University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 12-2009 Nontarget host utilization of thistle species by introduced biological control agents and spatial prediction of non-target feeding habitats Gregory J. Wiggins University of Tennessee - Knoxville Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Plant Sciences Commons Recommended Citation Wiggins, Gregory J., "Nontarget host utilization of thistle species by introduced biological control agents and spatial prediction of non-target feeding habitats. " PhD diss., University of Tennessee, 2009. https://trace.tennessee.edu/utk_graddiss/641 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Gregory J. Wiggins entitled "Nontarget host utilization of thistle species by introduced biological control agents and spatial prediction of non-target feeding habitats." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Plants, Soils, and Insects. Jerome F. Grant, Major Professor We have read this dissertation and recommend its acceptance: Paris L. Lambdin, Jack W. Ranney, John B. Wilkerson Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) To the Graduate Council: I am submitting herewith a dissertation written by Gregory James Wiggins entitled “Non- target host utilization of thistle species by introduced biological control agents and spatial prediction of non-target feeding habitats.” I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, with a major in Plants, Soils and Insects. Jerome F. Grant, Major Professor We have read this dissertation and recommend its acceptance: Paris L. Lambdin Jack W. Ranney John B. Wilkerson Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official student records.) Non-target host utilization of thistle species by introduced biological control agents and spatial prediction of non-target feeding habitats A Dissertation Presented for The Doctor of Philosophy Degree The University of Tennessee, Knoxville Gregory J. Wiggins December 2009 Copyright © 2009 by Greg Wiggins All rights reserved. ii ACKNOWLEDGEMENTS I thank my major professor, Dr. Jerome F. Grant, for his guidance and support throughout this project. I would also like to thank the members of my graduate committee, Dr. Paris Lambdin, Dr. Jack Ranney, and Dr. John Wilkerson, for their attention and consideration of my research. I thank Dr. Ann Reed for her assistance with statistical analyses. I thank Dr. Frank van Manen for his assistance with habitat and spatial analysis. Special thanks to Dr. Charles O’Brien and Dr. Robert Anderson who confirmed identifications of weevil specimens collected during this project. I also thank Dr. Eugene Wofford for coordinating use of the University of Tennessee Herbarium. Many thanks to Renee Follum for her assistance with establishment of field sites and collection of data for caged plant and phenology studies. In addition, many thanks to the following people for assisting me in collection of data throughout the project: Amy and David Asbury, Isaac Deal, Josh Grant, Abdul Hakeem, Jared Oakes, David Paulsen, Coleman Timberlake, Alan Wallace, and Tracey Wiggins. Funding for this research was provided, in part, by the Environmental Protection Agency Greater Research Opportunities Fellowship program (fellowship #916586). I would like to thank my parents, Danny and Alice Wiggins, who have always loved and encouraged me throughout any endeavor I undertake. I would also like to thank Jimmy and Ginny Ellis for their continued care and support. Finally, I thank my wife and best friend Tracey Wiggins, whose loving friendship, tireless optimism, and boundless understanding make every day beautiful. iii ABSTRACT Rhinocyllus conicus Fröelich and Trichosirocalus horridus (Panzer) were introduced from Europe into North America as biological control agents of the exotic weed species Carduus nutans L. Concern exists over the feeding of these weevils on at least 25 species of native Cirsium thistles. Research was conducted to 1) estimate phenological synchrony of the eight thistle species in Tennessee with R. conicus and T. horridus, 2) investigate naturally-occurring populations of the five native Cirsium thistle species for non-target activity by R. conicus and T. horridus, 3) quantify the impacts to plants of each thistle species to feeding of R. conicus and T. horridus, and 4) identify potential areas of non-target feeding by the weevils using spatial analysis. Phenologies of two native species, C. carolinianum and C. horridulum, are synchronous with R. conicus reproduction, and all eight thistle species are phenologically synchronous with the reproduction of T. horridus. No non-target activity by R. conicus was observed in naturally-occurring populations of Cirsium thistles, but adults of T. horridus were documented for the first time on the native species C. carolinianum, C. horridulum, and C. muticum. In caged plant studies, larvae of R. conicus completed development in heads of C. carolinianum and C. horridulum and reduced seed numbers of both native species. Basal meristems of all eight thistle species exposed to T. horridus were damaged at varying levels in caged plant studies, but no other impacts to plants were observed. Spatial analyses showed associations between Mahalanobis distance values and plant counts of Carduus nutans and Cirsium carolinianum in predicted habitats, and the occurrence of Carduus nutans was associated with the occurrence of both weevil species in these habitats. About 12% of the total study area consisted of habitats where C. nutans iv and Cirsium carolinianum overlap. The potential exists for these weevils to utilize native Cirsium species found in Tennessee as plant hosts. The spatial model developed during this study not only allows potential monitoring of populations of C. carolinianum to be more targeted, but also may be modified to apply to other systems involving interactions among introduced and native species. v TABLE OF CONTENTS Chapter Page CHAPTER I. LITERATURE REVIEW............................................................................. 1 Invasive Species.............................................................................................................. 1 A Model System: Musk Thistle and Introduced Biological Control Agents................ 13 Objectives of Research ................................................................................................. 27 CHAPTER II. PHENOLOGIES OF NATIVE AND INTRODUCED THISTLE SPECIES AND THEIR SYNCHRONY WITH INTRODUCED BIOLOGICAL CONTROL AGENTS OF CARDUUS NUTANS.................................................................................. 29 Introduction................................................................................................................... 29 Materials and Methods.................................................................................................. 32 Results and Discussion ................................................................................................. 36 CHAPTER III. NON-TARGET ACTIVITY OF RHINOCYLLUS CONICUS AND TRICHOSIROCALUS HORRIDUS ON NATIVE CIRSIUM POPULATIONS IN TENNESSEE .................................................................................................................... 58 Introduction................................................................................................................... 58 Materials and Methods.................................................................................................. 60 Results and Discussion ................................................................................................. 63 CHAPTER IV. IMPACTS OF LARVAL FEEDING OF RHINOCYLLUS CONICUS ON PLANT REPRODUCTION AND LEVELS OF HOST UTILIZATION ON FIELD- CAGED TARGET AND NON-TARGET THISTLES IN TENNESSEE ....................... 66 Introduction................................................................................................................... 66 Materials and Methods.................................................................................................. 70 Results and Discussion ................................................................................................. 76 CHAPTER V. PLANT RESPONSES TO TRICHOSIROCALUS HORRIDUS ON FIELD-CAGED NON-TARGET NATIVE THISTLES IN TENNESSEE ..................... 87 Introduction................................................................................................................... 87 Materials and Methods.................................................................................................. 89 Results and Discussion ................................................................................................