Fungal Foam Targets Termites Inside Trees

A fungus-filled foam is being tested as a biological alternative to using chemicals to kill termites hiding inside tree trunks and other hard-to-reach places.

Developed by Agricultural Research Service (ARS) scientists in Peoria, Ill., and New Orleans, La., the foam contains spores of the fungus Paecilomyces fumosoroseus, which kills termites by feeding and growing inside their bodies.

Since the fungus poses no such danger to people and nonhost insects, it's an appealing alternative to chemically treating termite-infested trees with insecticides, notes Chris Dunlap. He's a chemist with ARS' National Center for Agricultural Utilization Research in Peoria.

Dunlap codeveloped the foam with microbiologists Mark Jackson—also at the Peoria center—and Maureen Wright, with ARS' Southern Regional Research Center in New Orleans.

A top target of theirs is the Formosan subterranean termite, Coptotermes formosanus. A nonindigenous species that's become established in the southern and southwestern United States, the Formosan termite is unrivaled in the size of its colonies, tunneling and appetite for cellulose in wood materials and living trees.

In New Orleans alone, the pest costs an estimated $300 million annually in damages and losses. But if the team's tests in New Orleans' City Park are any indication, the fungal foam could make the heartwood of live oaks and other host trees far less hospitable to Formosan termites.

Indeed, researchers have observed little to no termite activity in trees originally treated with the fungal foam in 2005. However, because some control trees were lost to Hurricane Katrina in August 2005, additional tests were begun in the spring of 2007 to further substantiate the foam's effectiveness.

When injected into trees, the foam expands into any cavities or tunnels the pests have made in the heartwood. Upon collapsing, it disperses spores onto the termites, or to areas where the termites travel.

You can learn more details by reading a longer article in this month's issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research agency.