Knowledge mapping of world's worst invasive alien species under changing climate.

SUMMARYAnts are among the worst invasive species, and can have tremendous negative impacts on native biodiversity, agriculture, estates, property and human health. Invasive ants are extremely difficult to control, and thus early detection is essential to prevent ant invasions, in particular through surveillance efforts at ports of entry. This paper assesses the potential distribution of 14 of the worst invasive ant species in France, under current and future climatic conditions. Consensus species distribution models, using five different modelling techniques, three global climate models and two CO2 emission scenarios, indicated that France presented suitable areas for 10/14 species, including five listed on the Invasive Species Specialist Group's selection of the world's 100 worst invasive species. Among these 10 species, eight were predicted to increase their potential range with climate change. Areas with the highest concentration of potential invaders were mainly located along the coastline, especially in the south-west of France, but all departments appeared to be climatically suitable for at least two invasive species. A ranking of climatic suitability per species for 17 major airports and 14 maritime ports indicated that the ports of entry with the highest suitability were located in Biarritz, Toulon and Nice, and the species with the greatest potential distribution in France were Lasius neglectus and Linepithema humile, followed by Solenopsis richteri, Pheidole megacephala and Wasmannia auropunctata.

Ants figure prominently among the worst invasive species because of their enormous ecological and economic impacts. However, it remains to be investigated which species would be behaviourally dominant when confronted with another invasive ant species, should two species be introduced in the same area. In the future, many regions might have suitable environmental conditions for several invasive ant species, as predicted under climate change scenarios. Here, we explored interactions among several highly invasive ant species, which have been shown to have overlapping suitable areas. The aim of this study was to evaluate the performance in interference competition of seven of the world’s worst invasive ant species (Anoplolepis gracilipes, Paratrechina longicornis, Myrmica rubra, Linepithema humile, Lasius neglectus, Wasmannia auropunctata and Pheidole megacephala). We conducted pairwise confrontations, testing the behaviour of each species against each of the six other species (in total 21 dyadic confrontations). We used single worker confrontations and group interactions of 10 versus 10 individuals to establish a dominance hierarchy among these invasive ant species. We discovered two different behavioural strategies among these invasive ants: three species displayed evasive or indifferent behaviour when individuals or groups were confronted (A. gracilipes, Pa. longicornis, M. rubra), while the four remaining species were highly aggressive during encounters and formed a linear dominance hierarchy. These findings contrast with the widespread view that invasive ants form a homogeneous group of species displaying the ‘invasive syndrome’, which includes generally aggressive behaviour. The dominance hierarchy among the four aggressive species may be used to predict the outcome of future competitive interactions under some circumstances. Yet, the existence of several behavioural strategies renders such a prediction less straightforward.

While there has been great interest in species characteristics that promote invasiveness, still little is known about the characteristics that distinguish invasive from non‐invasive insects. Using a database on the naturalised distributions of alien insects and expert opinions about their impacts, we identified the world's 100 worst invasive insect species. By comparing species characteristics reported in the literature using a meta‐analysis, between the 100 worst invasive species and related non‐invasive species, we found that invasive insects overall have more pathways of introduction, occur in more habitats, have higher fecundities, higher voltinism, more genes, shorted lifespans and faster development from egg to adult. Some of the differences in species characteristics related to propagule pressures, life‐histories and biotic interactions, conditional on whether the non‐invasive species compared is known to be naturalised somewhere, whether the invasive species is globally distributed, and the climatic region of the species. Synthesis and applications. We show for the first time, using a multi‐species comparative approach, that invasive insects differ in several characteristics from related non‐invasive insects. Our results show that invasive species, such as Spodoptera frugiperda, typically are habitat generalists with a high fecundity, a short lifespan and fast development, whereas the importance of female body size and number of enemies are context dependent. Our study can guide and improve existing screening tools for assessing the invasion potential of alien insects.

