DOI: 10.3897/neobiota.103.159848

Authors: Thomas J. Verleye, Thomas R. H. Kerkhove, Gert Van Hoey, Hans Pirlet, Francis Kerckhof, Ann-Katrien Lescrauwaet, Leen Vandepitte, Jan Mees

Abstract: Based on a thorough literature review and expert consultation, this study provides an inventory of all introduced non-indigenous species (iNIS) reported for Belgian marine and brackish waters. The data indicate a strong increase in iNIS in the study area from the 1990s onward, averaging 2.2 newly detected species per year, with a cumulative total of 108 iNIS between 1800 and 2024. The majority of these iNIS have the Northwestern Pacific or Northwestern Atlantic as their native region and are primarily introduced in Western Europe via shipping or aquaculture. In addition to compiling the inventory, the context in which the iNIS are detected is examined, distinguishing between official monitoring programs, project-based data collection efforts, and citizen science initiatives. Our findings indicate that while the EU aims to promote coordination between its Marine Strategy Framework Directive (MSFD) and Water Framework Directive (WFD), a misalignment occurs in the practical implementation of iNIS monitoring at the Belgian level. For example, a coherent and integrated monitoring framework across marine, brackish, and freshwater systems is still lacking. Furthermore, despite the EU’s ambition to ensure comprehensive iNIS monitoring, no legal framework currently mandates targeted monitoring in coastal ports, despite their well-documented role as hotspots for new marine introductions. After all, iNIS monitoring is only mandatory under the MSFD, which in essence applies only seaward from the coastal baseline and therefore does not cover waters within these ports. In addition, while the EU’s IAS Regulation has recently incorporated a few marine species on the Union list, its monitoring requirements remain primarily focused on terrestrial and freshwater species. As a result, observations published by citizens with significant expertise in the field represent the primary source of marine iNIS data in coastal port areas in recent decades in Belgium. The fragmentary nature of iNIS data complicates the efficient flow of information to international or European iNIS reference databases that support policy and decision-making. Yet, even species officially reported by Member States under MSFD Descriptor 2 are not always included in these reference databases. Nonetheless, accurate data on iNIS presence and distribution are essential for effectively targeting and managing iNIS.

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DOI: 10.3897/neobiota.98.139097

Authors: Róbert Gallé, Ágota Réka Szabó, Edina Török, Tamás Lakatos, Dávid Korányi, Attila Torma, Nikolett Gallé-Szpisjak, Péter Batáry

Abstract: Habitat fragmentation has far-reaching negative impacts on the environment, resulting in biodiversity loss, soil quality degradation and alteration of water availability. In addition, fragmentation can disrupt ecological processes, potentially facilitating the establishment and spread of invasive plants, which can further harm native arthropod communities and alter their ecosystem dynamics. However, the exact nature of these impacts may vary depending on local conditions. We investigated the impact of fragmentation and milkweed invasion on invertebrate communities in sandy grasslands of forest-steppe habitats in Hungary. We selected 30 grasslands in forest-steppe fragments, varying in size (0.2 to 8.7 ha) and connectivity (Hanski’s connectivity index: 0 to 705). We sampled ground-dwelling arthropods, mainly herbivores (true bugs) and predators (spiders), with pitfall traps and pollinators (wild bees) by direct observations along transects in invaded vs. non-invaded patches (min. of 500 m2) of each fragment. We considered arthropod species’ body size (all groups), dispersal ability and feeding (herbivores and predators) and nesting location and social habit (wild bee) traits in our analyses. In non-invaded patches, the number of monophagous herbivores showed an increasing trend, whereas in invaded fragments, there were more polyphagous individuals with increasing connectivity and fragment size. The dispersal ability of predators was lower as connectivity increased in non-invaded patches but higher in patches invaded by milkweed. We found more ground nesting bees in the invaded patches of small fragments than in large fragments, however, we did not find a significant effect in non-invaded patches. In summary, we often found interacting effects of the studied variables, fragmentation and invasions, generally modifying each other’s effect by filtering for opposite trait levels. The primary objective of restoration projects should be restoring habitat of appropriate size and connectivity and eradicating invasive species while concurrently supporting the revival of native species and their ecological relationships. It is essential to employ adaptive management techniques, including continuous monitoring, to effectively tackle the interaction between fragmentation, invasion, and the preservation of biodiversity.

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DOI: 10.3897/neobiota.82.96599

Authors: Saskya van Nouhuys, David C. Harris, Ann E. Hajek

Abstract: Parasitic nematodes and hymenopteran parasitoids have been introduced and used extensively to control invasive Eurasian Sirex noctilio woodwasps in pine plantations in the Southern Hemisphere where no members of this community are native. Sirex noctilio has more recently invaded North America where Sirex-associated communities are native. Sirex noctilio and its parasitic nematode, Deladenus siricidicola, plus six native hymenopteran woodwasp parasitoids in New York and Pennsylvania, were sampled from 204 pines in 2011–2019. Sirex noctilio had become the most common woodwasp in this region and the native parasitoids associated with the native woodwasps had expanded their host ranges to use this invader. We investigated the distributions of these species among occupied trees and the interactions between S. noctilio and natural enemies as well as among the natural enemies. Sirex noctilio were strongly aggregated, with a few of the occupied trees hosting hundreds of woodwasps. Nematode parasitism was positively associated with S. noctilio density, and negatively associated with the density of rhyssine parasitoids. Parasitism by the parasitoid Ibalia leucospoides was positively associated with host (S. noctilio) density, while parasitism by the rhyssine parasitoids was negatively associated with density of S. noctilio. Thus, most S. noctilio come from a few attacked trees in a forest, and S. noctilio from those high-density trees experienced high parasitism by both the invasive nematode and the most abundant native parasitoid, I. l. ensiger. There is little evidence for direct competition between the nematodes and parasitoids. The negative association occurring between rhyssine parasitoids and I. l. ensiger suggests rhyssines may suffer from competition with I. l. ensiger which parasitize the host at an earlier life stage. In addition to direct competition with the native woodwasp Sirex nigricornis for suitable larval habitat within weakened trees, the large S. noctilio population increases the parasitoid and nematode populations, which may increase parasitism of S. nigricornis.

