Mississippi State University Scholars Junction Theses and Dissertations Theses and Dissertations 8-6-2021 Evaluation and mechanisms of host-plant resistance to the wireworm-Diabrotica-Systena complex in sweetpotatoes (Ipomoea batatas) and a commercial kairomone lure in Diabroticites Thomas J. Douglas [email protected] Follow this and additional works at: https://scholarsjunction.msstate.edu/td Recommended Citation Douglas, Thomas J., "Evaluation and mechanisms of host-plant resistance to the wireworm-Diabrotica- Systena complex in sweetpotatoes (Ipomoea batatas) and a commercial kairomone lure in Diabroticites" (2021). Theses and Dissertations. 5282. https://scholarsjunction.msstate.edu/td/5282 This Graduate Thesis - Open Access is brought to you for free and open access by the Theses and Dissertations at Scholars Junction. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of Scholars Junction. For more information, please contact [email protected]. Template B v4.3 (beta): Created by T. Robinson 01/2021 Evaluation and mechanisms of host-plant resistance to the wireworm-Diabrotica-Systena complex in sweetpotatoes (Ipomoea batatas) and a commercial kairomone lure in Diabroticites By TITLE PAGE Thomas J. Douglas Approved by: Fred Musser (Major Professor) Ashli Brown-Johnson Blake M. Layton Stephen L. Meyers Natraj Krishnan (Graduate Coordinator) Scott T. Willard (Dean, College of Agriculture and Life Sciences) A Thesis Submitted to the Faculty of Mississippi State University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Agricultural Life Sciences in the Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology Mississippi State, Mississippi August 2021 Copyright by COPYRIGHT PAGE Thomas J. Douglas 2021 Name: Thomas J. Douglas ABSTRACT Date of Degree: August 6, 2021 Institution: Mississippi State University Major Field: Agricultural Life Sciences Major Professor: Fred Musser Title of Study: Evaluation and mechanisms of host-plant resistance to the wireworm-Diabrotica- Systena complex in sweetpotatoes (Ipomoea batatas) and a commercial kairomone lure in Diabroticites Pages in Study: 54 Candidate for Degree of Master of Science An evaluation of host-plant resistance to the wireworm-Diabrotica-Systena (WDS) complex of root-feeding insects in sweetpotatoes was performed on a total of 15 cultivars and advanced lines over the course of 4 years (2017-2020). It was found that sweetpotatoes varieties can differ significantly in amount of damage incurred. Several mechanisms of resistance were proposed and tested: periderm toughness, dry weight percentage, and volatile organic chemical defenses. No significant difference was found amongst the varieties tested concerning the physical properties. Chemical analysis was limited in scope but did show some differences between a susceptible variety when compared to a resistant variety in the volatile chemical composition of the foliage. Finally, a commercial kairomone lure with sticky card for Diabroticites was tested for efficacy when compared to sweep net sampling throughout the season. No correlation could be found amongst the methods in terms of number and species of insects caught by each. ACKNOWLEDGEMENTS I would like to thank USDA-ARS for funding for this research and providing slips for advanced lines from their breeding program as well as LSU AgCenter and NC State. I would also like to express my gratitude to my advisor, Dr. Fred Musser, for his guidance over the course of the last two and a half years. I would like to thank the other members of my committee: Dr. Blake Layton, Dr. Ashli Brown, and Dr. Stephen Meyers for their assistance in providing feedback on my research ideas and on this thesis. This research would not have been possible without the assistance from the other members of the lab who helped with planting and harvesting: Beverly Catchot, Lauren Sanders, Farrar Misso, Shannon Oswald, Coty Martin, Chance Anderson, and Blaye Brasher. I would like to thank Jessi Collier and other members of the Hand chemistry lab for their assistance with the gas chromotagraphy and mass spectrometry analysis. Thank you to the faculty and staff of the Pontotoc Ridge-Flatwoods Branch Experiment Station for their hard work in replicating the research at their facility and providing slips each year from their plant beds. I am also grateful to Earp Farms, Topashaw Farms, and Ellison Farms for allowing me to put lures out in their fields. Last, but not least, I want to thank my family for their unwavering support during this whole process. iii TABLE OF CONTENTS ACKNOWLEDGEMENTS ........................................................................................................... iii LIST OF TABLES ...........................................................................................................................v LIST OF FIGURES ....................................................................................................................... vi CHAPTER I. INTRODUCTION .............................................................................................................1 Introduction .......................................................................................................................1 Insect Pests of Sweetpotatoes ......................................................................................2 Control of the WDS Complex .....................................................................................6 References .........................................................................................................................8 II. RESISTANCE TO THE WIREWORM-DIABROTICA-SYSTENA COMPLEX IN SWEETPOTATO (IPOMOEA BATATAS) CULTIVARS AND ADVANCED LINES .........................................................................................................................................10 Abstract ............................................................................................................................10 Introduction .....................................................................................................................10 Materials and Methods ....................................................................................................12 Results .............................................................................................................................13 Discussion ........................................................................................................................13 References .......................................................................................................................19 III. PHYSICAL AND CHEMICAL MECHANISMS OF RESISTANCE TO THE WIREWORM-DIABROTICA-SYSTENA COMPLEX IN SWEETPOTATO .............21 Introduction .....................................................................................................................21 Materials and Methods ....................................................................................................23 Results and Discussion ....................................................................................................25 References .......................................................................................................................30 IV. EFFICACY OF KAIROMONE TRAPS FOR CUCUMBER BEETLES IN SWEETPOTATOES .......................................................................................................33 Abstract ............................................................................................................................33 Introduction .....................................................................................................................33 Materials and Methods ....................................................................................................35 Results and Discussion ....................................................................................................36 References .......................................................................................................................42 iv LIST OF TABLES Table 2.1 Cultivars and advanced lines included at each trial site-year .....................................15 Table 2.2 Site-year agronomic details including replications, planting date, and information pertinent to that site-year ........................................................................16 Table 3.1 A list of Volatile Organic Compounds (VOCs) that could play a role in insect resistance identified in the sweetpotatoes tissues tested using Gas Chromotagraphy and Mass Spectrometry ..................................................................27 Table 4.1 Summary of Trap Catches by Sticky Cards\Kairomone Lure and Sweeps ................39 Table A.1 List of VOC’s Identified in Plant Defense .................................................................45 v LIST OF FIGURES Figure 2.1 Mean percent marketable yield (±SEM) of each line when compared to Beauregard; 2017-2020. Any values less than 100 yielded less than Beauregard, any values higher than 100 yielded more than Beauregard (SAS 9.4). .............................................................................................................................17 Figure 2.2 Mean WDS holes (±SEM) per potato by line; 2017-2020. Higher values indicate an increased susceptibility to WDS damage. Large standard error bars are a