An ecological risk assessment of the establishment of the asian giant hornet (vespa mandarinia) in the pacific northwest

Abstract

The recent introduction of the Asian giant hornet (Vespa mandarinia) in the United States in late 2019 has raised concerns about the establishment of the insect in the Pacific Northwest, and its potential deleterious effects to honey bees and their pollination services in the region. Therefore, I conducted a risk assessment to estimate the risk of establishment of V. mandarinia in Washington and Oregon on a county by county basis. To assess these risks, my assessment used the risk assessment framework put forth by the U.S. National Research Council. The risk assessment relied on the biological requirements and ecological relationships of V. mandarinia in the environments of the Pacific Northwest. I based the risk characterization on climate and habitat suitability estimates for V. mandarinia queens to overwinter and colonize nests, density and distribution of apiaries, and locations of major human-mediated introduction pathways that may increase the risk of establishment of the hornet in the counties of Washington and Oregon. My results suggest that 70 of the 75 counties in the region could be at medium to high risk of establishment by the hornet. Many of the western counties of both Washington and Oregon were estimated to be at the highest risk of establishment, mainly due to their suitable climate for queens to overwinter, dense forest biomass for nest colonization, and proximity to major port and freight hubs in the region. Considering its negative effects, these counties should be prioritized in ongoing monitoring and eradication efforts of the insect.