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United States Department of Agriculture

Agricultural Research Service

Research Project: POSTHARVEST TREATMENT OF TROPICAL COMMODITIES FOR QUARANTINE SECURITY, QUALITY MAINTENANCE, AND VALUE ENHANCEMENT Title: Field Control of the Invasive Ant Wasmannia auropunctata (Hymenoptera: Formicidae) in a Tropical Fruit Orchard in Hawaii

Authors
item Souza, Evann - UH - HILO
item Follett, Peter
item Price, Don - UH - HILO
item Stacy, Elizabeth - UH - HILO

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 5, 2008
Publication Date: August 1, 2008
Citation: Souza, E., Follett, P.A., Price, D., Stacy, E. 2008. Field Control of the Invasive Ant Wasmannia auropunctata (Hymenoptera: Formicidae) in a Tropical Fruit Orchard in Hawaii. J. Econ. Entomol. 101:1068-1074.

Interpretive Summary: The little fire ant (LFA), Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae) is an invasive ant that forms supercolonies when it successfully invades new areas. Since its introduction in 1999, LFA has invaded many agricultural sites. Amdro (hydramethylnon; in bait stations), Esteem (pyriproxyfen; broadcast bait), and Conserve (spinosad; ground spray) were tested for their efficacy against LFA in a rambutan and mangosteen orchard by making biweekly treatments for 16 weeks. The Amdro and Esteem treatments showed a 60-90% reduction in ant numbers. No plots for any of the treatments achieved 100% reduction. Many LFA were found nesting in protected sites in the orchard trees which may have compromised the ground-based control methods. Density estimates from the orchard floor indicated the LFA supercolony may exceed 95 million ants per acre.

Technical Abstract: The little fire ant (LFA), Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae) is an invasive ant that forms supercolonies when it successfully invades new areas. LFA was first reported in Hawaii in 1999 and has since invaded a variety of agricultural sites including nurseries, tropical fruit farms, macadamia orchards, and pastures. Amdro (hydramethylnon; in bait stations), Esteem (pyriproxyfen; broadcast bait), and Conserve (spinosad; ground spray) were tested for their efficacy against LFA in a rambutan and mangosteen orchard by making biweekly treatments for 16 weeks. Amdro and Esteem treatments showed a significant reduction in LFA on weeks 12 and 16 compared with untreated control treatments. On week 12, LFA were significantly higher in the Conserve treatment than the Amdro and Esteem treatments, but significantly lower than the untreated control treatments. No plots for any of the treatments achieved 100% reduction. Homoptera on branch terminals were significantly lower in the Amdro and Esteem treatment on week 16. Many LFA were found nesting in protected sites in the orchard trees which may have compromised the ground-based control methods. Absolute density estimates from shallow core samples taken from the orchard floor indicated the LFA supercolony exceeded 95 million ants per acre.

Last Modified: 10/25/2014
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