Abstract
International trade poses a growing threat to global biosecurity, with bark- and wood-boring beetles representing a major concern for forest health. Non-native species are frequently introduced at points of entry, where populations can establish in the surrounding landscape. To improve early detection, generic surveillance programs use traps in these high-risk areas, collecting a broad spectrum of species. These traps also capture native beetles, providing insights into the potential species pool that could become exotic elsewhere. However, implementing effective landscape-wide surveillance within reasonable resource limits remains challenging. In this study, we used trapping data of Cerambycidae and Scolytinae from 11 high-risk areas across Europe and North America to develop practical recommendations for generic surveillance at multiple spatial scales. Specifically, we attempted to address two key questions: (1) how to maximize the single-trap efficacy depending on the trap surroundings; and (2) how many traps should be used in a landscape-wide sampling depending on landscape composition. Under budget constraints, we recommend prioritizing trap placement within forest patches and avoiding locations surrounded by roads or buildings. Urban-dominated landscapes required greater sampling effort (i.e., more traps) than forest-dominated landscapes. Deploying fewer than four traps per square kilometer might lead to an incomplete representation of the local bark- and wood-boring beetle community, losing about 30%-50% of species. Overall, our findings highlight the importance of incorporating landscape ecology into generic surveillance planning to optimize trap effectiveness within resource limitations.