPARK (project 2017-2462), and the Padi Foundation to FT (CGA App: 5134). JS received the support of a fellowship from “La Caixa” Foundation (ID 100010434) with code (LCF/BQ/DE17/11600001).

The extreme body sizes of megafishes associated with their high commercial values and recreational interests have made them highly threatened in their native range worldwide by human-induced impacts such as overexploitation. Meanwhile, some megafishes have been introduced outside of their native range. A notable example is the European catfish (Silurus glanis), one of the few siluriforms native to Eastern Europe. It is among the 20 largest freshwater fish worldwide, attaining a total length over 2.7 m and a documented mass of 130 kg. Its distinct phylogeny and extreme size imply many features that are rare among other European fish, including novel behaviours (massive aggregations, beaching), consumption of large bodied prey, fast growth rates, long lifespan, high fecundity, nest guarding and large egg sizes. The spread of the species is likely to continue due to illegal introductions, primarily for recreational angling, coupled with natural range extension associated with climate change. Here, the most recent knowledge on the current distribution and the ecology of the species are reviewed. A series of key research questions are identified that should stimulate new rese arch on this intriguing, yet largely unknown, species and, more generally, on the ecology of freshwater invaders This work was produced as part of the ‘‘European Catfish Working Group’’ that was financially supported by the University of Toulouse. Individual members of the group were supported by the Spanish Ministry of Economy and Competitiveness (Project CGL2013-43822-R), the Government of Catalonia (ref. 2014 SGR 484), the European Commission (COST Action TD1209), Czech Science Foundation (Project 16-06498S) and the French Laboratory of Excellence Project ‘‘TULIP’’ (ANR-10-LABX-41; ANR-11-IDEX-0002-02)

Identificación y validación de PNU en dos especies invasoras: el mejillón cebra (Dreissena polymorpha) y la almeja asiática (Corbicula fluminea) El desarrollo de las plataformas asequibles de secuenciación masiva en paralelo (SMP) ha reducido el coste y el tiempo en la identificación de marcadores de polimorfismos de nucleótido único (PNU) para su uso en estudios de genética de poblaciones y de conservación. Tras la SMP, suele ser necesaria una segunda validación. El análisis de las curvas de fusión a alta resolución (HRMA en su sigla en inglés) es un método rápido y sencillo para escanear mutaciones y, por tanto, es un protocolo adecuado de validación de dichos marcadores, especialmente en especies no modelo. En este trabajo se presenta un juego de nueve marcadores polimórficos de PNU nuevos identificados mediante SMP y validados con el HRMA en dos especies invasoras (el mejillón cebra Dreissena polymorpha y la almeja asiática Corbicula fluminea), que pueden utilizarse en estudios de genética de poblaciones para evaluar y entender correctamente los episodios de invasión pasados y los que podrían ocurrir en el futuro., The development of affordable massive parallel sequencing (MPS) has reduced both time and costs of SNP identification for use in conservation and population genetic studies. After MPS, a second validation is usually required. High resolution melting analysis (HRMA) is a fast and simple method for mutation scanning, and thus a suitable validation protocol, particularly in non–model species. We present a set of nine novel polymorphic SNPs identified by MPS and validated with HRMA in two invasive species (the zebra mussel Dreissena polymorpha and the Asian clam Corbicula fluminea). These SNPs can be used in genetic studies to accurately assess and understand past and future invasion events.

Este artículo contiene 8 páginas, 2 figuras, 1 tabla., Managing invasive alien species is particularly challenging in the ocean mainly because marine ecosystems are highly connected across broad spatial scales. Eradication of marine invasive species has only been achieved when species were detected early, and management responded rapidly. Generalized approaches, transferable across marine regions, for prioritizing actions to control invasive populations are currently lacking. Here, expert knowledge was elicited to prioritize 11 management actions for controlling 12 model species, distinguished by differences in dispersion capacity, distribution in the area to be managed, and taxonomic identity. Each action was assessed using five criteria (effectiveness, feasibility, acceptability, impacts on native communities, and cost), which were combined in an ‘applicability’ metric. Raising public awareness and encouraging the commercial use of invasive species were highly prioritized, whereas biological control actions were considered the least applicable. Our findings can guide rapid decision-making on prioritizing management options for the control of invasive species especially at early stages of invasion, when reducing managers' response time is critical., This work is a contribution of the ANR project “PAVIS: Assessing the relationships between marine protected areas and invasive species” (ANR-16-ACHN-0016-01) and the COST Action 15121 “MarCons: Advancingmarine conservation in the European and contiguous seas” supported by the European Cooperation in Science and Technology (CA15121).

Standardized tools are needed to identify and prioritize the most harmful non-native species (NNS). A plethora of assessment protocols have been developed to evaluate the current and potential impacts of non-native species, but consistency among them has received limited attention. To estimate the consistency across impact assessment protocols, 89 specialists in biological invasions used 11 protocols to screen 57 NNS (2614 assessments). We tested if the consistency in the impact scoring across assessors, quantified as the coefficient of variation (CV), was dependent on the characteristics of the protocol, the taxonomic group and the expertise of the assessor. Mean CV across assessors was 40%, with a maximum of 223%. CV was lower for protocols with a low number of score levels, which demanded high levels of expertise, and when the assessors had greater expertise on the assessed species. The similarity among protocols with respect to the final scores was higher when the protocols considered the same impact types. We conclude that all protocols led to considerable inconsistency among assessors. In order to improve consistency, we highlight the importance of selecting assessors with high expertise, providing clear guidelines and adequate training but also deriving final decisions collaboratively by consensus

The introduction of species is one of the five principle causes of the loss of biodiversity and, in the recent past, is a problem which has gathered force. This increase is a consequence of new global forces, such as transport and commerce, are ending a long period of biological isolation. This present study is centred on the amphibians and has, as its objective, to evaluate and to recognise the burden of traffic in fauna on the arrival of new species on a geographic area in which they are not native forms. In order to carry out this project, bibliographical research was carried out in order to understand the problem and to identify the sources which would best serve for the basis of data in a second part. The data base is the foundation of the study as it permits knowledge of: the species of amphibians which have arrived in Spain from Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), those which are protected by the said convention, the species which are found to be commercially available in the internal market in the country and the invasive exotic amphibians which are present in the environment. This generated data was treated to discover the results and confirm or refute the initial predictions, which are the following; (1) the number of transactions regulated by CITES has increased over the past years, (2) there should be no species protected by the Convention being commercially available in Spain and, (3) the commercialization of exotic amphibians has a negative impact not only on the native ecosystem but also on the receiving ecosystem. With the obtained results, the first and third predictions have been confirmed, while the second has been refuted. In this way a significant increase in the number of transactions regulated by CITES has been observed, but only for anura, not for the urodela and the caecilians. On the other hand, based on the numbers of examples commercially available, negative consequences can be inferred from the traffic in fauna for native and receptor ecosystems. Furthermore, protected species were not expected to be found in the businesses studied, but various examples were found in the research carried out. With the study carried out it was hoped to recognise the importance and the consequences of commerce in the affected species, over the originating ecosystems and, often, on the receptor ecosystems in which they can become naturalised

