University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Dissertations and Student Research in Entomology Entomology, Department of 4-2020 Factors Influencing Wheat Curl Mite Aceria tosichella Keifer Dispersal Lindsay M. Overmyer University of Nebraska - Lincoln Follow this and additional works at: https://digitalcommons.unl.edu/entomologydiss Part of the Entomology Commons Overmyer, Lindsay M., "Factors Influencing Wheat Curl Mite Aceria tosichella Keifer Dispersal" (2020). Dissertations and Student Research in Entomology. 65. https://digitalcommons.unl.edu/entomologydiss/65 This Article is brought to you for free and open access by the Entomology, Department of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Dissertations and Student Research in Entomology by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. FACTORS INFLUENCING WHEAT CURL MITE ACERIA TOSICHELLA KEIFER DISPERSAL by Lindsay M. Overmyer A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfilment of Requirements For the Degree of Master of Science Major: Entomology Under the Supervision of Professor Gary L. Hein Lincoln, Nebraska May 2020 FACTORS INFLUENCING WHEAT CURL MITE ACERIA TOSICHELLA KEIFER DISPERSAL Lindsay M. Overmyer, M.S. University of Nebraska, 2020 Advisor: Gary L. Hein The wheat curl mite (Aceria tosichella Keifer) (WCM) is a vector of three plant viruses to wheat (Triticum aestivum L.) including: Wheat streak mosaic virus (WSMV), Triticum mosaic virus (TriMV), and High Plains wheat mosaic virus. This wheat-mite- virus complex causes significant yield loss in winter wheat across the Great Plains. Management of WCM host plants during the time between wheat harvest and planting of the new wheat crop (the green bridge) is critical in reducing potential risk and loss from this complex. The primary green bridge host, in the central Great Plains, is volunteer wheat. If volunteer wheat is not managed (via herbicide or tillage application), it can serve as a host in which mite populations can build up and later be dispersed by the wind into neighboring wheat fields, causing virus spread. Because population dynamics in vegetative volunteer wheat is not well understood, two studies were designed to focus on WCM population buildup and dispersal (subsequent virus spread). Differential mite populations were established in both studies by using viruses and/or virus resistant wheat varieties due to their impact on mite reproduction rates. Mite reproduction is negatively impacted by TriMV and positively by WSMV. ‘Mace’, a virus resistant variety, was used to maintain plant condition and derive elevated mite populations. Virus symptoms were monitored by measuring plant relative chlorophyll content. In a greenhouse study, mite-infested wheat was placed in wind tunnels every 7-10 days to evaluate mite dispersal from virus-infected wheat. A field study was also conducted in which mite dispersal (i.e. virus spread) was monitored around a single infested plant in a plot. Results indicated that mite density was the primary factor determining the extent of mite dispersal and virus spread. In addition, temperature impacted the extent of mite population build up and virus spread. Both studies will aid in the development of more accurate predictive risk models of virus risk and contribute to improved management of this wheat-mite-virus complex. i ACKNOWLEDGMENTS First, I would like to thank my advisor, Dr. Gary Hein, who has shaped me into the scientist I am. The opportunities you provided have helped me develop skills from analyzing data, communicating information through video, managing a lab, training new students, and more. I would like to also thank Drs. Stephen Wegulo and Jeffrey Bradshaw for serving on my committee. I appreciate their valuable input and guidance on thesis corrections and the extension videos that we have created for the wheat-mite-virus complex. I also would like to thank Drs. Justin McMechan, Tamra Jackson-Ziems, Robert Wright, and Thomas Hunt for the numerous Extension presentation opportunities which have allowed me to further develop my presentation skills and confidence in presenting new material to Nebraska producers and crop consultants. There have been many people that have aided in my research in the Hein lab throughout my degree. My greenhouse research required building three wind tunnels, and this would not have been possible without Dr. Doug Golick’s woodshop. Zach Rystrom was instrumental in planting and maintaining my field research plots. It is necessary to thank Jennifer Foster, Grace Lowe, Gabriela Inveninato Carmona, and Jacob Nikodym for data collection. I cannot thank Elliot Knoell enough as he has helped with both of my studies, especially through taking SPADs on plants in my research plots. He was very supportive in lab with lending a hand in counting mites or whatever situation arose and has become a great friend. Dr. Wiktoria Szydlo, a visiting scientist from Poland, joined our lab for a year and provided support for my projects as well, and lightened days in lab. I want to extend thanks to Dr. Yeyin Shi and Jiating in aiding in collecting spectral ii reflectance data and sorting through the vegetative indices for my field study. Lastly, Kelsey Karnick provided statistical guidance and feedback through the entire data analysis process. The entomology support staff including Jeri Cunningham, Marilyn Weidner, Marissa Kemp, and Kathy Schindler always had answers to my questions or figured out who to ask next. My fellow entomology graduate students, Doctor of Plant Health students, and alumni have provided so much encouragement along this journey in pursing two degrees simultaneously. I want to thank my family for their continuous support through this process, especially my parents, Alan and Jude and my brother Austin Overmyer. Words cannot describe the moral support and endless phone calls to Lauren Samuel, Catlin Pauley, and Dr. Lee Briese in helping me to continue through grad school. iii TABLE OF CONTENTS ACKNOWLEDGMENTS ................................................................................................... i LIST OF TABLES .............................................................................................................. v LIST OF FIGURES ........................................................................................................... vi CHAPTER 1: LITERATURE REVIEW ........................................................................... 1 Introduction ..................................................................................................................... 2 Wheat Curl Mite Classification ....................................................................................... 3 Wheat Curl Mite Biology and Ecology ........................................................................... 4 Alternative Hosts ............................................................................................................. 7 Mite Dispersal ................................................................................................................. 8 Viruses Transmitted ...................................................................................................... 10 Virus Transmission ....................................................................................................... 15 Management of the Virus Complex .............................................................................. 16 Reflectance as a Tool for Pathogen Detection .............................................................. 19 Literature Cited ............................................................................................................. 22 CHAPTER 2: DISPERSAL OF WHEAT CURL MITE FROM VIRUS INFECTED WHEAT IN A GREENHOUSE ........................................................................... 30 Introduction ................................................................................................................... 31 Material and Methods ................................................................................................... 34 Results ........................................................................................................................... 40 iv Discussion ..................................................................................................................... 43 Literature Cited ............................................................................................................. 46 Figures ........................................................................................................................... 48 CHAPTER 3: DISPERSAL OF WHEAT CURL MITE POPULATION DENSITIES WITHIN VOLUNTEER WHEAT ....................................................................... 53 Introduction ................................................................................................................... 54 Material and Methods ................................................................................................... 57 Results ........................................................................................................................... 65 Discussion ..................................................................................................................... 73 Literature Cited ............................................................................................................