There has been an increasing demand for alien fish species in India. However, environmental, socioeconomic and biodiversity issues are important considerations when regulating the unauthorized culture and spread of alien species. Information collected in the present review revealed the presence of over 300 alien species imported intentionally or illegally; 291 ornamental species, 31 aquaculture species and two larvicidal fishes. Field data demonstrated the widespread occurrence of some of the world’s worst invasive species, for example, Cyprinus carpio, Oreochromis niloticus, Aristichthys nobilis, Pygocentrus nattereri and Pterygoplichthys spp., in inland waters; other species are emerging as a threat to aquatic biodiversity. The benefits and risks of alien species were analysed and the impact was quantified using a simple developed ‘Fish Invasiveness Screening Test’ (FIST). Our information suggests that alien species, despite possessing some attractive culture characteristics, generally reduce the availability of local species and establish in natural water bodies becoming invasive and consequently adversely affecting fish biodiversity and aquatic ecosystems. In light of the adverse ecological impacts of alien species, we developed strategic regulations and quarantine procedures and advised aquaculturists to strictly follow them to contain potential and plausible menaces.

Invasive non-native species are an important cause of biodiversity loss, particularly in fresh waters. The mosquitofish Gambusia holbrooki are among the world’s worst invasive species: they have caused extirpations of native species and are known to sometimes cause trophic cascades and ecosystem effects. This invasive species is also known to impact threatened fishes such as the Spanish toothcarp (Aphanius iberus), which is endemic to Mediterranean Spain. However, it is unclear if the impact of mosquitofish on many fishes is more through resource competition, agonistic interactions or predation, and how often mosquitofish cause trophic cascades. To clarify these questions, we performed a 48-day mesocosm experiment in eutrophic conditions to test for interspecific effects and clarify the impact mechanism using six treatments: the two fish species alone each at two densities, and the two fish species mixed or separated with a net that prevented direct interactions among them. We observed clear fish treatment effects on several variables. At low initial fish densities, the population growth rate of mosquitofish was orders of magnitude greater than that of the Spanish toothcarp, likely contributing to its invasive success and ecological impact. At high fish densities, turbidity, chlorophyll a concentration and daytime dissolved oxygen percentage increased, whereas total phosphorus decreased; crucially, the trophic cascade caused by mosquitofish was stronger than that by toothcarp. The experiment also demonstrated that the interspecific effects of mosquitofish on toothcarp were more important than those of intraspecific competition. The invasive species produced effects on population growth rate, size structure, and fish condition (mass-length relationship) of toothcarp. Effects on population growth rate of toothcarp seem more caused by resource competition, whereas impacts on size structure and condition seem also caused by more direct interactions. The diversity of effects of mosquitofish underscores the difficulty of predicting the impact of invasive species. Our study further provides an approach to differentiate the effects of resource competition from other more direct ecological interactions and so to clarify the impact mechanism of aquatic invasive species.

Biological invasions are synonymous with international trade. The direct effects of trade have largely been quantified using relationships between imports and the number of alien species in a region or patterns in the global spread of species linked to shipping and air traffic networks. But trade also has an indirect role on biological invasions by transforming the environments and societies of exporting and importing nations. Here, both the direct and indirect roles of trade on biological invasions, as well as their interaction, are examined for the first time. Future trends in international trade, including e-commerce, new trade routes, and major infrastructure developments, will lead to the pressure on national borders soon outstripping the resources available for intervention. The current legislative and scientific tools targeting biological invasions are insufficient to deal with this growing threat and require a new mindset that focuses on curbing the pandemic risk posed by alien species.

