When just a few termites take the bait, it kills the whole colony

Less is more when it comes to just how many subterranean termites have to eat a chemical known as a chitin synthesis inhibitor before the entire colony is eliminated, a study of 1.68 million termites shows.

For the study, which appears in the Journal of Pest Science, researchers took a closer look at how much bait it takes to eliminate a subterranean colony.

As a prominent industry standard used in bait systems, chitin synthesis inhibitor (CSI) baits were first commercially used in the mid-1990s. Bait systems work as slow-acting agents. Current commercial formulations can provide a cost-effective and sustainable solution against potential damage from subterranean termites.

“If termites feed on the bait, it can lead to colony elimination in a few months, as University of Florida researchers have demonstrated in the past three decades through dozens of keystone studies,” says Thomas Chouvenc, an assistant professor of urban entomology at the University of Florida/Institute of Food and Agricultural Sciences Fort Lauderdale Research and Education Center (REC).

“One of the remaining questions we had was, how many termites feeding on the bait does it take to reach colony elimination?” says Johnalyn Gordon, who recently graduated from UF/IFAS with a master’s degree.

“If the termites feed on the bait, they are already dead, but they don’t know it yet.”

“From a previous study in our lab, we knew that it only takes a day of termites feeding on bait to reach a colony-wide lethal dose, but how many termites within the colony need to actively feed on the bait remained unclear,” says Joseph Velenovsky, a doctoral candidate at UF/IFAS Fort Lauderdale REC.

The students, under the supervision of Chouvenc, worked with 1.68 million termites at the Fort Lauderdale REC to answer this question.

“They used 27 large colonies of termites that the team spent four years rearing in the lab, with approximately 62,500 termites in each of them,” says Chouvenc.

“It was quite a task to accomplish to show that food sharing behaviors of the bait were happening at the termite colony level, from just a fraction of foragers,” Chouvenc says.

The graduate students’ efforts paid off. They determined that it takes less than 5% of the entire termite population of a colony feeding on a bait station for a short duration to reach colony elimination.

More critically, they showed that it only takes 77 milligrams of a termite-specific pesticide to eliminate one million termites, confirming that CSI baits remain the most environmentally-friendly control technology available.

“It was remarkable to observe that only a small portion of foragers feeding on bait was sufficient to kill the colonies,” Velenovsky says.

“Even more remarkable, if a small number of workers feed on a tiny amount of bait for just a few days, the colony has already reached a ‘point of no return’ and is doomed to be eliminated within 90 days,” Gordon says.

Even if subterranean termites can be seen in baits stations for up to three months, the colony is technically already in the process of dying within the first week, even after a small number of termites feed on it, the researchers discovered.

“If the termites feed on the bait, they are already dead, but they don’t know it yet,” Gordon concludes.

Source: University of Florida

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