The news about European fire ants invading North America is getting worse.
These small, red‑brown ants were first discovered in Massachusetts over a hundred years ago. Since then, their populations have spread to humid regions of New England, New York, eastern Pennsylvania and southeastern Canada. First reports of them stinging people in Maine occurred in the late ‘60s. Their sting is not only painful, it can produce allergic reactions in some people.
Stinging isn't the only problem. The ants are altering ecosystems, reducing native ant species in infested areas, as well as increasing pests such as aphids and scales.
And there's more.
Some ants are natural seed dispersers. They carry seeds to their nest, remove a fatty portion to feed to their young, and discard the still viable seeds.
University of Toronto researchers created artificial ecological communities inside dirt‑filled plastic swimming pools to study the effects of seed‑dispersing ants on plants.
Ants In Your Plants
The pools were planted with four species of spring wildflowers. Three were native species and one an invasive species. Each pool was then populated with colonies of European fire ants or native woodland ants.
The scientists discovered that native ants dispersed fewer seeds of all four plant species. Their pools grew mainly native plants.
The fire ants transported more seeds at a faster rate, which apparently gave the invasive species the upper hand. Their pools were overrun by the invasive plants.
Invasive ant species are becoming more abundant in eastern North America. It appears they are not only responsible for reducing native ant populations and increasing pest numbers, they may be helping the spread of an invasive plant species. It's a one‑two punch for native ecosystems.
"Mutualism Between Co‑introduced Species Facilitates Invasion and Alters Plant Community Structure" (Royal Society)