Ants at work
February 20, 2014
In the forests outside Lawrence, Kansas, a colony of ants was working hard this summer, and so was graduate student Kim Drager. We can see ants above ground. Their nests are visible as ant mounds. They move around carrying food back to their nests. But, what are those ants doing underground? And, how does their work affect the soils they live in?
Drager is graduate student earning her Masters’ degree at the University of Kansas. Her research is on a specific ant species, Formica subsericea. “Some of their colonies can last for decades,” says Drager. Her research focused on how the behavior and actions of this common ant affect the soil they live in.
F. subsericea is a large black ant native to the United States, and commonly found in fields and forests. They are carnivores, eating insects, either dead or alive. Drager also found seeds in the nests she studies, so their diets may have some variety.
Drager hypothesized that the work of the ants might be improving the soil. She looked at soil particle size, soil density and the total carbon content in the ant nests. The findings? “Ants may be better housekeepers than we thought,” says Drager. The nests were very clean inside, and there was no difference in soil carbon inside the nest versus outside.
With regard to soil density, “the mound has a lower density than the rest of the nest, so maybe they are not doing any backfilling,” says Drager.
Building nests to accommodate their growing numbers is a full time job for some of the ants. The queen lives in luxury inside a large chamber. Worker ants and drones do most of the labor. As the colony grows, workers make new tunnels that connect to larger chambers, where food can be stored or eggs can await hatching.
Though the F. subsericea in Kansas may not be adding to total soil carbon, they do provide aeration of the soil. And, although they are considered a pest if the nests are too close to our homes, F. subsericea is perfectly happy to stay outside our homes. We just need to make sure to deter them by not planting aphid-attracting plants, caulking well, and other discouraging behaviors. Then, we can live peacefully with our tidy friends, and they can continue to do their service to humankind.