Combo Control

Scott Bauer, USDA Agricultural Research Service, Bugwood.org

Editor’s Note: This article originally appeared in Entomology Today, a project of the Entomological Society of America with the goal of reporting interesting discoveries in the world of insect science and news from various entomological societies. To learn more, visit www.entomologytoday.org.

A new termite control method, which was developed in recent years, looks to combine the advantages of a liquid application with the comprehensive impact of existing baits. Nan-Yao Su, Ph.D., distinguished professor of entomology at the University of Florida, and colleagues have been working on a fluid termite bait since 2011 as the next evolution of the termite bait methods that Su first developed in the 1990s. In June, Su and colleagues shared results of a long-term field test of fluid termite bait in a report published in the Journal of Economic Entomology.

The fluid bait formulation was a mixture of 10 percent dry bait substance impregnated with hexaflumuron (a chemical that interferes with termite growth, specifically inhibiting synthesis of chitin in the termite’s exoskeleton) and 90 percent fluid cellulose solution. The researchers tested the fluid bait in three trees and three buildings with infestations of Formosan subterranean termites (Coptotermes formosanus). They drilled half-inch diameter holes in affected wood and used a caulking gun to inject the fluid bait into the tree or wall interiors. Then they monitored the termites’ reaction and the effects on the infestations.

Gerald J. Lenhard, Louisiana State University, Bugwood.org

In all of the test cases, the termite colonies were eventually eliminated. But they varied in the amount of time and bait reapplications needed. One colony was eliminated in four months, while the longest took 22 months. Some tests took just one bait application, while others took as many as 10 or 11. The researchers posit that disturbance caused by drilling and injection caused some of the delayed results, as foraging termites were chased away for a few months before they returned. The varying size of the termite colonies — and thus their alternative foraging options — also could have played a role in the variability.

Su says the results of the study are encouraging and that he hopes the fluid termite bait product could be available to pest management professionals in the not-too-distant future. “We need to do more field trials to make sure we encounter most of the problems we will encounter and solve them first,” he says.

Hexaflumuron is classified by the U.S. Environmental Protection Agency as a “reduced-risk pesticide,” meaning it poses less risk to people and the environment than alternatives. Su cites this as an additional potential advantage of the prospective fluid bait system.

“Termite baits use less-toxic insecticides at smaller quantities than liquid termiticides, hence they have much less environmental impact,” he says. “Yet, more than 50 percent of the termite control today still relies on old liquid termiticide barriers that cannot eliminate termite colonies, and even those that use baits still inject liquid termiticide into active galleries. There are many reasons for this, I am sure, but I hope the introduction of fluid bait will encourage the industry to make the switch, even by just a little.”