Erythritol, a low-calorie sugar substitute, has been found to exhibit slow toxicity to the red imported fire ant (Solenopsis invicta), raising the possibility of its use as an environmentally friendly bait for management of the invasive species. (Photo credit: April Noble, Antweb.org, Bugwood.org)

By Josh Lancette

Researchers from China have discovered that some sweeteners can be lethal to the red imported fire ant (Solenopsis invicta), a devastating pest found South America, the United States, Australia, Asia, and on many Caribbean islands. In a test, ants that were fed erythritol, aspartame, and saccharin had a mortality rate higher than 80 percent. This finding could lead to the use of baits formulated out of sweeteners, which could be an environmentally friendly alternative to using insecticides to control the ant.

Josh Lancette

In their report, published in March in the Journal of Economic Entomology, the researchers suggest that erythritol, in particular, shows potential, as it fulfilled an important requirement of baits.

“Erythritol exhibited slow toxicity in the fire ants, which is helpful for achieving transmission among an entire colony,” said Yijuan Xu, one of the researchers.

In other words, it takes a while for the ants to die, meaning the ants that pick it up can bring it back to the colony for other ants to feed on, thus increasing the reach of the poison. This finding is important because baits can be tricky to perfect. They need to be palatable to the ant, they can’t be repellent, they need to be able to be moved by the ant, they need to be slow-acting so that the ant has time to bring the bait back to the colony, and they need to be lethal to the ant and ideally inaccessible to other insects. If any of those criteria aren’t met, the bait likely will be ineffective. Meeting the slow-acting requirement is a necessary first step for a product to be formulated into a bait.

However, it is just a first step. More studies are needed before it can be determined if sweeteners can be effective in baits.

“Determination of the degree of toxicity of artificial sweeteners, such as aspartame and saccharin, to fire ant colonies will require further evaluation,” the researchers write. “Additionally, all of the experiments were conducted in the laboratory; therefore, it will be necessary to test the effects of erythritol in the field and to determine the preference behavior of fire ants in relation to erythritol.”

Josh Lancette is manager of publications at the Entomological Society of America.