University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Masters Theses Graduate School 12-2006 Established Predators of Fiorinia externa Ferris (Hemiptera: Diaspididae) on Eastern Hemlock (Tsuga canadensis (L.) Carriere) in Urban and Forest Sites Christine Ann Lynch University of Tennessee - Knoxville Follow this and additional works at: https://trace.tennessee.edu/utk_gradthes Part of the Plant Sciences Commons Recommended Citation Lynch, Christine Ann, "Established Predators of Fiorinia externa Ferris (Hemiptera: Diaspididae) on Eastern Hemlock (Tsuga canadensis (L.) Carriere) in Urban and Forest Sites. " Master's Thesis, University of Tennessee, 2006. https://trace.tennessee.edu/utk_gradthes/1726 This Thesis 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 Masters Theses 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 thesis written by Christine Ann Lynch entitled "Established Predators of Fiorinia externa Ferris (Hemiptera: Diaspididae) on Eastern Hemlock (Tsuga canadensis (L.) Carriere) in Urban and Forest Sites." I have examined the final electronic copy of this thesis for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Master of Science, with a major in Entomology and Plant Pathology. Paris Lambdin, Major Professor We have read this thesis and recommend its acceptance: Jerome Grant, Kevin Moulton, Rusty Rhea 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 thesis written by Christine Ann Lynch entitled “Established Predators of Fiorinia externa Ferris (Hemiptera: Diaspididae) on Eastern Hemlock (Tsuga canadensis (L.) Carriere) in Urban and Forest Sites.” I have examined the final electronic copy of this thesis for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Master of Science, with a major in Entomology and Plant Pathology. Paris Lambdin Major Professor We have read this thesis and recommend its acceptance: Jerome Grant Kevin Moulton Rusty Rhea Acceptance for the Council: Anne Mayhew Vice Chancellor and Dean of Graduate Studies (Original signatures are on file with official student records.) Established Predators of Fiorinia externa Ferris (Hemiptera: Diaspididae) on Eastern Hemlock (Tsuga canadensis (L.) Carriere) in Urban and Forest Sites A Thesis Presented for the Master of Science Degree The University of Tennessee, Knoxville Christine Ann Lynch December 2006 Copyright © 2006 by Christine Ann Lynch All rights reserved ii Acknowledgements I am grateful to everyone who assisted me during this research project. First, I acknowledge Dr. Paris Lambdin for challenging me with this project and answering my many questions. The assistance and guidance of my committee members, Dr. Jerome Grant, Dr. Kevin Moulton, and Rusty Rhea, are greatly appreciated. For expanding my knowledge of entomology, I want to thank Dr. Paris Lambdin, Dr. Jerome Grant, Dr. Kevin Moulton, and Dr. Reid Gerhardt. I would like to thank the following people for allowing me to sample the eastern hemlocks: Bill Hascher from Biltmore Estates, Charles Limebarger from Lynnhurst Cemetery, and Ken Childress from Bays Mountain Park. For support with statistical analysis, I recognize Dr. Ann Reed and Maria Weese. I extend my thanks to the following taxonomists: Dr. Robert Gordon from Northern Plains Entomology for identifying Scymnillus horni and Scymnus loweii, and Dr. Norman Penny from the California Academy of Sciences for identifying Conwentzia pineticola. This project would not have been possible without the financial support from Rusty Rhea and Richard Reardon of the U.S.DA. Forest Service. For assistance with field collections and for creating an enjoyable work environment, I want to thank Dave Paulsen, Don Plattner, Carla Dilling, and Toni Conatser. For providing Adelges tsugae (hemlock woolly adelgid), I extend my thanks to Isaac Deal. I would like to thank Greg Wiggins for his guidance throughout my Master’s program. For inspiring me to study entomology, I thank Dr. Robin Giblin-Davis and Dr. Rudolph Scheffrahn. I would like to thank Dr. Carl Barfield, Dr. Paul Choate, Dr. Glenn Hall, Dr. Donald Hall, and Dr. Philip Koehler at the University of Florida for preparing me well for this degree and future endeavors. I am very grateful to my parents for their encouragement and sacrifices made in order to provide me with an excellent education. Finally, I thank Justin Toombs for his advice, support, sampling assistance, and willingness to listen. iii Abstract A project was initiated in September 2004 to determine the indigenous predators of Fiorinia externa Ferris, the elongate hemlock scale (EHS), on eastern hemlock and their impact on the pest populations. Branch samples were taken monthly from four sites (two forest and two urban) in eastern Tennessee and western North Carolina to assess predator damage from October 2004 to April 2006. Predators of this exotic pest were collected from beat sheet samples from September 2004 to May 2006. Laboratory tests were conducted from field-collected predators to assess food consumption, feeding behavior, and intraguild competition among predators of EHS. From field samples, the average predator damage was 8.28% (range 4.72 to 9.84%) for the four sites, and predator damage was found throughout the year. Six predaceous species (Chilocorus stigma, Harmonia axyridis, Rhyzobius lophanthae, Scymnillus horni, Scymnus loweii, and Conwentzia pineticola) were documented to feed on EHS. There were 346 total adult predators, one pupa, and 157 larvae collected from September 2004 through May 2006. Rhyzobius lophanthae was the only predator collected throughout the year. The highest numbers of specimens collected were from the urban sites. Chilocorus stigma, R. lophanthae, and S. horni had the highest EHS consumption rates. From the functional tests, S. horni, R. lophanthae, and C. stigma exhibited different searching patterns for recognizing EHS as prey. Chilocorus stigma had the shortest prey recognition times, while R. lophanthae had the longest prey recognition times. Scymnus loweii did not feed during the functional tests. When four of the predators were tested in different combinations, all four exhibited aggressive tendencies, and this territorial behavior could cause feeding disruption. Rhyzobius lophanthae and S. horni consumed fewer Adelges tsugae females or immatures compared to EHS and were more prey specific. In fecundity tests, R. lophanthae most commonly laid eggs singly on a branch, needles, side of Petri dish, or filter paper than in clusters. It also laid eggs near or under EHS exuviae. Based on consumption and seasonal abundance, R. lophanthae, C. stigma, and S. horni should be further evaluated for use as biological control agents to complement the parasitoid, Encarsia citrina. (348 words) iv Table of Contents Chapter Page I. Literature review ..............................................................................................................1 Tsuga (hemlocks) ....................................................................................................1 Tsuga canadensis (L.) Carriere ...............................................................................1 Exotic pests of eastern hemlock ..............................................................................8 Fiorinia externa Ferris ..........................................................................................11 Fiorinia externa and Nuculaspis tsugae in Japan and the United States ..............18 Chemical control of elongate hemlock scale ........................................................21 Predators of elongate hemlock scale .....................................................................23 Research objectives ...............................................................................................33 II. Established predators and their impact on elongate hemlock scale on eastern hemlocks in forest and urban sites in the southern Appalachians ...................35 Introduction ...........................................................................................................35 Materials and methods ..........................................................................................37 Results....................................................................................................................41 Discussion .............................................................................................................57 III. Behavior, consumption, and competition of elongate hemlock scale predators .........59 Introduction ...........................................................................................................59 Materials and methods ..........................................................................................61 Results ...................................................................................................................66 Discussion .............................................................................................................81 IV. Conclusions .................................................................................................................83