APPLIED ECOLOGY AND CONTROL OF IMPORTED FIRE ANTS AND ARGENTINE ANTS (HYMENOPTERA: FORMICIDAE) by BEVERLY ANNE WILTZ (Under the Direction of Daniel R. Suiter) 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. Bifenthrin had properties best suited for use as barrier or mound treatments against both species. In laboratory assays, 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. INDEX WORDS: Solenopsis spp., Imported fire ant, Linepithema humile, Argentine ant, Chemical control, Repellant, Attractant, Pheromone, Remote sensing, Landscape ecology APPLIED ECOLOGY AND CONTROL OF IMPORTED FIRE ANTS AND ARGENTINE ANTS (HYMENOPTERA: FORMICIDAE) by BEVERLY ANNE WILTZ B.S., LOUISIANA STATE UNIVERSITY, 1992 M.S., LOUISIANA STATE UNIVERSITY, 1996 A Dissertation Submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY ATHENS, GEORGIA 2005 © 2005 Beverly Anne Wiltz All Rights Reserved APPLIED ECOLOGY AND CONTROL OF IMPORTED FIRE ANTS AND ARGENTINE ANTS (HYMENOPTERA: FORMICIDAE) by BEVERLY ANNE WILTZ Major Professor: Daniel R. Suiter Committee: Wayne A. Gardner C. Wayne Berisford Electronic Version Approved: Maureen Grasso Dean of the Graduate School The University of Georgia August 2005 DEDICATION This dissertation is dedicated to my parents, Paul and Rebecca Wiltz, and my grandmother, Sarah Mooney, for their love, prayers, and encouragement throughout this process. iv ACKNOWLEDGEMENTS I thank my major advisor, Dan Suiter, for his guidance and support throughout my Ph.D. studies. I am grateful to my committee member Wayne Gardner for his insight and critical reviews of my work and for keeping me informed of the latest developments in the lives of Tony Soprano and Family. My other committee member, Wayne Berisford, provided valuable assistance developing the methodology for work included here and preliminary attempts to isolate potential ant attractants. My work on fire ant landscape ecology would not have been possible without the collaboration of J. T. Vogt of the USDA-ARS in Stoneville, MS. I thank him for his assistance with the field survey, providing the imagery used for land cover classification, and his friendship. Juang “J. C.” Chong has been there for me through good and bad times, has been a willing accomplice any time I feel the need to get away, and made sure I have always eaten well, even when I have become too absorbed in my work to take care of myself. My sister, Kathleen Wiltz, has accompanied me on many adventures and has never let me forget the importance of having big dreams and doing whatever it takes to make them come true. My grandmother, Sarah Mooney, has always been one of my biggest supporters in everything I have chosen to do. I cannot thank my parents, Paul and Rebecca Wiltz, enough for everything they have done for me. Not only are they good parents, but they are two of my closest friends. Without the love and support of my family, none of this would have been possible. v TABLE OF CONTENTS Page ACKNOWLEDGEMENTS.............................................................................................................v LIST OF TABLES...........................................................................................................................x LIST OF FIGURES ...................................................................................................................... xii CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW .....................................................1 Distribution and Dispersal.........................................................................................3 Landscape and Community Ecology.........................................................................6 Chemical Ecology ...................................................................................................10 Pest Status................................................................................................................22 Control.....................................................................................................................23 Spatial Analysis in Entomology ..............................................................................28 References Cited......................................................................................................33 2 ACTIVITY OF BIFENTHRIN, CHLORFENAPYR, FIPRONIL, AND THIAMETHOXAM AGAINST AGRGENTINE ANTS (HYMENOPTERA: FORMICIDAE).......................................................................................................64 Abstract ...................................................................................................................65 Introduction .............................................................................................................66 Materials and Methods ............................................................................................67 Results .....................................................................................................................72 Discussion ...............................................................................................................75 vi References Cited......................................................................................................81 3 ACTIVITY OF BIFENTHRIN, CHLORFENAPYR, FIPRONIL, AND THIAMETHOXAM AGAINST RED IMPORTED FIRE ANTS (HYMENOPTERA: FORMICIDAE) .....................................................................95 Abstract ...................................................................................................................96 Introduction .............................................................................................................97 Materials and Methods ............................................................................................98 Results ...................................................................................................................102 Discussion .............................................................................................................104 References Cited....................................................................................................110 4 DETERRENCY AND TOXICITY OF ESSENTIAL OILS TO ARGENTINE ANTS AND RED IMPORTED FIRE ANTS (HYMENOPTERA: FORMICIDAE)......122 Abstract .................................................................................................................123 Introduction ...........................................................................................................124 Materials and Methods ..........................................................................................125 Results and Discussion..........................................................................................128 References Cited....................................................................................................132 5 A NOVEL DELIVERY METHOD FOR FIRE ANT TOXICANTS........................145 Abstract .................................................................................................................146 Introduction ...........................................................................................................147 Materials and Methods ..........................................................................................148 Results ...................................................................................................................152