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Battling Exotic Ant Pests in American Samoa

Nifa Author
Margaret Lawrence, Writer-Editor

Invasive species pose a threat across the United States and its territories, but they can be especially challenging for the U.S. South Pacific territory of American Samoa. Among the invasive pests menacing the territory are several non-native fire ant species. 

The tropical fire ant (Solenopsis geminata) invaded American Samoa in the early 2000s and is known for its painful stings. However, a new non-native fire ant species could become an even more serious pest.  

The little fire ant (Wasmannia auropunctata) was first detected in the territory in late 2018. Researchers indicate it could disrupt ecosystems across American Samoa. Like the tropical fire ant, the little fire ant stings—and is a problem for people, pets and livestock. Additionally, its ability to forage and nest in a variety of areas could make agricultural production and even daily life difficult.  

Strengthening American Samoa's ability to prevent, detect and respond to invasive exotic ants is essential to preserving the territory's agricultural production, its environment and its people's unique way of life. Thanks to funding from USDA’s National Institute of Food and Agriculture (NIFA), a team at American Samoa Community College is leading an effort to bolster protection for native ecosystems by enhancing the territory's capacity to detect and respond to invasive ant incursions. 

The project’s primary goal is to improve local capacity to detect and respond to little fire ant and other ant invaders. Within the first two years of a five-year project, the American Samoa Community College team has already made important advances. 

At the six sites where little fire ants have been found, control measures at five of them have reduced little fire ant prevalence to zero. Surveys are underway at three newly detected infestations using the methods developed in this project. The team will continue to monitor all the sites for at least three years and resume treatment programs if any remnant populations are found. 

The project team plans further surveys to detect and map infestations of little fire ants in the territory as well as continue to assess the effectiveness of different pesticides and other management practices measures for controlling little fire ants. 

Additional Impacts 

  • Catalogued ant species and updated a reference collection to help identify new invasive ant species invaders. 

  • Developed and implemented efficient methods to survey and detect of exotic ants. 

  • Improved public awareness of the threat of exotic ants and how to report new infestations which led to the discovery of additional little fire ant infestations. 

  • Demonstrated that control methods developed by the University of Hawaii work against the little fire ant in American Samoa. 

  • Got approval from U.S. Environmental Protection Agency for use in American Samoa of effective insecticidal bait products. 

This NIFA-supported effort has made possible the implementation of an effective little fire ant control program. Additionally, this control program could help guide responses to future incursions of other invasive pest ant species in American Samoa.  

Top image: Eli Sarnat, PIAkey: Invasive Ants of the Pacific Islands, USDA APHIS PPQ, Bugwood.org.

Farm Bill Priority Areas
Bioenergy, natural resources, and environment
U.S. States and Territories
American Samoa
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