Invasive alien species as reservoirs for pathogens

Alien plant and animal hosts play an important role as vectors of dangerous pathogens. However, the knowledge on pathogens of many host species is still limited. To bridge this gap, we collated information on pathogens carried by 118 alien species in Europe in their native and secondary range. In Europe, these species are considered as invasive. Using the dataset we determined most prevailing pathogen groups and plant and animal hosts that carried the highest number of pathogens. The most numerous pathogens were bacteria Xylella fastidiosa (plants) and Rabies virus (animals). The principal pathogen groups among plant hosts were Arthropoda (phylum), Insecta (class) and Hemiptera (order), and among animal hosts – Platyhelminthes (phylum), Trematoda (class) and Plagiorchiida/Strongylida (order). In plants, the highest number of pathogens was recorded for Ambrosia artemisiifolia; in animals, Procyon lotor was the most infested species. Hosts introduced from North America carried the highest numbers of pathogen species; in addition, unintentionally introduced hosts carried more pathogens than those introduced intentionally. We revealed also that the level of infestation differs between the habitats in which the hosts occur. It should be also stressed that in all analyses the number of pathogens increased with the number of publications on the particular host’ infestation. The highest number of publications was available for species useful for human, such as Crassostrea gigas. The results demonstrated that there are still significant gaps in the knowledge on the role of other hosts, including invasive ones (e.g., Sciurus niger) in pathogen transmission. © 2022 Institute of Nature Conservation, Polish Academy of Sciences