To escape a watery death, the insects construct relatively sophisticated structures on the fly
The threat of death is no obstacle for some hungry fire ants. To escape drowning while feeding on sugary water, black imported fire ants built syphons out of sand that moved the water to a safer spot.In the wild, black imported fire ants (Solenopsis richteri) typically eat honeydew produced by aphids. In the lab, entomologist Jian Chen of the U.S. Department of Agriculture’s Agricultural Research Service in Stoneville, Miss., and colleagues provided the ants with containers of sugary water. The insects have a hard, water-repellent outer covering called a cuticle, and can typically float on a liquid — and sure enough, the insects floated and fed without a problem.
The researchers then reduced the water’s surface tension with a surfactant to make it more difficult for the ants to float. While some ants drowned, most stopped entering the containers and instead used grains of sand placed nearby to build structures leading from the inside of a container to outside of it. Those structures acted like syphons. Within five minutes of building one, nearly half of the water was drawn out through the sand pathway, allowing the ants to feed safely.
“The fact that ants are building little syphons is new and interesting,” says Valerie Banschbach of Gustavus Adolphus College in Saint Peter, Minn., who was not involved in the study. The insects’ “flexibility to act in a creative way responding to a situation suggests that they have higher cognitive abilities than what is traditionally believed.”
