Louisiana State University LSU Digital Commons LSU Doctoral Dissertations Graduate School March 2019 Effects of Plant Viruses on Vectors and Non-vector Herbivores in Three Different Pathosystems Sunil Paudel Louisiana State University and Agricultural and Mechanical College, [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_dissertations Part of the Entomology Commons Recommended Citation Paudel, Sunil, "Effects of Plant Viruses on Vectors and Non-vector Herbivores in Three Different Pathosystems" (2019). LSU Doctoral Dissertations. 4870. https://digitalcommons.lsu.edu/gradschool_dissertations/4870 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Doctoral Dissertations by an authorized graduate school editor of LSU Digital Commons. For more information, please [email protected]. EFFECTS OF PLANT VIRUSES ON VECTORS AND NON-VECTOR HERBIVORES IN THREE DIFFERENT PATHOSYSTEMS A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Entomology by Sunil Paudel B. S., Tribhuvan University, 2008 M.S., University of Idaho, 2013 May 2019 ACKNOWLEDGEMENTS I would like to express my sincere gratitude to my major advisor, Dr. Jeffrey A. Davis for his continuous support throughout my graduate studies, for his patience, encouragement, and guidance that helped me to grow as a researcher and a critical thinker. I am also thankful to my dissertation committee members, Drs. Michael J. Stout, Fangneng Huang, Jeffrey W. Hoy, and Dean’s representative Dr. John C. Larkin for serving on my committee and providing me valuable suggestions and guidance for improvement. My sincere thanks go to Art Richter, Mark Murray, Monique de Souza, John Dryburgh, Colin Bonser, Scot Lee and all the members of soybean entomology laboratory for their help in carrying out my research projects and their friendship throughout this journey. I am always grateful to the unconditional support of my family members for this academic accomplishment. I owe special thanks to my wife, Shilpa Ghimire, for her love, support, understanding and patience throughout this journey. Last but not the least, my sincere thanks go to the Department of Entomology, all the faculty members, and all my friends for their friendship and company during my graduate studies here at Louisiana State University. ii TABLE OF CONTENTS ACKNOWLEDGEMENTS........................................................................................................ ii ABSTRACT ...............................................................................................................................v CHAPTER 1: GENERAL INTRODUCTION .............................................................................1 1.1. References ........................................................................................................................4 CHAPTER 2: LITERATURE REVIEW .....................................................................................7 2.1. Biology and life cycle of aphids ........................................................................................7 2.2. Aphid transmitted viruses, their biology, and management .............................................. 10 2.3. Why aphids are efficient virus vectors? ........................................................................... 16 2.4. Effects of plant viruses on behavior and performance of vectors and non-vectors ............ 17 2.5. Use of electrical penetration graph for study of vector feeding behavior .......................... 20 2.6. Study systems ................................................................................................................. 22 2.7. References ...................................................................................................................... 33 CHAPTER 3: THE FEEDING BEHAVIOR AND VECTOR POTENTIAL OF MELANAPHIS SACCHARI IN TRANSMITTING SORGHUM MOSAIC VIRUS TO SORGHUM .................... 50 3.1. Introduction .................................................................................................................... 50 3.2. Materials and Methods .................................................................................................... 58 3.3. Results ............................................................................................................................ 63 3.4. Discussion ...................................................................................................................... 66 3.5. References ...................................................................................................................... 70 CHAPTER 4: THE PREFERENCE BEHAVIOR AND LIFE HISTORY TRAITS OF MELANAPHIS SACCHARI ON SORGHUM MOSAIC VIRUS-INFECTED AND NON- INFECTED SORGHUM ........................................................................................................... 76 4.1. Introduction .................................................................................................................... 76 4.2. Materials and Methods .................................................................................................... 80 4.3. Results ............................................................................................................................ 85 4.4. Discussion ...................................................................................................................... 90 4.5. References ...................................................................................................................... 94 iii CHAPTER 5: IMPACTS OF CUCUMBER MOSAIC VIRUS AND SUNN-HEMP MOSAIC VIRUS ON FEEDING, GROWTH AND OVIPOSITION PREFERENCE OF TWO NON- VECTOR HERBIVORES ......................................................................................................... 97 5.1. Introduction .................................................................................................................... 97 5.2. Materials and Methods .................................................................................................... 99 5.3. Results .......................................................................................................................... 103 5.4. Discussion .................................................................................................................... 104 5.5. References .................................................................................................................... 106 CHAPTER 6: EFFECTS OF BELL PEPPER ENDORNAVIRUS ON MYZUS PERSICAE HOST PREFERENCE AND POPULATION DYNAMICS ............................................................... 112 6.1. Introduction .................................................................................................................. 112 6.2. Materials and Methods .................................................................................................. 114 6.3. Results .......................................................................................................................... 119 6.4. Discussion .................................................................................................................... 122 6.5. References .................................................................................................................... 124 CHAPTER 7: SUMMARY AND CONCLUSION ................................................................. 127 VITA ...................................................................................................................................... 131 iv ABSTRACT Plant viruses are an important component of agro-ecosystems and the knowledge of impacts they can cause on their hosts, and on different vectors and non-vector herbivores associated with the hosts, is very crucial in devising sound management strategies for virus disease and vector control in the landscape. The interactions between these components, however, are difficult to predict and vary according to the system under investigation. In order to understand some of these interrelationships, different sets of experiments were carried out in three different pathosystems to look at the impacts of plant viruses on vector and non-vector herbivores. Firstly, in Sorghum mosaic virus (SrMV)-sorghum (Sorghum bicolor L.) pathosystem, we found that Melanaphis sacchari (Zehntner) was attracted to virus infected sorghum but the population was negatively affected upon feeding on virus infected sorghum. Moreover, M. sacchari unlike Myzus persicae (Sulzer), failed to transmit SrMV, and we state based on our results that M. sacchari is a non-vector of SrMV. In Cucumber mosaic virus (CMV) and Sunn-hemp mosaic virus (ShMV) infected cowpea (Vigna unguiculata (L.) Walp), oviposition by adult Chrysodeixis includens (Walker) and Spodoptera frugiperda (Smith) was negatively affected whereas S. frugiperda larva benefitted upon feeding on CMV-infected host tissue. In our study with Bell pepper endornavirus (BPEV) in bell pepper (Capsicum annuum L.), we observed that M. persicae preferred virus-free leaves and performed poorly on virus infected leaf tissues. The mixed results we obtained on the impacts of plant viruses in different systems suggest that it is difficult to draw