Researchers find way to stop spread of frogs

Associated Press

HILO, Hawai'i — State researchers have developed a process that uses hot water to help control the burgeoning population of Caribbean tree frogs plaguing the Big Island.

The heat treatment will help ensure the tree frogs aren't being spread from state nurseries to remote areas where reforestation efforts are under way.

The process developed by researchers from the University of Hawai'i at Manoa, the University of Hawai'i at Hilo and the state Division of Forestry and Wildlife drenches plants and their pots in 113-degree water for three minutes. The plant is then cooled with water at a lower temperature.

The tree frogs have populated more than 100 areas on the Big Island, driving residents to distraction with their noisy chirping. Biologists fear the frogs will prey on native insects and spiders, spread plant diseases and increase rat and mongoose populations by serving as a food source. They have also been seen on O'ahu, Maui and Kaua'i.

The heat process kills any tree frogs present on the plant or its planting materials, but doesn't hurt the plant, said Marcel Tsang of the UHH College of Agriculture, Forestry and Natural Resource Management.

Plants are treated immediately before they are transported from state nurseries to reforestation sites, said Arnold Hara, a UH entomologist. Transporting tree frogs into previously non-infested areas is against state law.

A drenching system at the DFW facility in Hilo has been in operation for about a month. The process kills other pests in planting materials, including scales, nematodes, snails and root mealybugs, making it a potentially valuable process for nurseries that export plants from Hawai'i, said Tsang, who developed the process with Hara and Ed Brodie of the DFW.

"Most of the growers really take pains to ensure that the plants are clean, but you never know," Tsang said.

The state is awaiting federal approval of a plan to use a caffeine-based spray to kill tree frogs.