Rabbits are considered by biologists to be among the worst invasive species. Their impact on invaded ecosystems, epitomized in Australia and on islands worldwide (e.g. North, Bullock & Dulloo, 1994; Williams et al., 1995; Burbidge & Moris, 2001; Garzon-Machado et al., 2010), has earned them a well-deserved place in the infamous Invasive Species Specialist Group’s ‘100 of the Worst Invasive Alien Species’ list. Rabbits are capable of profoundly altering communities, ecosystems and landscapes by sapping biodiversity and biomass from the basic trophic levels of often fragile ecosystems. However, they also have more complex, and hitherto seldom documented effects on higher trophic levels (Zedler & Black, 1992; Priddel, Carlile & Wheeler, 2000; Oliver, LuqueLarena & Lambin, 2009; Denyer, Hartley & John, 2010). In the context of a few, but loud voices attempting to question the importance of alien invasive species (but see Lambertini et al., 2011; Lockwood, Hoopes & Marchetti, 2011), the paper by Brodier et al. (2011) is well timed. It reminds us that restoration ecology and the fight against biodiversity loss are possible, in particular on islands, as they generally have many endemic and threatened species. This paper also highlights two very important, yet previously overlooked points. The first is the importance of longterm follow-up after restoration programmes. The second is the need to consider the indirect (and consequently often hidden) effects that alien invasive species can have on seemingly unconnected species. By monitoring the populations, several petrel species and their avian predator (the brown skua, Catharacta skua) following the removal of rabbits, Brodier et al. (2011) show that rabbits compete for space with blue petrels, Halobaena caerulea. Following rabbit eradication, the competition for burrows was removed and the blue petrel population increased up to eightfold in a few generations. Brown skua also increased their survivorship in response to the increase in its main prey, the blue petrel. Interestingly, the population of another petrel, the Antarctic prion, Pachyptila desolata, was also impacted by the rabbits. Following the eradication, the Antarctic prion population declined fourfold (to exclusion) in areas of deep soil and remained stable where the soil was too shallow for blue petrel (and rabbits). The resulting system, illustrated in Fig. 1, shows that one unexpected, and up to now unreported, effect of rabbits was to erode the niche partitioning of nesting seabirds on the island. Removing the rabbits led to both a competitor release (of the blue petrel, freed from the competition with rabbits) and to an apparent competitor release (of the shared predator, the brown skua, boosted by increased blue petrel availability). The combination of direct and indirect interactions restricted Antarctic prions to shallow soil areas, less favoured by the blue petrel. This neat system shows how alien invasive species can have effects beyond the trophic level constituting their resources. The contrast between the spectacular recovery of the blue petrel, the increased survival but stable number of skua breeding pairs and the decrease of the Antarctic prion also illustrates well the difficulties to forecast outcomes that conservation program may face even in relatively simple trophic webs. This is especially so in the current context of global climate change, which already affects subantarctic islands (Chapuis, Frenot & Lebouvier, 2004; Dowding et al., 2009), and which could have played a role in the system, for example, in the delayed recovery of the skua. Monitoring population densities, survival and predator diet, every year, on this remote, far reaching island, for long after the rabbit eradication might have been seen as a risky bet. As it turned out, the bet paid off, in the best currency ever: knowledge and understanding. Deciphering the indirect effects a terrestrial herbivore can have on a community of seabirds with which they have few interactions if any, is crucial in our battle against alien invasive species (Bergstrom et al., 2009; Genovesi, 2011). It demonstrates very well that if we were to ‘judge alien species only on their effects’, we would miss all but the tip of the iceberg and would allow important but unapparent, indirect effects of alien invasive species on native ecosystems. One regret from this study is that the monitoring effort conducted after rabbit eradication was not also implemented Animal Conservation. Print ISSN 1367-9430

The spread of invasive alien plants has considerable environmental and economic consequences, and is one of the most challenging ecological problems. The spread of invasive alien plant species depends largely on long-distance dispersal, which is typically linked with human activity. The increasing domination of the internet will have impacts upon almost all components of our lives, including potential consequences for the spread of invasive species. To determine whether the rise of Internet commerce has any consequences for the spread of invasive alien plant species, we studied the sale of thirteen of some of the most harmful Europe invasive alien plant species sold as decorative plants from twenty-eight large, well known gardening shops in Poland that sold both via the Internet and through traditional customer sales. We also analyzed temporal changes in the number of invasive plants sold in the largest Polish internet auction portal. When sold through the Internet invasive alien plant species were transported considerably longer distances than for traditional sales. For internet sales, seeds of invasive alien plant species were transported further than were live plants saplings; this was not the case for traditional sales. Also, with e-commerce the shape of distance distribution were flattened with low skewness comparing with traditional sale where the distributions were peaked and right-skewed. Thus, e-commerce created novel modes of long-distance dispersal, while traditional sale resembled more natural dispersal modes. Moreover, analysis of sale in the biggest Polish internet auction portal showed that the number of alien specimens sold via the internet has increased markedly over recent years. Therefore internet commerce is likely to increase the rate at which ecological communities become homogenized and increase spread of invasive species by increasing the rate of long distance dispersal.

