Author
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Wiltz, Beverly |
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Submitted to: Ph D Dissertation
Publication Type: Other Publication Acceptance Date: 8/1/2005 Publication Date: 8/1/2005 Citation: Wiltz, B.A. 2005. Applied Ecology and Control of Imported Fire Ants and Argentine Ants. University of Georgia. Ph.D. Dissertation 202 pp. 2005.ssertation Interpretive Summary: The red imported fire ant, Solenopsis invicta Buren, and Argentine ant, Linepithema humile (Mayr), are invasive species that are major pests in urban, natural, and agricultural habitats. This dissertation contains a series of studies with the goal of identifying ways to use the biology and ecology of imported fire ants and Argentine ants to develop more targeted methods of controlling these pests, using both traditional insecticides and alternative methods. In an evaluation of pesticide properties against the two ant species, bifenthrin had properties best suited for use as barrier or mound treatments. It was the fastest acting of the toxicants tested and was the only insecticide that acted as a barrier to ant movement. Fipronil had high horizontal toxicity and delayed topical toxicity, properties that are desirable in a broadcast treatment. Chlorfenapyr and thiamethoxam were best suited to use as mound treatments, as they had low horizontal toxicity and did not impede ant movement in barrier tests. Basil, citronella, lemon, peppermint, and tea tree essential oils deterred Argentine ants and red imported fire ants from crossing treated surfaces. In continuous exposure tests, citronella oil was toxic to both Argentine ants and fire ants, and peppermint and tea tree oils demonstrated mild toxicity to Argentine ants. These essential oils provide an alternative treatment method for situations where the use of deterrent or toxic natural products is preferred over contact insecticides. Additionally, these oils may be used in conjunction with other methods to provide additional protection. Triolen, a component of the red imported fire ant brood recognition pheromone enhanced removal of treated granules by S. invicta workers. At a rate of 0.06% fipronil plus triolein, there was 90.5% mortality in laboratory colonies, versus 46.5% with the same rate of fipronil without triolein. This technique has potential to provide a more species specific ant control method and to alleviate the problem of variable food preferences that sometimes makes control of some species by baiting difficult. Ground surveys conducted at two sites in northeastern MS provide the first description of imported fire ant distribution within blackland prairie habitats. Mean fire ant mound densities were 53.6 and 54.5 mounds / ha at the two sites. Mounds tended to be smaller in more disturbed habitats. Imported fire ants were found in open areas, with the highest infestation rates in disturbed habitats and no fire ant mounds being found in forest habitats or prairie containing a large proportion of mature trees. Infested and unifested plots did not differ in proximity to disturbed habitats. In addition to contributing to our knowledge of imported fire ant distribution in natural habitats, the results of this study have practical implications for habitat conservation and restoration. With this new information about which habitats within blackland prairies have been invaded by imported fire ants, restoration groups can target these specific areas for fire ant control and native arthropod conservation. Technical Abstract: The red imported fire ant, Solenopsis invicta Buren, and Argentine ant, Linepithema humile (Mayr), are invasive species that are major pests in urban, natural, and agricultural habitats. The goal of this dissertation was to study aspects the chemical sensitivity, behavior, and ecology of each species to enhance control options. In these studies, I: 1) provide recommendations for the optimal usage of various insecticides against each species, 2) evaluate deterrent and toxic effects of natural products, 3) develop a delivery system for ant toxicants that uses a pheromonal attractant to facilitate toxicant transfer by contact, and 4) determine which habitats within blackland prairies are most susceptible to invasion by imported fire ants. In laboratory studies to determine effects of several insecticides, bifenthrin had properties best suited for use as barrier or mound treatments against both species. It was the fastest acting of the chemicals tested and was the only chemical that acted as a barrier to ant movement. Fipronil exhibited high horizontal toxicity and delayed topical toxicity, properties that are desirable in a broadcast treatment. Chlorfenapyr and thiamethoxam appeared best suited to use as mound treatments, as they had low horizontal toxicity and did not impede ant movement in barrier tests. At least one of the four tested rates of basil, citronella, lemon, peppermint, and tea tree oils were repellent to both ant species. In continuous exposure assays, citronella oil was toxic to both species, and peppermint and tea tree oils were toxic to Argentine ants. Of the semiochemicals tested, only triolen, a component of the red imported fire ant brood recognition pheromone, enhanced removal of treated granules by S. invicta workers. At a rate of 0.06% fipronil plus triolein, there was 90.5% mortality in laboratory colonies versus 46.5% with the same rate of fipronil without triolein. Ground surveys and analysis of remotely sensed images were conducted for two sites in northeastern Mississippi, both of which contain S. invicta x S. richteri hybrid imported fire ants. Mound densities were highest and individual mounds were smallest in disturbed areas. Fire ants were not found in forest or chalk outcrop plots or in prairie containing > 26% tree cover. |
