Invasive alien species are a major driver of global change, impacting biodiversity, ecosystem services, and human livelihoods. To document these impacts, we present the Global Impacts Dataset of Invasive Alien Species (GIDIAS), a dataset on the positive, negative and neutral impacts of invasive alien species on nature, nature’s contributions to people, and good quality of life. This dataset arises from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services’ (IPBES) thematic assessment report of this topic. Data were compiled from published sources, including grey literature, reporting a direct observation of an invasive alien species’ impact. All impact records contain up to 52 fields of contextual information and attempt to link impacts to the global standard “environmental impact classification for alien taxa” (EICAT) and “socio-economic impact classification for alien taxa” (SEICAT). GIDIAS includes more than 22000 records of impacts caused by 3353 invasive alien species (plants, vertebrates, invertebrates, microorganisms) from all continents and realms (terrestrial, freshwater, marine), extracted from over 6700 sources. We intend GIDIAS to be a global resource for investigating and managing the variety of impacts of invasive alien species across taxa and regions.

Early detection and rapid response are essential to deal effectively with new introductions of invasive alien species (IAS). Citizen science platforms for opportunistic recording of species are increasingly popular, and there is potential to harvest their data for early detection of IAS, but this has not been tested. We evaluated the potential of data from existing citizen science platforms for early detection of IAS by obtaining 687 first records of species from 30 European countries where there was both an official first record (i.e. published in scientific literature or by a government agency) and a record in a citizen science platform. We tested how the difference between the two (time lag) was related to species traits, popularity in citizen science platforms, public and research attention and regulatory status. We found that for 50% of the time lag records, citizen science platforms reported IAS earlier than or in the same year as the official databases. Although we cannot determine causality (the first official record could have been from a citizen science platform, or contemporaneous with it), this demonstrates that citizen science platforms are effective for IAS early detection. Time lags were largely affected by species traits. Compared with official records, vertebrates were more likely to have earlier records on citizen science platforms, than plants or invertebrates. Greater popularity of the IAS in citizen science platforms and its observation in neighbouring countries resulted in earlier citizen science reporting. In contrast, inclusion in the EU priority list resulted in earlier official recording, reflecting the efficacy of targeted surveillance programmes. However, time lags were not affected by the overall activity of citizen platforms per country. Synthesis and applications. Multi‐species citizen science platforms for reporting nature sightings are a valuable source of information on early detection of IAS even though they are not specifically designed for this purpose. We recommend that IAS surveillance programmes should be better connected with citizen science platforms, including greater acknowledgement of the role of citizen scientists and better data flow from smaller citizen science initiatives into global databases, to support efficient early detection. Read the free Plain Language Summary for this article on the Journal blog.

Biological invasions represent one of the main drivers of biodiversity loss with adverse impacts on human societies, economies and public health. More than 500 ant species have been transported outside their native range with the help of humans, while the majority of them have managed to establish viable populations in the wild. Nevertheless, data from the Mediterranean region suggest that most alien ants occupy anthropogenic habitats with little spread in semi-natural and natural habitats. Research on biological invasions of ants in Greece had previously identified a total of 15 alien ant species. In this article, an extensive literature investigation and material examination provide a revised checklist of the alien myrmecofauna of Greece. Although the number of alien ant species remains the same, the checklist’s composition is largely altered to provide an up-to-date overview of the country’s alien myrmecofauna in order to enhance management decisions and future research. The presence and distribution of alien ants within Greek administrative divisions, NATURA 2000 sites and Corine Land Cover types are analysed and presented. In particular, the species richness of alien ants seems to be highest in the Aegean Archipelago (Crete and Southern Aegean Islands) probably due to uneven collecting efforts and increased climatic suitability. Alien ant species are mostly associated with anthropogenic habitats including urban and agricultural areas, although a significant percentage has managed to spread into forest and semi-natural areas, including protected NATURA 2000 sites. Future research directions enhancing the monitoring of alien ants and their impacts are indicated to safeguard native ant biodiversity and conservation efforts of rare and endemic taxa.

Invasive alien species have been increasingly acknowledged as a major threat to native biodiversity and ecosystem services, while their adverse impacts expand to human health, society and the economy on a global scale. Insects represent one of the most numerous alien organismic groups, accounting for about one fifth of their total number. In Greece, a large number of alien insects have been identified, currently reaching 469 species. In recent decades, the contribution of citizen science towards detecting and mapping the distribution of alien insects has been steeply increasing. Addressing the need for up-to-date information on alien species as well as encouraging public participation in scientific research, the Alientoma website—derived from “alien” and the Greek word “entoma”, meaning insects, is presented. The website aims towards providing updated information on alien species of insects to the public as well as the scientific community, raising awareness about biological invasions and addressing their distribution and impacts inter alia. By maintaining a dynamic online database alongside a strong social media presence since its launch, Alientoma has attracted individuals mainly from Greece and Cyprus, interacting with the website through a total of 1512 sessions. Alientoma intends to establish a constantly increasing network of citizen scientists and to supplement early detection, monitoring and management efforts to mitigate the adverse impacts of alien insects in Greece.

Alien invasive species not only have adverse environmental impacts, they may also pose socioeconomic and human health threats. The increase in detected non-native (alien) and cryptogenic species, followed by the necessity for up-to-date scientific information on biological invasions, prompted a thorough literature investigation on the non-native entomofauna of Greece. Supplementing previous studies concerning Europe and Greece, a checklist for the non-native insect species of the country is provided, while their number is elevated from 266 to 469. Current trends regarding species richness and taxonomy, deliberate or accidental means of introduction, as well as their native range and trophic preferences are analysed and discussed. This publication illustrates the current state of non-native insects of Greece, highlighting the need for an effective early warning system integrated in national phytosanitary legislation, survey protocols and strategies towards the eradication and mitigation of their detrimental impacts.

Native to E. Asia, the box tree moth Cydalima perspectalis (Walker, 1859) has managed to establish itself, and gradually expand its distribution, across Europe, Asia and recently America. This publication documents the first known record of the invasive species in Africa. The moth was observed in Constantine, Algeria in 2018 and was later identified as C. perspectalis. Possible scenarios of its introduction on the continent, as well as potential ecological implications, are discussed.