The last decade has seen a rapid development of scientific, logistic and tourist activities, especially in the Antarctic region with the mildest climatic conditions: the Antarctic Peninsula. This region is also exhibiting rapid regional warming and all of the already diagnosed alien species in the Antarctic Treaty Area were found within the Antarctic Peninsula. Identifying potential invasive species that can threaten this pristine area of the Earth helps us to take specific preventive actions. This article is a commentary on Hughes et al., 26, 2702-2716.

Invasive alien species and planetary and global health policy

Extent of plant invasions has been expected to be low in protected areas such as national parks due to low anthropogenic activities and high wilderness. However, recent researches across the world have revealed that plant invasions can be severe in the national parks with negative impacts on the protected species and ecosystems. Unfortunately, the status of plant invasions in the national parks of Nepal is mostly unknown. In this study, we sampled at seven locations inside the Parsa National Park (PNP) to document diversity and abundance of invasive alien plant species (IAPS) and their impacts on tree regeneration. Altogether, 130 quadrats of 10 m × 10 m were sampled. We recorded 14 IAPS in the PNP. Three of the IAPS (Chromolana odorata, Lantana camara and Mikania micrantha) were among the 100 of the world’s worst invasive alien species. C. odorata was found to be the most frequent IAPS with the highest cover. The frequency and cover of the IAPS were higher at the sites close to the settlements than at the sites away from the settlements. The species richness of the IAPS was also higher at the sites closer to the settlements than away. The sapling density of the tree species was found to have declined with the increasing cover of the IAPS suggesting that the IAPS had negatively affected tree regeneration. Our data revealed that the PNP has already witnessed massive plant invasions with widespread occurrence of three of the world’s worst invasive species. Therefore, it is high time to integrate management of invasive alien species in the management plan of the park.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 562:101-111 (2016) - DOI: https://doi.org/10.3354/meps11944 Interactive effects of ocean warming and acidification on sperm motility and fertilization in the mussel Mytilus galloprovincialis Angela R. Eads*, W. Jason Kennington, Jonathan P. Evans Centre for Evolutionary Biology, University of Western Australia, Crawley, WA 6009, Australia *Corresponding author: angela.eads@graduate.uwa.edu.au ABSTRACT: Gametes of marine broadcast spawners are highly susceptible to the threats of ocean warming and acidification. Here, we explore the main and interacting effects of temperature and pH changes on sperm motility and fertilization rates in the mussel Mytilus galloprovincialis. Additionally, we determine how temperature and pH interact to influence the motility of aging sperm. We show that the interactive effects of temperature (18°C or 24°C) and pH (ranging from 7.6 to 8.0) on sperm motility depend on the time that sperm spend in these conditions. Specifically, sperm linearity was influenced by a temperature × pH interaction when measured after a relatively short exposure to the treatment conditions, while main effects of temperature and pH (but no interaction) on sperm motility became apparent only after prolonged exposure (2 h) to the treatments. Despite the interactive effects of temperature and pH on sperm motility, these factors had independent effects on fertilization rates, which were significantly higher at the ambient ocean pH level and at the elevated temperature. This study highlights the importance of considering the combined effects of predicted ocean changes on sperm motility and fertilization rates, and cautions against using only sperm motility as a proxy for reproductive fitness. Detrimental effects of pH and temperature may only be uncovered when these factors are examined together, or conversely, negative impacts of one variable may be buffered by changes in another. Our results raise the intriguing possibility that some species may cope better with ocean acidification if they simultaneously experience ocean warming. KEY WORDS: Ocean acidification · Ocean warming · Sperm motility · Fertilization · Broadcast spawner Full text in pdf format Supplementary material PreviousNextCite this article as: Eads AR, Kennington WJ, Evans JP (2016) Interactive effects of ocean warming and acidification on sperm motility and fertilization in the mussel Mytilus galloprovincialis. Mar Ecol Prog Ser 562:101-111. https://doi.org/10.3354/meps11944 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 562. Online publication date: December 29, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

