Termites Weaken Trees

Most termites don’t kill trees, but Asian subterranean termites are slaying some pine trees in south Florida and damaging the rest of the local urban tree canopy, a University of Florida study found.

“Our beloved native slash pine is lethally stressed by this termite, which is unexpected,” said Thomas Chouvenc, a UF/IFAS assistant professor of urban entomology and faculty member at the Fort Lauderdale Research and Education Center. Not only can these invasive termites kill pine trees, they also hollow out the trunks of many other trees, including oaks, making them structurally fragile and susceptible to hurricanes.

Chouvenc led a 2018 published study that shows the extent of damage wrought by Asian subterranean termites in two suburban, residential areas of Broward County, Fla. For the study, published in the journal Florida Entomologist, Chouvenc walked neighborhoods to assess more than 400 slash pines in two residential areas of Fort Lauderdale and in city parks.

UF/IFAS

The city lost 12 percent of its pine trees in just a few years, and more than 50 percent of the pine trees surveyed are currently infested by this termite, Chouvenc said. He also noted that the termites hollowed out some large oak trees that eventually collapsed during Hurricane Irma in 2017.

“Our results suggest Asian subterranean termites have the potential to kill pine trees and severely damage oak trees in the urban canopy,” said Chouvenc. The termite damage in pine trees is unique and never observed before, as the damage acts as a girdle to the trees, killing them slowly, researchers said. Chouvenc said he and his colleagues want to raise major concerns about the fate of weakened trees if a strong hurricane hits south Florida.

Since Hurricane Wilma in 2005, many trees sustained major damage from the Asian subterranean termites, Chouvenc said. As Irma struck Florida in September 2017, the center of the storm spared Broward County, and most oak trees lost only a few branches. Still, in his survey, Chouvenc found that Asian subterranean termites had hollowed all three of the oak trees he examined. Those trees collapsed during hurricane Irma and damaged properties. Chouvenc believes that could be a bad omen, as many other trees are being weakened with current termite infestation and a direct hit by a future hurricane would amplify the potential damage.

“The rate of infestation in pine and other types of trees by this termite may be critical in the near future for the overall survival of a diverse urban tree canopy which is in the process of being irreversibly altered,” he said. — Brad Buck, University of Florida Institute of Food and Agricultural Sciences