A bioavailable strontium (87Sr/86Sr) isoscape for Aotearoa New Zealand: Implications for food forensics and biosecurity.

As people, animals and materials are transported across increasingly large distances in a globalized world, threats to our biosecurity and food security are rising. Aotearoa New Zealand is an island nation with many endemic species, a strong local agricultural industry, and a need to protect these from pest threats, as well as the economy from fraudulent commodities. Mitigation of such threats is much more effective if their origins and pathways for entry are understood. We propose that this may be addressed in Aotearoa using strontium isotope analysis of both pests and products. Bioavailable radiogenic isotopes of strontium are ubiquitous markers of provenance that are increasingly used to trace the origin of animals and plants as well as products, but currently a baseline map across Aotearoa is lacking, preventing use of this technique. Here, we have improved an existing methodology to develop a regional bioavailable strontium isoscape using the best available geospatial datasets for Aotearoa. The isoscape explains 53% of the variation (R2 = 0.53 and RMSE = 0.00098) across the region, for which the primary drivers are the underlying geology, soil pH, and aerosol deposition (dust and sea salt). We tested the potential of this model to determine the origin of cow milk produced across Aotearoa. Predictions for cow milk (n = 33) highlighted all potential origin locations that share similar 87Sr/86Sr values, with the closest predictions averaging 7.05 km away from their true place of origin. These results demonstrate that this bioavailable strontium isoscape is effective for tracing locally produced agricultural products in Aotearoa. Accordingly, it could be used to certify the origin of Aotearoa's products, while also helping to determine if new pest detections were of locally breeding populations or not, or to raise awareness of imported illegal agricultural products.

Japanese Aedes albopictus among four mosquito species reaching New Zealand in used tires.

Since a 1988-89 survey of northern New Zealand revealed no additions to the known mosquito fauna, this country's used tire importations have much increased. Relevant entomological quarantine was thus monitored in a November 1992-January 1993 Auckland project, during which almost 1/3 of 8,549 casings from Japan proved wet on inspection. In this study and at 2 South Island ports afterwards, 5 vessels from Japan and one from Australia were found to have brought in mosquito-infested used tires. Live Aedes albopictus (all larval instars, pupae, and adults) and Aedes japonicus, and dead Tripteroides bambusa were discovered in shipments from Japan (3 interceptions each in the first 2 cases, and one in the 3rd). Live Tripteroides tasmaniensis were recorded from the Australian cargo. One of the Ae. albopictus arrivals was followed by an apprehended introduction at an Auckland importer's premises.