Sandy Miller HaysAgricultural Research Service
September 11, 2012
This could be the biggest thing since the “Mothra versus Godzilla” match-up.
If you’ve never come up against the Formosan subterranean termite, count yourself lucky; to paraphrase an old car commercial, “This isn’t your father’s termite.”
For starters, according to the University of Florida’s Department of Entomology and Nematology, a single colony of Formosan subterranean termites (FST) may contain several million termites, as opposed to several hundred thousand in a colony of our typical native subterranean termite species.
It’s called “Formosan” because it was first described in Taiwan in the early 1900s, but it probably hails originally from southern China. Known as the “super-termite” because of its incredibly destructive habits, it was apparently transported to Japan prior to the 1600s, and to Hawaii in the late 1800s.
It turned up in Texas, Louisiana and South Carolina in the 1960s, but as of 2010, it had spread to Alabama, California, Florida, Georgia, Mississippi, North Carolina and Tennessee. The hope is that it will be restricted to the southern United States because its eggs won’t hatch at temperatures below 68 degrees Fahrenheit.
In common with other termites, the FST feeds on wood and other materials that contain cellulose, such as paper and cardboard. But it’s also been known to chew through foam insulation boards, thin lead and copper sheeting, plaster, asphalt and some plastics! As you can imagine, this particular pest poses a major threat to structures (in other words, your house). It’s estimated that Formosan subterranean termites cause an estimated $1 billion annually in damages, repairs and control efforts.
So that’s the Godzilla of the insect world—a bug that can chew through lead sheeting.
Fortunately, just like in that great 1964 Japanese science fiction film “Mothra versus Godzilla,” we’ve got something we might be able to throw at Godzilla: a worm.
The scientists of the Agricultural Research Service (ARS) are among the world’s foremost authorities on microscopic wormlike organisms known as nematodes. These worms can be a force for good or for evil. Some species are parasitic, dependent on a host—a plant, an animal, an insect or even us humans—to survive. Others prowl through the soil and other hunting grounds for bacteria, fungi and other microbial prey.
The ARS scientists have special expertise in putting beneficial species of nematodes to work killing insects, as an alternative to using man-made pesticides. They’ve been busy identifying and describing nematodes that have potential as what are called “biological control agents” (non-chemical weapons) to combat the Formosan subterranean termite.
Since 1999, the scientists have identified seven nematode species that had been isolated from the cadavers of Formosan subterranean termites by another ARS scientist who’s since retired. Other specimens they’ve identified were collected from more exotic locales, including rural sites in Uzbekistan, where collaborators found species of Pelodera nematodes in the heads, abdomens or legs of sick or dead Turkestan termites.
The nematodes that have been used in the past to fight other insects aren’t efficient killers of the Formosan subterranean termites. That’s why the ARS scientists are seeking more virulent species of nematodes, along with symbiotic microorganisms such as bacteria that can assist in killing the termites.
The retired ARS scientist also found a nematode species called Poikilolaimus in Louisiana that might fit the bill. His experiments showed that this particular nematode species invades the heads of Formosan termites, and that a bacterial accomplice probably sickened the termites in the field.
The bacteria, which have been identified by an ARS microbiologist, are known to excrete trace amounts of cyanide, but the scientists haven’t yet determined whether that contributes to the termite’s death.
That teamwork between bacteria and nematodes raises an interesting prospect: using the worms to carry bacteria that can sicken the insects, rather than having the nematodes themselves do the dirty work of killing the insects, which has been the traditional approach. For example, the nematodes could be applied to the soil, and they would seek out, penetrate and then infest their unhappy insect hosts with lethal doses of entomopathogenic (the 25-cent word for “causing disease in insects”) bacteria.
Perhaps it’s not as epic a battle as Mothra taking on Godzilla … but if these worms can help stop these house-eating insects, that’s definitely what I’d call a happy ending!
The Agricultural Research Service is the chief in‑house scientific research agency of the U.S. Department of Agriculture. You can read more about ARS discoveries at http://www.ars.usda.gov/news.