Citric acid Citric acid recently has emerged as a promising tool to control noisy coqui frogs in Hawaii, according to the U.S. Department of Agriculture.
a possible tool
in coqui fight
Lab tests find the common food
additive is an effective pesticideBy Diana Leone
dleone@starbulletin.com
The common food additive is a natural product and would not need the extensive safety precautions required of researchers testing caffeine's effects on people and other "non-target" creatures that might come in contact with it, a recent USDA release said.
FILE PHOTO With caffeine at least temporarily on the back burner for coqui frog control here, research on other ways continues.
The USDA learned last week it must wait at least until November before it begins test spraying of caffeine to eliminate the tiny, screeching frogs.
"We're at the beginning of the issue," said Earl Campbell, U.S. Fish & Wildlife Service invasive species manager.
Though Campbell was one of the first to discover that a caffeine solution would kill coqui frogs, he's not attached to the method, he said.
Laboratory tests by USDA researchers in Hilo "found that citric acid is an effective yet inexpensive pesticide for controlling the coqui frog," the agency said. Researchers plan to do field tests on how best to use it.
Maui Invasive Species Coordinator Jack Peterson said preliminary results from three caffeine field tests on that island in the past month show it's "very effective at killing frogs," and doesn't seem to have problematic side effects.
However, he said, if a substance like citric acid, found in citrus fruits such as lemons, works as well, it could "be the product of choice. ... It is our hope to have a really safe, effective tool."
Other potential coqui-fighting methods include:
>> Spraying areas with hydrated lime, which kills the frogs. The lime is readily available as a soil enhancer.Once a month, the various experimenters gather to compare notes as the Coqui Frog Working Group.>> Removing vegetation that coquis favor from around buildings.
>> Trapping the frogs.
There also are several techniques under consideration to de-frog potted plants, which is how the animals travel from island to island:
>> Zapping the plants with electricity.
>> Drenching the plants, briefly with hot water.
>> Putting the plants in a refrigerated holding area for a limited time.
>> Vapor-heating plants in the same machines used to prepare papayas for export.
>> Placing cinders in pot drainholes to discourage frogs from hiding there.
The group brought New York-based coqui expert Larry Woolbright to the Big Island in August to help them out.
Woolbright, a biology professor at Siena College in Albany, N.Y., calls the question of whether to eradicate the coqui in Hawaii "a complex issue.
"I do think they're very neat critters. They're behavior is fascinating, their adaptation is fascinating. But on the other hand, I understand they don't belong in Hawaii."
State of Hawaii
Environmental Protection Agency
Fish and Wildlife Service