Ecologists have recently devoted their attention to the study of species traits and their role in the establishment and spread of nonindigenous species (NIS). However, research efforts have mostly focused on studies of terrestrial taxa, with lesser attention being dedicated to aquatic species. Aquatic habitats comprise of interconnected waterways, as well as exclusive introduction vectors that allow unparalleled artificial transport of species and their propagules. Consequently, species traits that commonly facilitate biological invasions in terrestrial systems may not be as represented in aquatic environments. We provide a global meta-analysis of studies conducted in both marine and freshwater habitats. We selected studies that conducted experiments with native and NIS under common environmental conditions to allow detailed comparisons among species traits. In addition, we explored whether different factors such as species relatedness, functional feeding groups, latitude, climate, and experimental conditions could be linked to predictive traits. Our results show that species with traits that enhance consumption and growth have a substantially increased probability of establishing and spreading when entering novel ecosystems. Moreover, traits associated with predatory avoidance were more prevalent in NIS and therefore favour invasive species in aquatic habitats. When we analysed NIS interacting with taxonomically distinctive native taxa, we found that consumption and growth were particularly important traits. This suggests that particular attention should be paid to newly introduced species for which there are no close relatives in the local biota. Finally, we found a bias towards studies conducted in temperate regions, and thus, more studies in other climatic regions are needed. We conclude that studies aiming at predicting future range shifts should consider trophic traits of aquatic NIS as these traits are indicative of multiple interacting mechanisms involved in promoting species invasions This research was supported by the Spanish Ministry of Economy and Competitiveness (projects CGL2013-43822-R and CGL2015-69311-REDT), the Government of Catalonia (ref. 2014 SGR 484), and the European Commission (COST Action TD1209). P.S. work was supported by a doctoral fellowship from the European Commission (Erasmus Mundus Partnership ‘Techno’, 204323-1-2011-1-FREMA21)

In freshwater ecosystems, abiotic factors such as flow regime and water quality are considered important predictors of ecosystem invasibility. The aim of this study was to investigate the critical swimming capacity and metabolism of the eastern mosquitofish, Gambusia holbrooki, focusing on sex and size effects, to evaluate the influence of water flow on its invasive success. Specimens of mosquitofish were captured from the Ter Vell lagoon (L'Estartit, north-eastern Spain) in July 2014, and we measured the critical swimming speed (Ucrit) and oxygen consumption of individual fish (30 females and 30 males) using a mini swim tunnel. The mean Ucrit of this poeciliid fish was estimated at 14.11 cm·s-1 (range = 4.85-22.26), which is lower than that of many other fishes of similar size and confirms that this species is limnophilic and its invasive success might be partially explained by hydrologic alterations. However, the Ucrit and maximal metabolic rate vary markedly with fish size and sex, with males having much higher values for the same body mass, and thus probably being more resistant to strong water flows. Multiple regression models illustrate that multivariate analyses might increase the predictive power and understanding of swimming performance and metabolic traits, compared to results from conventional simple regressions This research was supported by the Spanish Ministry of Economy and Competitiveness (project CGL2013-43822-R), the Government of Catalonia (ref. 2014 SGR 484), the European Commission (COST Action TD1209) and the Brazilian Ministry of Education (CAPES, ref. 88881.068352/2014-01). P.S. and Y.L. benefitted from fellowships from the European Commission (Erasmus Mundus Partnership ‘Techno’, 204323-1-2011-1-FR-EMA21)

Seed dispersal is a fundamental process in the lifecycle of all flowering plants. Many plant species have evolved specialist associations with biotic vectors to facilitate dispersal. Such specialised interactions mean that these associations are potentially highly sensitive to disruption, e.g. from invasive species. However, despite this threat we still understand remarkably little about how such perturbations affect the dynamics and efficiency of the seed-dispersal process. In this study we quantify the impacts of an invasive ant across three key phases of the seed dispersal process: seed removal, distribution and placement, in order to determine the stages of seed dispersal most vulnerable to disruption by invaders. Using the Argentine ant (Linepithema humile) as a model, we show that invaded sites exhibited a significant decrease in seed dispersal services across all three phases of the dispersal process, relative to non-invaded sites. Seeds dispersed in invaded sites were: (a) less likely to be transported; (b) potentially distributed over a smaller spatial area, and (c) less likely to be placed at soil depths favourable for germination and establishment compared to those dispersed in non-invaded sites. These results reveal that ant-mediated seed dispersal services are significantly reduced by an invasive species at multiple stages in the dispersal process. Reductions in the efficacy of seed dispersal, combined with shifts in the ecological and geographical patterns of dispersal, may lead to cascading impacts on plant species composition and community structure. This study shows how an invasive ant can affect seed dispersal at several stages in the dispersal process This work was funded by grants from the COST Action TD1209 (ECOSTSTSM-TD1209: 070915-062123, 010715-062122, and 160614-046307) and a National Environmental Research Council Case Studentship awarded to SS, JB and RN (NE/K007076/1)

