Global movement of woodwasps (Hymenoptera: Siricidae) inferred from border interception records

Abstract

Global trade has accelerated the spread of wood-boring insects. Woodwasps (Hymenoptera: Siricidae) include several species that have established outside their native ranges, but their global translocation is not well documented. Despite several biases, port interception records can serve as indirect proxies of propagule pressure and can be used to quantify invasion pathways. Here, we use historical border interception records from the USA (1914–2020), Canada (1997–2019), and New Zealand (1950–2007) to infer global transport pathways and propagule pressure of siricids. We compiled 3054 interception records, identifying dominant species, source biogeographical regions, and associated commodities. Interceptions were overwhelmingly linked to wood packaging materials, confirming this pathway as the principal vector of introduction. Most of the intercepted woodwasp species originated from the European and Asian Palearctic regions, indicating these areas as major historical sources of propagule pressure. However, increasing records from non-native regions suggest possible secondary introductions from previously established non-native populations (i.e., bridgehead regions). Despite frequent interceptions, only a subset of species has established, highlighting mismatches between propagule pressure and invasion success, likely mediated by ecological constraints on establishment such as host availability and climate. Our results demonstrate the value of long-term interception datasets for reconstructing invasion pathways, while emphasizing their limitations due to taxonomic uncertainty and sampling bias. Improving species identification and standardizing biosecurity data collection could enhance the use of interception records for invasion risk assessment and management.

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