ABSTRACT JETTON, ROBERT MILLER. Biological Control, Host Resistance, and Vegetative Propagation: Strategies and Tools for Management of the Invasive Hemlock Woolly Adelgid, Adelges tsugae Annand. (Under the direction of Dr. Fred P. Hain.) Biological control, host resistance, and vegetative propagation were evaluated as strategies and tools for management of the exotic pest hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae) in the southeastern U.S. The suitability of the balsam woolly adelgid (BWA), Adelges piceae Ratzeburg, as an alternate rearing host for Sasajiscymnus tsugae was compared to the primary prey HWA in a series of laboratory- based paired-choice and no choice (single-prey) experiments that tested adult feeding, oviposition, and long-term survival and immature development of the predator. Results indicated that S. tsugae will feed equally on eggs of both prey, will accept both prey for oviposition, and that the predator’s rate of immature development did not differ between the prey species, although fewer successfully completed egg to adult development on a diet of BWA compared to a diet of HWA. The long-term survival of predator adults was significantly influenced by both test prey type and the availability of a supplemental food source. The utility of confined releases for colonization of S. tsugae was evaluated in three field studies at forest and ornamental sites in western North Carolina. Predator reproduction, survival, and impact on HWA were investigated following the placement of fifteen adults (10♀:5♂) in mesh sleeves cages on adelgid infested hemlock branches for two or four weeks. In all three studies the predator reproduced inside sleeve cages and oviposition generally began within two or three weeks. Some adult predators were recovered during all three studies, indicating that S. tsugae can survive for up to one month inside mesh sleeve cages. Predator exclusion cages indicated significant local reductions in the density of adelgid ovisacs and aestivating nymphs, but these were not always correlated to the presence of the predator. Where S. tsugae was liberated from mesh sleeves two weeks after placement in the cages evidence of predator activity disappeared from the study sites within 4 months and establishment could not be documented during the study period. Differences in initial infestation rate and fecundity of HWA among three species of North American hemlock were evaluated in a climate-controlled greenhouse. Seedlings of adelgid-susceptible eastern, Tsuga canadensis (L.) Carrière, and Carolina, T. caroliniana Engelmann, hemlocks and putatively adelgid-resistant western hemlock (T. heterophylla Sargent) received either low inoculation (50 adeglid egg masses per seedling) or high inoculation (100 adelgid egg masses per seedling) treatments. Results showed very low and statistically similar rates of initial infestation on seedlings of Carolina and western hemlock and significantly higher rates on eastern hemlock seedlings. Adelgids that fed successfully on Carolina hemlock had significantly higher fecundity than those on either eastern or western hemlock, although this varied depending on inoculation treatment. The effects of auxin (NAA) concentration and cutting length on adventitious root formation in softwood stem cuttings from mature eastern and Carolina hemlocks were studied in a mist house. Overall rooting percentage (41%) and percent mortality (22%) were higher for eastern hemlock compared with Carolina hemlock (10% rooting and 13% mortality). Rooting percentage of each species responded differently to varying auxin concentrations (0, 1, 2, 4, 8 mM NAA), although the relationship between percent mortality and rooting was similar. Mortality among 6 cm stem cuttings was twice that observed for 3- cm cuttings of both species. However, 6 cm cuttings of eastern hemlock that did form adventitious roots had significantly more roots and longer total root length compared with 3- cm cuttings, a difference that was not significant for Carolina hemlock. Biological Control, Host Resistance, and Vegetative Propagation: Strategies and Tools for Management of the Invasive Hemlock Woolly Adelgid, Adelges tsugae Annand by Robert Miller Jetton A dissertation submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the Degree of Doctor of Philosophy Entomology and Forestry Raleigh, North Carolina 2008 APPROVED BY: ________________________ Fred P. Hain Chair of Advisory Committee ________________________ ________________________ Daniel J. Robison John Frampton Co-Chair of Advisory Committee ________________________ ________________________ David B. Orr John F. Monahan BIOGRAPHY Robert Miller Jetton was born in Greenville, South Carolina on January 2, 