Invasive Plants Push Around Native Ants

Have you ever been stung by a fire ant? Even if you haven’t, you probably know how (supposedly) bad and evil fire ants are. Yet fire ants, and a couple other well-known invasive ant species like Argentine ants, are only a few out of about 13,000 known species of ants, and they give all of these other species a bad rap. So today, let’s look at a new study by co-first authors Kevin Li and Yifan He and colleagues that properly flips the script: invasive plants push around friendly native ants.

The big bad shrub, Elaeagnus umbellata

The researchers investigated the relationship between the expansion of the mean shrub, Elaeagnus umbellata, and the local geographic range of an ant nobody hates, Formica obscuripes. In their words, “by comparing the ant’s landcover preferences before and after the invasion, we demonstrate that this species experienced a significant unfavorable change in its foraging areas.” Because of this, the authors predict that the number and size of F. obscuripes nests will decline over the next four decades.

F. obscuripes ants trying to mind their own business. Photo: Alex Wild

In order to demonstrate these findings, Li, He, and colleagues utilized a map of F. obscuripes nest distributions in a Michigan reserve created by Dr. Mary Talbot in 1980. These sort of resources are invaluable for addressing modern questions about the impacts of biological invasions and climate change, and illustrate the importance of “basic” natural history information for understanding and eventually solving current and future environmental problems. Assuming that funding for such research doesn’t disappear, it will be instructive to see other ways in which invasive plants impact our favorite ant communities.