Eastern Mosquitofish (Gambusia holbrooki) is an invasive and globally widespread species that is considered highly tolerant. We used species distribution models (SDMs) to assess factors, including the role of anthropogenic perturbation, that mediate its invasion on a regional scale. A better understanding of the important large-scale factors may help us identify future areas of concern and potential avenues for control. We built SDMs from presence records and randomly selected pseudo-absences of mosquitofish on a 10- × 10-km grid. We used 10 modeling techniques implemented in the biomod2 software and ensemble forecasts. Final models contained 12 environmental predictors, including natural environmental factors (elevation, slope, topographic index, precipitation, accumulated flow, temperature mean and range) and anthropogenic perturbation indicators (population density, urban and agricultural land uses, number of local and upstream dams). Elevation, temperature, and accumulated flow most strongly influenced mosquitofish distribution, and mosquitofish were found more frequently in downstream, warmer waters. Anthropogenic features, except the number of upstream dams, were poorer predictors of mosquitofish presence than were natural environmental factors. The best models suggested that mosquitofish are more likely to occur in areas with more dams upstream, but removing this predictor did not strongly affect model results. Restoration efforts or modifications to anthropogenic features appear unlikely to alter mosquitofish distribution patterns, highlighting the importance of preventing introductions to new areas. Mosquitofish have been extensively documented in the Iberian Peninsula, but consensus methods suggest many additional suitable areas from which records were not found. Thus, this highly invasive species is or may become much more widely distributed than current observations in the region Financial support was provided by the Spanish Ministry of Economy and Competitiveness (projects CGL2009-12877-C02-01, CSD2009-00065, and CGL2013-43822-R), the University of Girona (project SING12/09), and the Government of Catalonia (ref. 2014 SGR 484)

Animal behaviour is of fundamental importance but is often overlooked in biological invasion research. A problem with such studies is that they may add pressure to already threatened species and subject vulnerable individuals to increased risk. One solution is to obtain the maximum possible information from the generated data using a variety of statistical techniques, instead of solely using simple versions of linear regression or generalized linear models as is customary. Here, we exemplify and compare the use of modern regression techniques which have very different conceptual backgrounds and aims (negative binomial models, zero-inflated regression, and expectile regression), and which have rarely been applied to behavioural data in biological invasion studies. We show that our data display overdispersion, which is frequent in ecological and behavioural data, and that conventional statistical methods such as Poisson generalized linear models are inadequate in this case. Expectile regression is similar to quantile regression and allows the estimation of functional relationships between variables for all portions of a probability distribution and is thus well suited for modelling boundaries in polygonal relationships or cases with heterogeneous variances which are frequent in behavioural data. We applied various statistical techniques to aggression in invasive mosquitofish, Gambusia holbrooki, and the concomitant vulnerability of native toothcarp, Aphanius iberus, in relation to individual size and sex. We found that medium sized male G. holbrooki carry out the majority of aggressive acts and that smaller and medium size A. iberus are most vulnerable. Of the regression techniques used, only negative binomial models and zero-inflated and expectile Poisson regressions revealed these relationships This research was supported by a Marie Curie International Reintegration Grant within the 7th European Community Framework Programme (KM). Additional support was provided by the Spanish Ministry of Economy and Competitiveness (project CGL2013-43822-R), the University of Girona (project SING12/09), the Government of Catalonia (ref. 2014 SGR 484), and the European Commission (COST Action TD1209)

Polydomy associated with unicoloniality is a common trait of invasive species. In the invasive Argentine ant, colonies are seasonally polydomous. Most follow a seasonal fission-fussion pattern: they disperse in the spring and summer and aggregate in the fall and winter. However, a small proportion of colonies do not migrate; instead, they inhabit permanent nesting sites. These colonies are large and highly polydomous. The aim of this study was to (1) search for differences in the fecundity of queens between mother colonies (large and permanent) and satellite colonies (small and temporal), (2) determine if queens in mother and satellite colonies have different diets to clarify if colony size influences social organization and queen feeding, and (3) examine if colony location relative to the invasion front results in differences in the queen's diet. Our results indicate that queens from mother nests are more fertile than queens from satellite nests and that colony location does not affect queen oviposition rate. Ovarian dissections suggest that differences in ovarian morphology are not responsible for the higher queen oviposition rate in mother vs. satellite nests, since there were no differences in the number and length of ovarioles in queens from the two types of colonies. In contrast, the higher δ15N values of queens from mother nests imply that greater carnivorous source intake accounts for the higher oviposition rates This work was supported by the Ministry of Science and Innovation of the Government of Spain, and EU ERDF funds (CGL2010-16451)

The aquarium trade has been identified as an important vector of aquatic invasive species but this question has mostly been investigated in North America. We investigated the variation in diversity and species composition in different trade types in southwestern Europe (three major international wholesalers, different retail store types, and local internet forums), mostly in Spain and Portugal. As in previous studies, the diversity of fishes in the aquarium trade was vast, with a total of 20 orders, 79 families, and 1,133 fish species detected in the trade types analyzed. 248 species were observed in a single metropolitan area (Barcelona), with estimates of about 294 species being present. International wholesalers had higher species richness and evenness, with a single one having over 700 species. General pet stores had much lower evenness but due to high turnover had a total richness of over 200 species. Internet forums had the lowest evenness but similar richness. The different commerce types varied significantly in relative species abundance with about a dozen of popular fish species (e.g., goldfish, Siamese fighting fish, common carp, guppy, swordtails) dominating the retail stores, particularly the general pet stores. Our results imply that frequency in the trade varies strongly among species and commerce types and although general pet stores have usually low diversity, this is compensated with a higher species turnover. Many of the most popular species are well known invasive species and some of the species available are temperate species that might establish in Europe, reinforcing the need for more careful implementation of education programs, regulation and monitoring of trade, and internalization of environmental costs by the industry We thank the aquarium websites mentioned in the methods for the valuable information provided, the Spanish Ministry of Science for financial support (CGL2009-12877-C02-01 and Consolider-Ingenio 2010 CSD2009-00065), and Julian D. Olden, the associate editor, and anonymous reviewers for insightful comments on the manuscript

Because insectivorous birds must evaluate resources for reproduction before settling into a breed- ing habitat, they can fall into an ecological trap if informative cues about habitat suitability become dissociated from their actual yield. Given their potential to affect ecological networks, invasive ant species are potential candidates for triggering such ecological traps. We combined observational and experimental approaches to examine whether the variation in food supply for nestlings resulting from the invasion of the Argentine ant, Linepithema humile, had any influence on the breeding ecology of the blue tit, Cyanistes caeruleus, an insectivorous foliage-gleaner. We inves- tigated the effects of the ant invasion on breeding performance (nesting success, clutch size, brood size and breeding success) and offspring quality (body size and condition, developmental stability and plumage colour) in replicated Mediterranean forest areas over a period of 3 years. There was no evidence that the reduction in caterpillar availability resulting from the invasion had a concurrent negative effect on the blue tit’s ability to successfully rear nestlings in optimal conditions, at least as measured here. Although the raw figures suggest an increased level of nutritional stress in blue tits breeding in invaded forests, the data analyses showed no significant alterations in terms of productiv- ity or offspring fitness. The reproductive performance of the blue tit has been shown to be remarkably resilient to the Argentine ant-mediated food shortage, either because the prey reduction following the invasion did not reach a critical threshold or because of compensa- tory activity by the progenitors. We cannot conclusively reject an ecological trap triggered by the ant invasion on blue tits, since neither fledgling recruitment nor the prospective survival of parents were assessed. Even though we could not confirm short-term consequences of the Argentine ant invasion on blue tit reproductive fitness, the long-term bottom-up effects of the invasion remain unknown and should not be ruled out