1974. He is the youngest of the four children of Dr. Robert L. Jetton of Tryon, North Carolina and Ms. Lee E. Churchill of Greenville, SC. He grew up in Greenville and graduated from Christ Church Episcopal School in June 1993. In September 1993, Robert enrolled in Furman University in Greenville, SC where he pursued and graduated with a Bachelor of Science degree in Biology in June 1997. From 1997 until 1999 Robert continued to live and work in Greenville where he was employed with the textile firm Nutex, Inc. He served as Director of Health, Safety, and Environmental Affairs and interim Plant Manager. In January of 1999, Robert enrolled as a graduate student at North Carolina State University. In 2002 he received a Master of Science degree in Forestry and Entomology studying under the direction of Dr. Daniel J. Robison and the Hardwood Research Cooperative. He then continued in graduate school at N.C. State to pursue a Doctor of Philosophy degree in Entomology and Forestry studying under the direction of Dr. Fred P. Hain. Since December of 2005, Robert has been employed full time as a Research Associate with the Camcore Cooperative while finishing his doctoral research and writing this dissertation. Camcore is an international tree conservation and domestication organization housed in the Department of Forestry and Environmental Resources at N.C. State, and Robert serves as the Project Leader for Camcore projects related to germplasm conservation of eastern and Carolina hemlocks. ii ACKNOWLEDGEMENTS My journey through graduate school at N.C. State would not have been possible without the support of numerous individuals. I must start by first thanking Fred Hain who saw enough potential in me to believe I could succeed in a Ph.D. program. He continued to encourage and support me at times when I was not living up to that potential or let the distractions of life get in the way. I have grown and matured more as an individual during my time as a student in Fred’s lab than at any other time in my life and hope to carry the many lessons Fred has taught forward in my career as a forest entomologist. I also thank Dan Robison who is the co-chair of my Ph.D. committee and was my major-advisor for my M.S. Dan rescued me from the life of a project- deprived graduate student when I first began my graduate career in 1999 and set me on my way as a forestry and entomology professional. Together, Fred and Dan have helped to instill in me a love and appreciation for forestry, entomology, and the scientific enterprise. Thanks also goes to the other members of my graduate committee: John Frampton, John Monahan, and David Orr. Their advice on experimental design, statistical analysis and constructive reviews of this dissertation has been invaluable. This entire process would have been impossible without funding support from the USDA Forest Service – Forest Health Protection, the Tree Fund, and Camcore. I also thank the other employees and graduate students in the forest entomology program and the Department of Forestry and Environmental Resources who provided much technical and moral support. Especially Felton Hastings, John Strider, Logan Williams, Leslie Newton, Adrian Duehl, Navdip Kaur, Kate Whitley Blinka, Micah Gardner, Kenneth Dobyns, Britt Hart, Janet Griffiths, David Titus, Jody Andrews, Manpreet Sandhu, Anthony LeBude, Chris Rosier, Mike Tighe, and Andy Whittier. Allen Cohen of Insect and Diet Rearing Research, LLC and iii surrogate member of the forest entomology program provided helpful reviews of several portions of this dissertation. I must also acknowledge and thank Bill Dvorak who had the patience and gave me the opportunity to take the reins of Camcore’s hemlock gene conservation program while finishing my Ph.D. research and writing. My work at Camcore has been the perfect opportunity to combine my interests in entomology and forestry for the good of the world’s forests. I also owe much to the staff at Camcore; Andy Whittier, Robert McGee, Juan Lopez, Gary Hodge, Willi Woodbridge, and Mike Tighe, for their encouragement and support. To the many friends I have made here at N.C. State and in Raleigh who offered much needed support and distraction I also offer thanks and gratitude. Especially Jamie and Jennifer Schuler, Peter and Denielle Birks, Mike and Kirsten Tighe, Jennifer Bennett and Jeff Phelan, Lori Hamburg, and Patty and David Alder. The support of my parents, my brothers and their families, and family friends has also been important, especially Eric and Holly Schwoebel who, in the early years of my graduate schooling, always made sure I never went more than a week without a great home-cooked meal. I reserve my greatest and heartfelt love and gratitude for my wife Jen Emerson.