New Bait May Prove to Be Fatal Last Meal For Pest Termite

By Jan Suszkiw
October 12, 1999

NEW ORLEANS, Oct. 12--An experimental bait that tempts the termite's taste buds with plant fiber and other ingredients is earning high marks--but not just from the insect. U.S. Department of Agriculture scientists are pleased with early test results showing the bait is quickly attacked by the termite and can require less pesticide to kill the wood-eating pest.

In laboratory trials, the bait required up to 95 percent less toxin than other bait products to kill off captive termite colonies, report Guadalupe Rojas and Juan Morales-Ramos, entomologists with USDA's Agricultural Research Service in New Orleans. The agency has applied for patent protection on the bait, primarily designed for the Formosan subterranean termite, Coptotermes formosanus. In tests, the bait often stimulatedfeeding within two weeks of deployment. By six weeks, the termite population declined, and by three months little or no activity was evident.

Native to southern China and nearby Pacific islands, the Formosan subterranean termite was discovered in the southern U.S. during the mid-1960s at several seaport cities, including New Orleans. Possibly transported there by ships returning from World War II’s South Pacific theater, the termite today is established in nine southern states, California and Hawaii. In the U.S. alone, the exotic pest costs an estimated $1 billion dollars annually in damage, repairs and control expenses

The scientists' research is part of a USDA-led national campaign called Operation Full Stop, begun last year to reign in the Formosan termite and minimize its damage. Conventional control methods call for applying chemical insecticides along a building’s perimeter. However, such defenses often fail to stop the Formosan termite. That has forced pest control experts to take the offensive. A key attack strategy is to deploy toxic baits to eliminate the termite population.

"The trick is making sure the termites quickly find and readily feed on the bait, along with the impregnated toxins," says Rojas, who is with the ARS' Southern Regional Research Center in New Orleans. Moreover, she adds, the toxin must be slow-acting and not kill the termites too soon. That’s because the pests need time to distribute the toxin to other colony members by exchanging food or secretions, such as through grooming, excretion or regurgitation.

With that in mind, the two researchers developed an entirely new bait formula. To do this, they carefully studied the termite's foraging behavior, feeding preferences, and nutritional needs for growth and reproduction. Early on, they looked to nature for clues. In decaying wood, for example, they found natural substances that foraging termites readily consume and carry to their queen to help with her egg-laying.

After identifying the substances, the researchers combined them into feeding stimulants. They then mixed the stimulants with ground plant fiber, water and other ingredients that maintain proper texture and moisture. They also designed a covering for the bait (called a “matrix”) that maintains an environment the termites prefer.

Standard baits employ wooden stakes and cardboard or paper as carriers for the toxins. But the new bait’s “ingredients” stimulate the termites to feed--and come back for more. This results in more toxin getting spread quickly to more colony members, says Rojas, at the ARS' center's Formosan Subterranean Termite Research Unit.

In lab trials there, the bait required less pesticide than standard products and triggered quicker termite feeding. By six weeks, such feeding had killed off much of the colony. The scientists used both experimental and commercially registered pesticides, including diflubenzuron and hexaflumuron. Both these chemicals disrupt the formation of chitin, a substance comprising the termite's outer "skin," gut wall and air tubes.

Field studies conducted at New Orleans City Park confirmed the scientists’ lab findings. In the study, they installed yellow pine stakes next to the ARS bait matrix. A few weeks later, they checked for termite feeding damage. The results showed that the termites were nine times more likely to attack and eat the baits than the pine stakes. This summer, licensed pest control operators in New Orleans began monitoring seven homes in which the ARS bait matrix had been installed. Similar trials are also underway in Florida, Mississippi and Alabama.

Rojas says the baits, which contained diflubenzuron, were installed in seven New Orleans homes last June. Biweekly inspections revealed termite feeding on the baits as soon as two weeks after their installation. Once that happened, termite activity declined in about six weeks, mirroring findings in the lab. The ARS research center where Rojas and Morales work will also install the bait in several of its buildings as well as around infested trees on the facility’s property. Like many buildings and trees in the Greater New Orleans area, the ARS center also has been invaded by the Formosan termite.

Scientific contact: Guadalupe Rojas and Juan Morales-Ramos, Formosan Subterranean Termite Research Unit, ARS Southern Regional Research Center, New Orleans, La., phone (504) 286- 4382, fax (504) 286-4419, grojas@nola.srrc.usda.gov, jmorales@nola.srrc.usda.gov.