Fast range expansion of the red imported fire ant in Virginia and prediction of future spread in the United States

Abstract

AbstractThe red imported fire ant (RIFA),Solenopsis invicta(Buren), is a notorious, invasive species with broad impacts on ecosystems, economies, and human health. While incidental reports to the Virginia Department of Agriculture and Consumer Services (VDACS) indicate a recent range expansion in Virginia, the full extent of RIFA spread in the area is currently unknown. In this study, we examined the distribution of RIFA in Virginia using multiple data sources: (1) during the summers of 2020 and 2021, we conducted a series of prospective visual surveys along public roadways in southern Virginia, (2) we used data from multiyear VDACS infestation reports covering the period 2016–2021, and (3) we surveyed local naturalists, county extension agents, and land managers. We compared the resulting data with an earlier predictive model quantifying the potential spread of RIFA and constructed a species distribution model to explore the potential range expansion of RIFA in the United States based on new occurrence data and bioclimatic variables. RIFA was found in seven Virginia counties beyond the current federal quarantine zone, and our data show that it has spread much further than predicted 15 years ago. Our species distribution model suggests that the range of RIFA is likely to increase further under the currently projected climate change scenarios, both in Virginia and more generally across the United States, with the lower Midwest expected to be one of the most affected areas. This study provides insights into the range expansion of RIFA at the border of its suitable North American habitat and elucidates some of the environmental factors associated with its current and future spread. In doing so, it provides information to advise sound management practices and prevention efforts.