The zebra mussel (Dreissena polymorpha Pallas, 1771) and the quagga mussel (D. rostriformis Deshayes, 1838) are successful invasive bivalves with substantial ecological and economic impacts in freshwater systems once they become established. Since their eradication is extremely difficult, their detection at an early stage is crucial to prevent spread. In this study, we optimized and validated a qPCR detection method based on the histone H2B gene to quantify combined infestation levels of zebra and quagga mussels in environmental DNA samples. Our results show specific dreissenid DNA present in filtered water samples for which microscopic diagnostic identification for larvae failed. Monitoring a large number of locations for invasive dreissenid species based on a highly specific environmental DNA qPCR assay may prove to be an essential tool for management and control plans focused on prevention of establishment of dreissenid mussels in new locations We are indebted to different colleagues for zebra mussel sample collections: Concha Durán (Ebro Hydrografic Confederation, Spain) for the logistic advice; Anna Terrats and Carolina Solà (Catalan Water Agency from the Government of Catalonia, Spain) for the filtered-water environmental samples. We would thank to Mariona Palacios for her collaboration in the analysis into her Final Master Project. This research was carried out within the objectives of the research project CGL200909407 of the Spanish Ministerio de Ciencia e Innovación (MICINN)

Because invasive species threaten the integrity of natural ecosystems, a major goal in ecology is to develop predictive models to determine which species may become widespread and where they may invade. Indeed, considerable progress has been made in understanding the factors that influence the local pattern of spread for specific invaders and the factors that are correlated with the number of introduced species that have become established in a given region. However, few studies have examined the relative importance of multiple drivers of invasion success for widespread species at global scales. Here, we use a dataset of >5,000 presence/absence records to examine the interplay between climatic suitability, biotic resistance by native taxa, human-aided dispersal, and human modification of habitats, in shaping the distribution of one of the world's most notorious invasive species, the Argentine ant (Linepithema humile). Climatic suitability and the extent of human modification of habitats are primarily responsible for the distribution of this global invader. However, we also found some evidence for biotic resistance by native communities. Somewhat surprisingly, and despite the often cited importance of propagule pressure as a crucial driver of invasions, metrics of the magnitude of international traded commodities among countries were not related to global distribution patterns. Together, our analyses on the global-scale distribution of this invasive species provide strong evidence for the interplay of biotic and abiotic determinants of spread and also highlight the challenges of limiting the spread and subsequent impact of highly invasive species We acknowledge financial support from the Centre of Excellence for Invasion Biology (N.R.-P. and D.M.R.), from the Catalan Agency for Management of University and Research Grants (Generalitat de Catalunya) through Beatriu de Pinós Postdoctoral Grants 2006 BP-A 10124 and 2008 BP-B 00042 (to N.R.-P.), from the Hans Sigrist Foundation (to D.M.R.), from the Spanish Ministry of Science and Innovation Grant CGL2007-64080-C02-02/BOS (to C.G. and N.R.-P.), from the Spanish Ministry of Science and Innovation and the European Regional Development Fund Grant CGL2007-64080-C02-01/BOS (to X.E.), from the Blue Skies Programme of the National Research Foundation (to C.H.), from the Danish National Research Foundation (to J.S.P.), from Department of Energy–Program for Ecosystem Research Grant DE-FG02-08ER64510 (to N. J.S.), from National Science Foundation Grant DEB 0716966 (to A.V.S.), and from the New Zealand Foundation for Research, Science, and Technology Grant C09X0507 (to D.W.)

The increasing numbers of invasive species have stimulated the study of the underlying causes promoting the establishment and spread of exotic species. We tracked the spread of the highly invasive Argentine ant (Linepithema humile) along an environmental and habitat gradient on the northeastern Iberian Peninsula to determine the role of climatic, habitat and biotic variables on the rate of spread, and examine impact on native ant communities. We found the species well-established within natural environments. The mean annual rate of spread of the invasion (7.94 ± 2.99 m/year) was relatively low compared to other studies, suggesting that resistance posed by native ants in natural environments with no or low human disturbance might delay (although not prevent) the spread of the invasion irrespectively of the land-use type. Factors related to the distance to urban areas and characteristics of native and introduced populations explained the rate of spread of the invasion, while habitat-related variables determined the distribution of native ants and the impact of the Argentine ant on them. Native ant communities became more homogeneous following the invasion due to the decline of species richness and abundance. Only few species (Plagiolepis pygmaea and Temnothorax spp.) were able to cope with the spread of the invasion, and were possibly favored by the local extinction of other ant species. Taken together, our results indicate that land uses per se do not directly affect the spread of L. humile, but influence its invasive success by molding the configuration of native ant communities and the abiotic suitability of the site Financial support for this study came from Beatriu de Pino´s Postdoctoral Grant (2006 BP-A 10124) from the Catalan Agency for Management of University and Research Grants (in support of NRP), the Ministry of Education and Science of the Spanish Government CGL2004-05240-C02-02/BOS (NRP and JMB)

Determining the geographical range of invasive species is an important component of formulating effective management strategies. In the absence of detailed distributional data, species distribution models can provide estimates of an invasion range and increase our understanding of the ecological processes acting at various spatial scales. We used two complementary approaches to evaluate the influence of historical and environmental factors in shaping the distribution of the Argentine ant (Linepithema humile), a widespread, highly invasive species native to South America. Occurrence data were combined with environmental data at incremental spatial scales (extent and resolution) to predict the suitable range of the ant invasion using ecological niche models. In addition, we also used a spread model that simulated the jump dispersal of the species to identify the most plausible scenarios of arrival of L. humile in the NE Iberian Peninsula at local scales. Based on the results of both modelling practices, we suggest that L. humile might have reached its maximum geographic range at regional scales in the NE Iberian Peninsula. However, the species does not appear in equilibrium with the environment at small spatial scales, and further expansions are expected along coastal and inland localities of the Costa Brava. Long-distance jumps are ultimately responsible for the spread of the Argentine ant in the area. Overall, our study shows the utility of combining niche based models with spread models to understand the dynamics of species' invasions Financial support for this study came from Beatriu de Pino´s postdoctoral grant (2006 BP-A 10124) from Catalan Agency for Management of University and Research Grants (in support of NRP), the Ministry of Education and Science of the Spanish Government CGL2004-05240-C02-02/BOS (NRP and JMB).