In the early 1900s, eastern mosquitofish (Gambusia holbrooki) and western mosquitofish (Gambusia affinis) were deliberately and globally introduced for the biological control of mosquito larvae. Subsequently, both species developed a reputation for causing impacts on native small-bodied fish, amphibian larvae, and other aquatic species. This led to both species being considered some of the world’s worst invasive species. Due to morphological similarities, organizations worldwide often consider these species jointly when discussing their introduction and impacts. Recent studies suggest these species differ in fundamental ways, which could affect invasion success. Our goal was to compare eastern and western mosquitofish behavior and invasion success. Replicate populations were collected from the U.S. states of Florida (eastern mosquitofish) and Louisiana (western mosquitofish) to assess variation in aggression, boldness, and sociability. Mesocosm trials were used to compare invasion success between species following introduction to an ecosystem occupied by another small-bodied poeciliid. Eastern mosquitofish caused more damage to similar-sized heterospecifics and western mosquitofish exhibited greater boldness. No differences were found in sociability between the two species. In mesocosms, impacts were observed for both mosquitofish species but were greatest for heterospecifics with eastern mosquitofish. This suggests that two invasive species, even with similar life history and morphology, can differ in traits related to invasion success and ecological impacts. It is important to correctly identify mosquitofish species when evaluating their invasion.

One of the primary tools for raising awareness on biological invasions has been the publication of species accounts of the most prominent alien invaders. Until now such compilations have been available only for particular taxa, biomes and/or regions (Cronk and Fuller 2001; Weber 2003; Weidema 2000). In Europe, species accounts for selected invasive species have been published for a few countries or regions: the Czech Republic (Mlíkovský and Stýblo 2006), France (Pascal et al. 2006), Italy (Andreotti et al. 2001; Scalera 2001), Spain (Capdevila-Argüelles and Zilletti 2006); the Mediterranean Sea (CIESM 2007), and the North European and Baltic region (Gollasch et al. 1999; NOBANIS 2007). These accounts highlight invasive alien species which cause significant harm to biological diversity, socio-economic values and human health in these regions. The main purpose of these accounts is to provide guidance to environmental managers and raise public awareness of the biological, ecological and socio-economic impacts of the most harmful invaders, together with a description of the main management options to prevent their spread and reduce their impacts. The importance of the role of such tools has been clearly shown by the IUCN's 100 of the World's Worst Invasive Species list (Love et al. 2000) which has been very influential in raising awareness and supporting the development of policy conservation instruments relevant to biological invasions (Shine et al. 2000). The European Environmental Agency has produced, within the SEBI 2010 project, a list of the worst invasive alien species threatening biological diversity in Europe (EEA 2007). This list contributes to the general indicator of changes in biological diversity caused by invasive alien species. The SEBI 2010 list is primarily a means to communicate the issue of invasive species to policymakers, stakeholders and the general public. The selection of the 168 species on the list was carried out in an open consultative process with an expert group, the scientific community and national environmental authorities. The main criterion used for selection was that the species have a serious impact on biological diversity at the regional level. Serious impact implies that the species has severe effects on ecosystem structure and function, it can replace native species throughout a significant proportion of its range, it can hybridise with native species or threaten biodiversity. In addition, the species can have negative consequences for human activities, health and/or economic interests.

Native plant communities are often invaded by multiple alien species. It is still unclear how increasing diversity of alien invasive species suppresses the growth of native species and thus contributes to invasion success. In the subtropical monsoon region of southeast China, we experimentally created a native plant community with 18 herbaceous species. One week later, we let it be invaded by either zero (controls without invasion), one, two, four or eight alien plant species, with either high or low species evenness. After a four‐month growth period we harvested the aboveground biomass of each species. We found that increasing invasive species richness significantly increased invasive plant biomass, the biomass of all invasive and native plant species within the community, and invasion success (the ratio of invasive plant biomass to the biomass of all native and invasive plants), but it did not significantly reduce native plant biomass. Experimentally manipulating invasive species evenness did not influence invasion success and did not show any differential suppression effects on native plants. One invasive species, Sesbania cannabina , became dominant in terms of plant biomass, irrespective of its proportion in the alien plant mixtures. Throughout this experiment, effects of invasive species richness on invasion success were mainly due to such selection effects among the invasive species. On the other hand, the unchanged biomass of native species under increasing invasive plant richness suggests the presence of at least partly complementary resource niches between invasive and native species.