First record of Arionvulgaris Moquin-Tandon, 1855 (Arionidae) from Armenia

Background

Arionvulgaris Moquin-Tandon, 1855 is amongst the fastest-spreading terrestrial slugs Europe-wide. In recent years, it has been recorded in Canada, Mexico and continues to expand eastwards into Eurasia. Renowned for its high invasiveness, combatting its swift spread creates significant challenges in organising effective preventative measures.

New information

This study presents the first record of Arionvulgaris from Armenia, which is the second record of this species' invasion of the Caucasus. In 2022, a substantial population of A.vulgaris was observed close to the City of Stepanavan, which is also the first record in Armenia of the family Arionidae. How the species was introduced to Armenia remains unknown. Identification of Arionvulgaris was conducted, based on external and genital morphology and mitochondrial CO1 (cytochrome c oxidase subunit 1) gene sequencing, revealing notable similarities with Central European clades. Our results confirm the introduction and distribution of A.vulgaris to Armenia. Invasion of such species into Armenia will require additional monitoring and would be aided by further research on Armenia's mollusc fauna in the future.

When One's Not Enough: Colony Pool-Seq Outperforms Individual-Based Methods for Assessing Introgression in Apis mellifera mellifera

The human management of honey bees (Apis mellifera) has resulted in the widespread introduction of subspecies outside of their native ranges. One well known example of this is Apis mellifera mellifera, native to Northern Europe, which has now been significantly introgressed by the introduction of C lineage honey bees. Introgression has consequences for species in terms of future adaptive potential and long-term viability. However, estimating introgression in colony-living haplodiploid species is challenging. Previous studies have estimated introgression using individual workers, individual drones, multiple drones, and pooled workers. Here, we compare introgression estimates via three genetic approaches: SNP array, individual RAD-seq, and pooled colony RAD-seq. We also compare two statistical approaches: a maximum likelihood cluster program (ADMIXTURE) and an incomplete lineage sorting model (ABBA BABA). Overall, individual approaches resulted in lower introgression estimates than pooled colonies when using ADMIXTURE. However, the pooled colony ABBA BABA approach resulted in generally lower introgression estimates than all three ADMIXTURE estimates. These results highlight that sometimes one individual is not enough to assess colony-level introgression, and future studies that do use colony pools should not be solely dependent on clustering programs for introgression estimates.

Occurrence and abundance of invasive and native Arion slugs in three types of habitats in urban area of Wrocław (SW Poland)

Arion vulgaris and Arion rufus are two cryptic slug species whose ranges overlap in vast areas of Europe. In Poland, A. rufus is native; it reaches the eastern border of its range near Wrocław, while the invasive A. vulgaris was previously not recorded in this area. The study aimed to map the distribution of both species in the city of Wrocław and determine the size and abundance of their populations. Twenty-six sites were surveyed in 2019-2020. They represented three types of habitats: natural, semi-natural and anthropogenic. Because the investigated species are externally indistinguishable, their identification was based on the genital organs. Among 280 analysed specimens, 72% were identified as A. vulgaris, 23% as A. rufus and 5% were classified as hybrids. The hybrids and A. vulgaris were most abundant in semi-natural (83%) and anthropogenic habitats (95%), while A. rufus most often occurred in natural habitats (51%). Arion vulgaris occupied most of the sites (88.5%), and in 50%, it was collected alone. Arion rufus occurred in 46% of the sites (in 11.5% alone), and the hybrids were noted in 27%. In Wrocław A. vulgaris dominates in most sites, and its populations are much more abundant than those of A. rufus where the two species co-occur. This finding indicates that A. vulgaris, with its better adaptive skills and competitive abilities, may negatively impact the native species and, consequently, the latter’s displacement. Although the recorded frequency of hybridisation was very low (5%), it may also have an effect on the local extinction of A. rufus. Interspecific hybridisation is assumed to foster invasions, and climate change may further exacerbate displacement; therefore, they should continue to be monitored.