8 páginas, 6 figuras, In the current global climate change scenario, stressors overlap in space and time, and knowledge on the effects of their interaction is highly needed to understand and predict the response and resilience of organisms. Corals, among many other benthic organisms, are affected by an increasing number of global change-related stressors including warming and invasive species. In this study, the cumulative effects between warming and invasive algae were experimentally assessed on the temperate reefbuilder coral Cladocora caespitosa. We first investigated the potential local adaptation to thermal stress in two distant populations subjected to contrasting thermal and necrosis histories. No significant differences were found between populations. Colonies from both populations suffered no necrosis after long-term exposure to temperatures up to 29°C. Second, we tested the effects of the interaction of both warming and the presence of invasive algae. The combined exposure triggered critical synergistic effects on photosynthetic efficiency and tissue necrosis. At the end of the experiment, over 90% of the colonies subjected to warming and invasive algae showed signs of necrosis. The results are of particular concern when considering the predicted increase of extreme climatic events and the spread of invasive species in the Mediterranean and other seas in the future., We thank the Secretaría General de Pesca (MAGRAMA) and the Columbretes Islands Marine Reserve staff for their logistic support. Support for this work was provided by a Ramon y Cajal research contract (RyC- 2011-08134) to C.L. and by a JAE-doc (FSE) to E.C. This study was funded by the Spanish Ministry of Economy and Innovation Smart project (CGL2012-32194).

Zebra mussel (Dreissena polymorpha, Pallas, 1771) is a bivalve mollusc species native from the Caspian and Black seas region. Since XIX century has expanded to central Europe, and it established in the Iberian Peninsula in 2001. The presence of D. polymorpha causes ecological impacts, affecting biodiversity, and economic impacts, blocking water-conductor infrastructures. In order to control and manage the infestation, different control and management plans have been established. Some of these organizations are Agencia Catalana de l’Aigua (ACA), Confederacion Hidrogràfica de l’Ebre (CHE), and Agencia Basca de l’Aigua (URA). These monitoring plans are carried out by observing larvae through a microscope, a technique with low specificity and sensitivity that can generate false positives. For this reason the molecular methods can be an alternative more reliable that could fix the problems like un-specificity and low sensitivity. Using gene histone H2B and Real-Time PCR, it is expected to be optimized a method to determine the infestation grade from environmental filtered-water samples. For do this, it’s necessary to optimize the previous steps, like DNA isolation and PCR amplification. The samples used in this project belong to different locations from Catalonia sampled in two seasons. Results obtained show that D. polymorpha DNA is present in all analysed locations. ACA has only confirmed the presence in one of them (La Baells Reservoir), suggesting the better molecular techniques specificity and sensitivity than traditional visual methods. We also have seen that in winter there are more D. polymorpha DNA prevalence in the water column than in summer, according with the reproduction period. This molecular analysis can be used like routine tool into the D. polymorpha control and management plans. Because its quickness and its great D. polymorpha DNA detection, the prevention efforts could be focussed to the locations with risk of infestation

The dynamic in Argentine ant colonies varies seasonally, influenced by biotic and abiotic factors. In winter the spatial range of the colony is contracted in large formations (winter nests) containing a large number of queens and workers. Winter nests are the clue to the species' dispersion power and the invasion of new habitats. For this reason a yearly elimination of queens and workers in winter at the edge (front) of the invasion could be a useful tool for weakening the species' dispersion and therefore limiting its establishment in new areas. Here, we determined the spatial dynamics of the Argentine ant nests during 1 year, and we assessed the invasion management by means of manual removal of winter nests for two consecutive winters, determining its effects during the following 3 years. We mapped nests found in 18 plots divided into two groups: extirpated (with removal of nests) and non-extirpated (control), along the fronts of three locations. Seasonal variation in the abundance of nests and workers, together with the two-year extirpation effects were evaluated. We found that colonies tended to follow an annual cycle of contraction and dispersion, with a decrease in the number of nests as we approached the invasion front. The extirpation was effective only in the front area, where it promoted smaller, less lasting and aggregated nests, as well as a decrease in the abundance of queens and workers. Nests also experienced a decrease during the two first winters but a recovery in the third, when no extirpation was done. Thus, a yearly perturbation should be performed to keep the expansion of the Argentine ant at a low rate, and to limit its establishment in new areas This work was financed by the Spanish Ministry of Science and Innovation with the support of a predoctoral grant (BES-2008-005102) associated with research projects MEC/FEDER2007-64080-C02-02/BOS and CGL2010-16451, and a FI grant from the European Social Fund and the DIUE of the Autonomous Government of Catalonia in support of MLE

Estudi promogut per la Direcció d'Espais Verds i Biodiversitat de l'Ajuntament de Barcelona, juntament amb el Consorci del Parc Natural de la Serra de Collserola i amb la col·laboració de la Gerència d'Espais Naturals de la Diputació de Barcelona, la Mancomunitat de Municipis de l'àrea Metropolitana de Barcelona, el gremi de jardiners, el gremi de viveristes, el CREAF (Centre de Recerca Ecològica i Aplicacions Forestals), l'APEVC (Associació de Professionals dels Espais Verds de Catalunya) i la Fundació de la Jardineria i el Paisatge

Es tracta de la correcció de l'article original publicat a Biology Letters, 2013, vol. 9, núm. 5, p. 20130540 Herewith, we retract our paper ‘How many and which ant species are being accidentally moved around the world?’ by Verónica Miravete et al., published online on 23 October 2013 (Biol. Lett. 9, 20130540; doi:10.1098/rsbl.2013.0540). After careful examination of the original data on introduced and established ants on regions worldwide, we realized that we used a wrong list of species and omitted to include a reference (Sarnat E. (2012) North America checklist. Antkey . Extracted 3 June 2014) in the paper. Although the main arguments and conclusions remain the same after correcting these errors, the use of the wrong version of the data affected the magnitude of the analyses conducted at the country level (in the electronic supplementary material) and, to a lesser extent, when all countries were considered together (in the main text). Therefore, we wish to retract the article. We deeply apologize for any inconvenience this publication might have caused to the readers of Biology Letters