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DOI: 10.3897/neobiota.67.58834

Authors: Corey J. A. Bradshaw, Andrew J. Hoskins, Phillip J. Haubrock, Ross N. Cuthbert, Christophe Diagne, Boris Leroy, Lindell Andrews, Brad Page, Phill Cassey, Andy W. Sheppard, Franck Courchamp

Abstract: The legacy of deliberate and accidental introductions of invasive alien species to Australia has had a hefty economic toll, yet quantifying the magnitude of the costs associated with direct loss and damage, as well as for management interventions, remains elusive. This is because the reliability of cost estimates and under-sampling have not been determined. We provide the first detailed analysis of the reported costs associated with invasive species to the Australian economy since the 1960s, based on the recently published InvaCost database and supplementary information, for a total of 2078 unique cost entries. Since the 1960s, Australia has spent or incurred losses totalling at least US$298.58 billion (2017 value) or AU$389.59 billion (2017 average exchange rate) from invasive species. However, this is an underestimate given that costs rise as the number of estimates increases following a power law. There was an average 1.8–6.3-fold increase in the total costs per decade since the 1970s to the present, producing estimated costs of US$6.09–57.91 billion year-1 (all costs combined) or US$225.31 million–6.84 billion year-1 (observed, highly reliable costs only). Costs arising from plant species were the highest among kingdoms (US$151.68 billion), although most of the costs were not attributable to single species. Of the identified weedy species, the costliest were annual ryegrass (Lolium rigidum), parthenium (Parthenium hysterophorus) and ragwort (Senecio jacobaea). The four costliest classes were mammals (US$48.63 billion), insects (US$11.95 billion), eudicots (US$4.10 billion) and monocots (US$1.92 billion). The three costliest species were all animals – cats (Felis catus), rabbits (Oryctolagus cuniculus) and red imported fire ants (Solenopsis invicta). Each State/Territory had a different suite of major costs by species, but with most (3–62%) costs derived from one to three species per political unit. Most (61%) of the reported costs applied to multiple environments and 73% of the total pertained to direct damage or loss compared to management costs only, with both of these findings reflecting the availability of data. Rising incursions of invasive species will continue to have substantial costs for the Australian economy, but with better investment, standardised assessments and reporting and coordinated interventions (including eradications), some of these costs could be substantially reduced.

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DOI: 10.3897/neobiota.55.48498

Authors: Julien Pétillon, Kaïna Privet, George K. Roderick, Rosemary G. Gillespie, Don K. Price

Abstract: We assessed how assemblages of spiders were structured in small Hawaiian tropical forest fragments (Hawaiian, kipuka) within a matrix of previous lava flows, over both space (sampling kipuka of different sizes) and time (comparison with a similar study from 1998). Standardized hand-collection by night was carried out in May 2016. In total, 702 spiders were collected, representing 6 families and 25 (morpho-)species. We found that the number of individuals, but not species richness, was highly correlated with the area of sampled forest fragments, suggesting that kipuka act as separate habitat islands for these predatory arthropods. Species richness was significantly lower in the lava matrix outside the kipuka compared to the kipuka habitats, although there was no statistical difference in species composition between the two habitats, largely because of similarity of non-native species in both habitats. Over the last 20 years, the abundance of non-native spider species substantially increased in both kipuka and lava habitats, in marked contrast to the vegetation that has remained more intact. With endemicity of terrestrial arthropods reaching over 95% in native forests, non-native predatory species present a critical challenge to the endemic fauna.

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DOI: 10.3897/neobiota.42.31582

Authors: Tobias Bauer, Stephan Feldmeier, Henrik Krehenwinkel, Carsten Wieczorrek, Nils Reiser, Rainer Breitling

Abstract: The Noble False Widow, Steatoda nobilis (Thorell, 1875) (Araneae, Theridiidae), is, due to its relatively large size and potential medical importance, one of the most notable invasive spider species worldwide. Probably originating from the Canary Islands and Madeira, the species is well established in Western Europe and large parts of the Mediterranean area and has spread recently into California and South America, while Central European populations were not known until 2011. We report on long-time observations that reveal that at least two flourishing populations in Germany (Cologne) have been present for over five years, while in Ecuador one population has been observed between 2014 and 2018 and several other records were made in other parts of the country. Data obtained from the British Spider Recording Scheme demonstrate that the species moved significantly northwards since the report of the first populations in the very South of England, after several decades of relative stasis. The sudden northward expansion highly correlates with a massive rise in press coverage of the species. In the Americas, S. nobilis is currently known from four countries (USA, Chile, Ecuador, Colombia), and available DNA barcoding data obtained for specimens from this area suggest that multiple introductions occurred within each country. Using ecological niche modeling, we identified suitable climate regions for the species and discuss possible reasons for its current spread. We propose that seaside cities and villages with a temperate oceanic or Mediterranean climate are especially favourable potential habitats for S. nobilis and will face the highest colonization pressure in the future, while tropical upland regions with temperate climates are also vulnerable to invasion by S. nobilis.

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