Invertebrate interceptions at Australia's borders: a nine-year assessment of trends and biosecurity challenges

The introduction of non-native invertebrates poses a significant threat to Australia’s environment, biodiversity, agricultural industries, and socio-economic wellbeing, necessitating robust biosecurity measures to prevent their establishment. Global trade and transport are major pathways for these incursions, monitored through national biosecurity interception programs. We analysed nine years of interception records from Australia’s national biosecurity invertebrate interceptions dataset (2016–2024), to examine temporal, taxonomic, and pathway trends, providing a novel overview spanning all terrestrial invertebrate taxa. We observed temporal fluctuations in detection frequency, with invertebrates most frequently intercepted between November and February. Interceptions decreased significantly in 2020, following the international border closure as a result of COVID-19, and although the total number of interceptions varied significantly across pre-, during-, and post-COVID periods, species richness remained stable over time. While 2,414 unique species were identified, they represented only 40.5% of intercepted specimens. Furthermore, over the nine years, the diversity of intercepted and identified species showed no signs of plateauing. This underscores the need for ongoing surveillance, efficient taxonomic identification, and standardised data collection across Australia. Analyses of this dataset revealed that interceptions are influenced by commodities of trade and passenger movement, and the trade in live animals, including the smuggling of exotic pet species. We recommend continued enhancements to biosecurity protocols, including more comprehensive interception records and resources to support rapid risk assessments of new emerging non-native species, to strengthen Australia’s existing ability to mitigate the risks associated with invasive invertebrates.