Aquest article ha estat corregit posteriorment l'1 de juliol de 2014. Correcció a: Biology Letters, 2014, vol. 10, núm. 7, p. 20140504 Human transportation facilitates the dispersal of exotic ants, but few studies have quantified the magnitude and geography of these movements. We used several non-parametric indices to estimate the number of species successfully introduced to or established in new regions. We also compared their source biogeographic realms to assess the importance of geographical origin in determining the likelihood of establishment after introduction. Occurrence data on exotic ants derive from studies of three temperate regions. Our results suggest that the numbers of introduced orestablished ants may be much larger than the numbers so far documented. Ants introduced or established in new regions tend to arrive from the same or neighbouring realms, as would be expected if exotic species tend to match climates and if arrival/establishment is dependent upon higher trade rates from neighbouring countries V.M. and C. G. received support from MICINN (CGL2010-16451), N.R-P. from MICINN (CSD2008-00040) and R. R. D. from US DOE PER (DE-FG02-08ER64510), NASA Biodiversity (ROSES-NNX09AK22G) and NSF Career (0953390) grants

Study of the impacts of biological invasions, a pervasive component of global change, has generated remarkable understanding of the mechanisms and consequences of the spread of introduced populations. The growing field of invasion science, poised at a crossroads where ecology, social sciences, resource management, and public perception meet, is increasingly exposed to critical scrutiny from several perspectives. Although the rate of biological invasions, elucidation of their consequences, and knowledge about mitigation are growing rapidly, the very need for invasion science is disputed. Here, we highlight recent progress in understanding invasion impacts and management, and discuss the challenges that the discipline faces in its science and interactions with society., The workshop that spawned this paper was sponsored by CEFE-CNRS, the University of Montpellier (UM2) and the Région Languedoc Roussillon. P.P. was supported by grant no. P504/11/1028 (Czech Science Foundation), long-term research development project no. RVO 67985939 (Academy of Sciences of the Czech Republic), institutional resources of Ministry of Education, Youth and Sports of the Czech Republic, and acknowledges the support by Praemium Academiae award from the Academy of Sciences of the Czech Republic. D.A.W. was supported by a Wallenberg Scholars award, E.G.B. by the Spanish Ministry of Science (projects CGL2009-12877-C02-01 and CSD2009- 00065), M.V. by the Spanish Ministry of Science projects CGL2009-7515 and CSD2008-00040 and the Junta de Andalucıía RNM-4031, and F.C. by the French ANR (2009 PEXT 010 01)., info:eu-repo/semantics/publishedVersion

The Editorial presents the focus, scope, policies, and the inaugural issue of NeoBiota, a new open access peer-reviewed journal of biological invasions. The new journal NeoBiota is a continuation of the former NEOBIOTA publication series. The journal will deal with all aspects of invasion biology and impose no restrictions on manuscript size neither on use of color. NeoBiota implies an XML-based editorial workflow and several cutting-edge innovations in publishing and dissemination, such as semantic markup of and enhancements to published texts, data publication, and extensive cross-linking within the journal and to external sources. Fil: Kühn, Ingolf. Helmholtz Centre for Environmental Research; Alemania Fil: Kowarik, Ingo. Technische Universität Berlin; Alemania Fil: Kollmann, Johannes. Technische Universitat München; Alemania Fil: Starfinger, Uwe. Julius Kuehn Institute; Alemania Fil: Bacher, Sven. University of Fribourg; Suiza Fil: Blackburn, Tim. King Saud University; Arabia Saudita Fil: Bustamante, Ramiro. Universidad de Chile; Chile Fil: Celesti Grapow, Laura. Università degli studi di Roma "La Sapienza"; Italia Fil: Chytrý, Milan. Masaryk University; República Checa Fil: Colautti, Robert. University of Duke; Estados Unidos Fil: Essl, Franz. Environment Agency Austria; Austria Fil: Foxcroft, Llewellyn. South African National Parks; Sudáfrica. Stellenbosch University; Sudáfrica Fil: García Berthou, Emili. University of Girona; España Fil: Gollasch, Stephan. GoConsult; Alemania Fil: Hierro, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Hufbauer, Ruth. Colorado State University; Estados Unidos Fil: Hulme, Philip. Lincoln University; Estados Unidos Fil: Jarosik, Vojtech. Charles University in Prague; República Checa. Academy of Sciences of the Czech Republic; República Checa Fil: Jeschke, Jonathan. Ludwig Maximilians Universitat; Alemania Fil: Karrer, Gerhard. University of Natural Resources and Life Sciences Vienna; Austria Fil: Mack, Richard. Washington State University; Estados Unidos Fil: Molofsky, Jane. University of Vermont; Estados Unidos Fil: Murray, Brad. University of Technology Sydney; Australia Fil: Nentwig, Wolfgang. University of Bern; Suiza Fil: Osborne, Bruce. Universidad de Dublin; Irlanda Fil: Pysek, Petr. Charles University in Prague; República Checa. Academy of Sciences of the Czech Republic; República Checa Fil: Rabitsch, Wolfgang. Environment Agency Austria; Austria Fil: Rejmanek, Marcel. University of California at Davis; Estados Unidos Fil: Roques, Alain. Institut National de la Recherche Agronomique; Francia Fil: Shaw, Richard. CABI Europe; Reino Unido Fil: Sol, Daniel. Universitat Autònoma de Barcelona; España Fil: van Kleunen, Mark. Consejo Superior de Investigaciones Científicas; España Fil: Vilà, Montserrat. University of Konstanz; Alemania Fil: von der Lippe, Moritz. Technishe Universitat Berlin; Alemania Fil: Wolfe, Lorne. Georgia Southern University; Estados Unidos Fil: Penev, Lyubomir. Pensoft Publishers; Bulgaria

The influence of temperature on the developmental times and survival of insects can largely determine their distribution. For invasive species, like the Argentine ant, Linepithema humile Mayr (Hymenoptera: Formicidae), these data are essential for predicting their potential range based on mechanistic models. In the case of this species, such data are too scarce and incomplete to make accurate predictions based on its physiological needs. This research provides comprehensive new data about brood survival and developmental times at a wide range of temperatures under laboratory conditions. Temperature affected both the complete brood development from egg to adult worker and each of the immature stages separately. The higher the temperature, the shorter the development times. Brood survival from egg to adult was low, with the maximum survival rate being only 16% at 26 degrees C. Temperature also affected survival of each of the immature stages differently: eggs were negatively affected by high temperatures, while larvae were negatively affected by low temperatures, and the survival of pupae was apparently independent of environmental temperature. At 32 degrees C no eggs survived, while at 18 degrees C less than 2% of the eggs hatched into larva. The data from the present study are essential for developing prediction models about the distribution range of this tramp species based on its physiological needs in relation to temperature.

