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Hallie Pickhardt (301) 734-5175
Jerry Redding (202) 720-6959

USDA RESEARCHERS LOOK TO CITRIC ACID TO MANAGE INVASIVE COQUI FROGS

WASHINGTON, Sept. 16, 2002—In an effort to manage burgeoning populations of invasive coqui frogs in Hawaii, researchers with the U.S. Department of Agriculture's Animal and Plant Health Inspection Service are evaluating the effectiveness of citric acid, a common food additive.

Laboratory tests by researchers at APHIS' National Wildlife Research Center's Hilo, Hawaii, field station found that citric acid is an effective yet inexpensive pesticide for controlling the coqui frog. Based on these findings, APHIS will begin field tests to develop application methods that maximize the effectiveness of citric acid while minimizing any risk to the environment.

Citric acid, a natural product, is already on the Environmental Protection Agency's list of non-regulated, minimum risk pesticides. This means the EPA believes that no significant adverse effects to humans or the environment are associated with the proper use of citric acid as a pesticide.

Citric acid provides one more option for managing the coqui frog. Caffeine has already been found to be effective. APHIS scientists, however, are continually searching for more economical methods to selectively target this invasive species without impacting other species or residents.

The coqui frog, native to Puerto Rico, is known for its loud nighttime chirping. The noise from a group of frogs can exceed 90 decibels, equaling the intensity of a lawnmower. Likely transported to Hawaii on imported plant material in 1988, the coqui frog can now be found on Maui, Oahu and Kauai, as well as the main island where frog populations are firmly established in numerous locations.

The coqui is a threat to the islands' fragile native ecosystems. With its voracious appetite, the coqui frog has the potential to out-compete native species, especially native birds, by eating insects and other arthropods. These problems will continue to increase if the coqui frog is able to further expand its range and population.

It is a goal of APHIS' National Wildlife Research Center to protect natural resources against the effects of invasive species. NWRC is the research arm of APHIS' wildlife services program. The center is a world leader in the effort to develop selective, effective and socially acceptable methods for resolving damage and reducing risks posed by wildlife.