Termite terminator

An LSU AgCenter researcher has a novel approach to stopping the advance of termite colonies.

BY RICK BOGREN

Likening her creation to a "Trojan horse," an LSU AgCenter researcher has developed a bacteria shuttle capable of introducing and spreading a "killer gene" into a termite colony. Now, she's looking for the killer.

Although termites feed on wood and other cellulose products, they depend on bacteria in their digestive tracts, or gut, to actually digest the wood fibers so they can get the nutrients they need.

Dr. Claudia Husseneder, an entomologist at the AgCenter, has come up with a way of transferring genetically modified bacteria into termite populations. She's looking for a killer bacterium to put the kibosh on the Formosan subterranean termite colonies that are eating their way through Louisiana cities.

Believed to have entered Louisiana and other Southern coastal states in wooden crates returned from the Pacific Rim during and after World War II, the insects have steadily increased in number and destructiveness over the past 55 years. Scientists first discovered the Formosan subterranean termites in the 1960s in Southern port cities, including New Orleans and Lake Charles.

Since then, the termites have moved steadily north in Louisiana and have been found in all parishes south of I-10 and I-12, as well as in some areas of north Louisiana. Experts estimate they're responsible for $1 billion in damage each year in the United States and as much as $300 million a year in New Orleans alone.

"To help understand what's going on, we need to understand the biology of termites and their gut flora," says Husseneder. "It provides information to approach control better."

What Husseneder wants to do is engineer bacteria found exclusively in the termites' gut to produce substances that would be toxic only to Formosan subterranean termites, which don't have natural enemies in the United States. She says one advantage of using bacteria is that they naturally multiply and don't dilute like chemicals as they're passed around a colony.

"Each worker termite has a stable microbial community in its gut, which is naturally exchanged between colony members through social interactions, such as grooming and feeding each other," Husseneder says. "Therefore, we felt that natural gut microbes would be excellent tools for termite control."

Using what she terms a "bacteria shuttle system," Husseneder is using microbes as tools and targets for termite control. Her initial work was done with bacteria isolated from the termite gut and engineered to produce flourescent protein, which causes bacteria to glow under ultraviolet light, to see if the process would work. And it does.

Husseneder's laboratory work has shown that termites can be easily infected by feeding them with the engineered bacteria. "They're able to survive in the termite gut and are rapidly transferred among colony members," she says. "Even a few termites infected with 'glowing' bacteria can infect a whole laboratory colony within one week."

In collaboration with other entomologists and scientists from the Department of Veterinary Sciences, Husseneder has identified proteins that destroy the three species of protozoa on which the termites depend for digesting wood. "We are now in the process of measuring the activity of these protozoa-killing proteins by injecting them directly into the termite hindguts," she says.

The next step is to genetically engineer termite-gut bacteria to produce efficient, termite-killing proteins. "To reduce the risk of environmental contamination, we will use specific bacteria that are not able to survive outside the termite gut as our shuttles," Husseneder says. "Ultimately, we hope to develop a self-replicating, self-perpetuating product that will kill termites rapidly plus be cost-effective and target-specific."