Alien species invading freshwater systems are causing major changes in biodiversity worldwide. Some alien species have been used as indicators of water quality and environmental degradation. We discuss the reasons for monitoring invasive species beyond their use as ecological indicators, and offer guidance on the design of appropriate long-term monitoring schemes. Monitoring plays an essential role in providing an early warning system, because eradication of alien species at the early stages of invasion is more effective and less costly than when the invader is established. Monitoring the presence of aliens is also more effective when associated to monitoring the vectors known to transport them, and is equally valuable after eradication and to determine the effects management and whether restoration has been achieved. Scientifically, monitoring an invasion in conjunction with measuring other abiotic and biotic parameters provides baseline information on the dynamics of the invasion, the vulnerability of the habitat to invasion and on the impacts of the invader. Combining information on the patterns of invasion with that of the regional environmental factors operational at the time is relevant to establishing relationships between the invasion and other global change components. Overall, the long-term monitoring of biological invasions, that integrates information before, during and after an invasion provides valuable information for both managers and scientists

To address the lack of physiological approaches in current models assessing the potential distribution of the Argentine ant, we used data on brood development from distinct sources to evaluate a series of degree-day models for Catalonia (NE Iberian Peninsula), and data on the brood survival and oviposition rates to develop a worker production model. The degree-day model generated using data from Newell and Barber (1913) and Benois (1973) indicated that the number of degree-days required for the complete development from egg to adult worker was 445.4 degree-days above a threshold of 15.9 °C, while the model calibrated using data from Abril et al. (2008, in press) suggested 599.5 degree-days above 18.4 °C. Comparisons between the degree-day model predictions and the currently known distribution of the Argentine ant suggested that the one generated using data from Newell and Barber (1913) and Benois (1973) overestimated the presence of the species, while the one calibrated using data from Abril et al. (2008; in press) underestimated it. On the other hand, the predicted daily net production of Argentine ant workers generated by the worker production model predicted more accurately the distribution of the Argentine ant than the degree-day models. Our results show the utility of incorporating physiological data in models to assess the distribution limits of the Argentine ant, which up to date have taken little account of the physiological needs of the species in terms of its establishment and dispersion in its introduced ranges This study was financed by the Spanish Ministry of Education and Science (CGL2004-05240-C02-02/BOS and MEC/FEDER2007-64080-C02-02/BOS). S. Abril acknowledges support from the University of Girona, and N. Roura-Pascual from the Catalan Agency for Management of University and Research Grants (Generalitat de Catalunya) through a Beatriu de Pino´ s Postdoctoral Grant (2006 BPA 10124)

The Argentine ant, Linepithema humile, is a world-wide invasive ant species. Its presence has a strong negative impact on ant diversity. The present study attempts to highlight the reasons for the coexistence of this highly dominant species with Plagiolepis pygmaea, the only native ant species that has proved able to resist the invasion in a natural ecosystem in the north-east of the Iberian Peninsula. To quantify the aggressiveness level of both species we performed aggressiveness tests on workers in different areas: a) Argentine ant workers from areas with P. pygmaea, b) Argentine ant workers from areas without P. pygmaea, c) P. pygmaea from a non-invaded area and d) P. pygmaea from an invaded area. We also confronted Argentine ant workers with P. pallidula and T. nigerrimum. These aggressiveness tests showed that the coexistence of these two species of ants was not due to a habituation process, since the aggressiveness level observed between the four kinds of confrontations were fairly similar. We also found a lack of aggressiveness between Argentine ant workers and P. pygmaea, and highly submissive behavior in the latter when confronted with the invader. The peaceful character of P. pygmaea together with its markedly submissive behavior may be the main factors behind the coexistence of these species in the study area

The zebra mussel (Dreissena polymorpha, Pallas, 1771) is one of the most invasive species of freshwater bivalves, due to a combination of biological and anthropogenic factors. Once this species has been introduced to a new area, individuals form dense aggregations that are very difficult to remove, leading to many adverse socioeconomic and ecological consequences. In this study, we identified, tested, and validated a new set of polymorphic microsatellite loci (also known as SSRs, Single Sequence Repeats) using a Massive Parallel Sequencing (MPS) platform. After several pruning steps, 93 SSRs could potentially be amplified. Out of these SSRs, 14 were polymorphic, producing a polymorphic yield of 15.05%. These 14 polymorphic microsatellites were fully validated in a first approximation of the genetic population structure of D. polymorpha in the Iberian Peninsula. Based on this polymorphic yield, we propose a criterion for establishing the number of SSRs that require validation in similar species, depending on the final use of the markers. These results could be used to optimize MPS approaches in the development of microsatellites as genetic markers, which would reduce the cost of this process

Modeling ecological niches of species is a promising approach for predicting the geographic potential of invasive species in new environments. Argentine ants (Linepithema humile) rank among the most successful invasive species: native to South America, they have invaded broad areas worldwide. Despite their widespread success, little is known about what makes an area susceptible - or not - to invasion. Here, we use a genetic algorithm approach to ecological niche modeling based on high-resolution remote-sensing data to examine the roles of niche similarity and difference in predicting invasions by this species. Our comparisons support a picture of general conservatism of the species' ecological characteristics, in spite of distinct geographic and community contexts

Aquest article va ser corregit l'1 de juliol de 2014. La correcció es va publicar a Biology Letters, 2014, vol. 10, núm. 7, p. 20140504 Human transportation facilitates the dispersal of exotic ants, but few studies have quantified the magnitude and geography of these movements. We used several non-parametric indices to estimate the number of species successfully introduced to or established in new regions. We also compared their source biogeographic realms to assess the importance of geographical origin in determining the likelihood of establishment after introduction. Occurrence data on exotic ants derive from studies of three temperate regions. Our results suggest that the numbers of introduced or established ants may be much larger than the numbers so far documented. Ants introduced or established in new regions tend to arrive from the same or neighbouring realms, as would be expected if exotic species tend to match climates and if arrival/establishment is dependent upon higher trade rates from neighbouring countries V.M. and C.G. received support from MICINN (CGL2010-16451), N.R-P. from MICINN (CSD2008-00040) and R.R.D. from US DOE PER (DE-FG02-08ER64510), NASA Biodiversity (ROSES-NNX09AK22G) and NSF Career (0953390) grants

