Emerging and invasive tree pests and pathogens in Europe are increasing in number and range, having impacts on biodiversity, forest services, ecosystems and human well-being. Stakeholders involved in tree and forest management contribute to the detection and management of new and emerging tree pests and pathogens (PnPs). We surveyed different groups of stakeholders in European countries. The stakeholders were mainly researchers, tree health surveyors and forest managers, as well as forest owners, nurseries, policy-makers, advisors, forestry authorities, NGOs and civil society. We investigated which tools they used to detect and manage PnPs, surveyed their current PnP awareness and knowledge and collated the new and emerging PnP species of concern to them. The 237 respondents were based in 15 European countries, with the majority from the United Kingdom, France and the Czech Republic. There was a strong participation of respondents with a work focus on research and surveying, whereas timber traders and plant importers were less represented. Respondents were surveyed on 18 new, emerging PnPs in Europe and listed an additional 37 pest species and 21 pathogen species as potential future threats. We found that species on EPPO’s list of ‘priority pests’ were better known than those not listed. Stakeholders working in urban environments were more aware of PnPs compared to those working in rural areas. Stakeholders’ awareness of PnPs was not related to the number of new, emerging PnP species present in a country. Stakeholders want access to more detection and management tools, including long-term citizen-science monitoring, maps showing spread and range of new PnPs, pest identification smartphone apps, hand-held detection devices, drone monitoring and eDNA metabarcoding. To help facilitate better forest health across Europe, they called for mixed forest development, reduced nursery stock movement, biosecurity and data sharing amongst organisations. These results indicate that stakeholder knowledge of a few key PnP may be good, but given that the large diversity of threats is so large and future risks unknown, we conclude that multiple and varied methods for generic detection, mitigation and management methods, many in development, are needed in the hands of stakeholders surveying and managing trees and woodlands in Europe.

According to the Latitudinal Biotic Interaction Hypothesis (LBIH), the general increase in biodiversity towards lower latitudes can be partially explained by an increase in the intensity of biotic interactions. While LBIH received some support for plant-herbivores interactions, much less is known about how higher trophic levels may contribute to shape biotic interactions across latitudinal gradients. We hypothesized that the diversity of insectivorous birds increases towards lower latitude, leading to higher predation rates on insect herbivores. We deployed plasticine caterpillars in 138 oak trees in 47 sites along a 19 degree latitudinal gradient in Europe to quantify bird insectivory through predation attempts. In addition, we used passive acoustic monitoring to (i) characterize the acoustic diversity of surrounding soundscapes; and (ii) infer both taxonomic and functional diversity of insectivorous birds from recordings. The functional diversity of insectivorous birds increased towards lower latitude. Bird predation increased with latitude, forest cover and bird acoustic diversity but decreased with mean annual temperature and functional richness of insectivorous birds. Contrary to our predictions, latitudinal clines in bird predation attempts were not directly mediated by changes in insectivorous bird diversity or acoustic diversity, but latitude and habitat still had independent effects on predation attempts. Our study does not fully support the predictions of the LBIH of more biotic interactions southwards and advocates for better accounting for activity and abundance of insectivorous birds when studying the large-scale variation in insect-tree interactions.