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.

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.

Citizen science is emerging as a powerful tool for the early detection of biological invasions. The exotic pet trade has been deemed as the most significant cause of establishment for reptiles, and among them, turtles have the highest number of introduction events. In Europe, at least 13 species of alien freshwater turtles have been recorded in the wild. In Greece, only two species of alien turtles have been reported, namely the American pond slider Trachemys scripta and the Florida cooter Pseudemys floridana. In this study, we provide an updated checklist of the alien freshwater turtles recorded in Greece, using citizen science, personal observations, and literature. Our results provide the first records for the country of five species, namely the Florida red-bellied cooter Pseudemys nelsoni, the Eastern river cooter Pseudemys concinna, the Chinese stripe-necked turtle Mauremys sinensis, the Chinese soft-shelled turtle Pelodiscus sinensis, and the Common snapping turtle Chelydra serpentina and new localities for T. scripta. Similar to the myth of the Lernaean Hydra (i.e., for every head chopped off, more would regrow), the pet turtle trade has been proven to have multiple heads.

The feather-legged fly, Trichopoda pennipes (Fabricius, 1781), is a parasitoid species introduced in several European countries over the last decades. This study provides new records for the presence of the tachinid in Mediterranean and Black Sea coastal areas. Four individuals were observed by the authors in Greece and Cyprus (2015-2019) and 11 additional records of the fly in Albania, Cyprus, Greece, Russia, and Turkey (2011-2019) were obtained from citizen science platforms. We provide the first records of the species on the aforementioned countries, contributing in the expansion of the current distribution range of the species. Current and future hypothetical expansion scenarios, as well as potential ecological implications are presented and discussed.

When two putatively cryptic species meet in nature, hybrid zone analysis can be used to estimate the extent of gene flow between them. Two recently recognized cryptic species of banded newt (genus Ommatotriton) are suspected to meet in parapatry in Anatolia, but a formal hybrid zone analysis has never been conducted. We sample populations throughout the range, with a focus on the supposed contact zone, and genotype them for 31 nuclear DNA SNP markers and mtDNA. We determine the degree of genetic admixture, introgression, and niche overlap. We reveal an extremely narrow hybrid zone, suggesting strong selection against hybrids, in line with species status. The hybrid zone does not appear to be positioned at an ecological barrier, and there is significant niche overlap. Therefore, the hybrid zone is best classified as a tension zone, maintained by intrinsic selection against hybrids. While the two banded newt species can evidently backcross, we see negligible introgression and the pattern is symmetric, which we interpret as supporting the fact that the hybrid zone has been practically stationary since its origin (while extensive hybrid zone movement has been suggested in other newt genera in the region). Our study illustrates the use of hybrid zone analysis to test cryptic species status.