Charles Elton was a founder of ecology with fundamental contributions to diverse topics such as fluctuations of animal populations, food web theory, or what is now known as the Eltonian definition of the ecological niche (Macfadyen 1992; Simberloff 2000; Hardy 2002). His 1927 book Animal Ecology was reprinted many times and he was the first editor of the Journal of Animal Ecology. One of Elton’s most influential contributions, however, was his book The ecology of invasions by animals and plants, first published in 1958. Although many earlier authors including Darwin had dealt with invasive species, this book has been considered the starting point for focused scientific attention on biological invasions and is the most cited reference in the field (Pysek et al. 2006; Richardson and Pysek 2007; Ricciardi and MacIsaac 2008; Richardson and Pysˇek 2008) I thank the Editor-in-Chief, D. Simberloff, for helpful comments and the Spanish Ministry of Education for financial support (CGL2006-11652-C02/BOS)

The present study attempts to analyse the aggressive behaviour of the two European supercolonies of the Argentine ant, Linepithema humile, in confrontations between them and with several native ant species, to assess if there are differences in their aggressiveness, and consequently, in their competitive ability. Workers from the Main supercolony were more aggressive than workers from the Catalan supercolony. They showed a higher significant aggressiveness index in confrontations with workers from the Catalan supercolony and with two of the three native ant species studied: in Tapinoma nigerrimum (NYLANDER, 1856) and Lash's cinereus SEIFERT, 1992, but not in Pheidole pallidula (NYLANDER, 1849). They also mainly initiated the aggressive encounters and responded aggressively to attacks during confrontations both with the Catalan supercolony and with the native ant species. As compared to the Main supercolony, workers from the Catalan one showed a reduced aggressive behaviour in confrontations with the native ant species studied. Moreover, the native ant species attacked workers from the Catalan supercolony more frequently than workers from the Main one. These results may support the hypothesis of a weaker competitive ability of the Catalan supercolony, and therefore, a minor invasiveness power, and could also partially explain why that super-colony is clearly less widely distributed throughout Europe than the Main supercolony This study was financed by the Spanish Ministry of Education and Science (MEC/FEDER2007-64080-C02-02/BOS and CGL2010-16451)

Understanding the invasion process of an exotic species could be useful to manage its dispersion in natural habitats. To that effect, we provide new data on the queens' biological and physiological characteristics in Linepithema humile (MAYR, 1868) colonies from both the invasion front (contact area) and the totally invaded area (invaded area) in order to examine the differences between them. We analyze: 1) queen densities per liter of nest soil, 2) fat content (%), 3) oviposition rates, and 4) the queen / worker thorax volume ratios of individuals from nests situated in the contact and invaded zones. All these parameters are good estimators of the invasive capabilities of colonies, as they are related to dispersion speed and successful colony foundation. Although we did not detect physiological differences in the fat content and oviposition rates of queens from the two zones, we found evidence of differences in the social structure of nests (queen densities) and in the morphology of queens (queen / worker thorax volume ratios) between nests from the invasion's contact and invaded zones. In the former there were bigger queens and higher queen densities than in the latter. Those differences are probably a response to the different ecological contexts of the two zones and would provide the colonies in the contact zone of the invasion with a higher invasiveness potential for competing with the native ant community for empty niches and resources This study was financed by the Spanish Ministry of Education and Science (MEC/FEDER2007-64080-C02-02/BOS and CGL2010-16451). Mireia Diaz acknowledges support from the Spanish Ministry of Science and Innovation for the BES-2008-005102 pre-doctoral grant linked to the CGL2007-64080-C02-02 research project, and Martha Lucia Enriquez from the European Social Fund and the DIUE of the Autonomous Government of Catalonia for her FT pre-doctoral grant

The annual elimination of large numbers of Argentine ant queens near the advance front of an invasion could be a useful tool for weakening the species’ dispersion and, therefore, limiting its establishment in non-invaded areas. However, before carrying out trials to test the effectiveness of this method it would be essential to have sufficient knowledge of the effect of seasonal dynamics acting on the queens’ densities of the species in order to determine the most favourable period of the year to act. We analyzed the seasonal densities and nest dynamics of Argentine ant queens in an invaded Mediterranean natural ecosystem. We observed that the queens’ density varied depending on the season of the year and that this variation was mainly due to the seasonal dynamics of nest aggregations in winter and ant dispersions in summer. The greatest densities per litre of nest soil were observed in winter (December to March, approximately) and the lowest densities were observed in summer ( June to July). This information is essential for improving current knowledge of the Argentine ant’s biology and developing control methods based on the elimination of queens in invaded natural areas

The Argentine ant, Linepithema humile (MAYR, 1868), shows a cycle of regrouping of its nests in winter. Nests are located in similar sites every year, with a high density of queens in winter. We measured the physical characteristics, temperature and water content of 90 winter nests and control points, from December 2008 to March 2010. Additionally, we carried out a bimonthly monitoring of nest site fidelity throughout 2009 and in winter of 2009 / 2010. All studies were conducted in two invaded areas of the north-eastern Iberian Peninsula. The objective was to determine the preferred places for this species to build its nests in winter. Our results showed that nest location was influenced primarily by soil moisture, temperature and the vegetation around. Soil moisture inside nests was regulated mainly by temperature which in turn was controlled by orientation, rock color and canopy cover above the nest site. Canopy cover was related to the distance at which the nests were from plant structures, providing them a close food resource. Additionally, canopy cover could also play a two-side role helping to avoid high levels of soil moisture and extreme temperatures inside nests. Nest orientation and rock color may also help to protect the colony from extreme temperatures as well as to capture sunlight to provide an additional heat source maintaining optimal environmental conditions inside the nest, but also for colony activity during winter. Knowledge of the Argentine ant's nesting behavior is essential to initiate control methods such as the extirpation of winter nests with the consequent elimination of high densities of queens and their brood in invaded natural areas his work was financed by the Spanish Ministry of Science and Innovation with the support of a predoctoral grant (BES-2008-005102) associated with research projects MEC / FEDER2007-64080-C02-02 / BOS and CGL2010-16451, and a FT grant from the European Social Fund and the DIUE of the Autonomous Government of Catalonia in support of MLE