Biology and management of the sugarcane aphid, Melanaphis sacchari (Zehntner), a new pest of sorghum, Sorghum bicolor (L.), in Alabama by Adrian Joseph Pekarcik A thesis submitted to the Graduate Faculty of Auburn University in partial fulfillment of the requirements for the Degree of Master of Science Auburn, Alabama Dec. 10, 2016 Key words: Sugarcane aphid, Melanaphis sacchari, sorghum, integrated pest management Copyright 2016 by Adrian Joseph Pekarcik Approved by Alana Jacobson, Chair, Assistant Professor of Entomology Kathy Flanders, Professor of Entomology Scott Santos, Professor of Biological Sciences David Held, Assistant Professor of Entomology Abstract The sugarcane aphid, Melanaphis sacchari (Zehntner), emerged as a new pest of sorghum in Texas and Louisiana in 2013, and has since spread rapidly throughout the Southern United States. Management of sugarcane aphid is difficult due to its rapid reproductive rate, our lack of knowledge on the biology and ecology of this emerging pest, and limited data on management options. The overall objective of this research was to develop an integrated pest management program for sugarcane aphid. Small plot research trials were conducted at several locations throughout Alabama to: 1) evaluate the efficacy of foliar and seed applied insecticides, 2) assess commercially available sorghum varieties for resistance and/or tolerance to sugarcane aphid, and 3) determine the most effective combination of these tactics for sugarcane aphid management in Alabama. The addition of all seed treatments including Cruiser® 5FS, Gaucho® 600, NipsIt® Inside, and Poncho® 600 managed populations below treatment threshold for at least 47 days after planting. Foliar insecticides showed that both rates of Sivanto® 200SL maintained populations below treatment threshold for 27 and 34 days after treatment, while Centric® 40WG and both rates of Transform® WG provided efficacy for 20 days after treatment. Several sorghum varieties including DeKalb 37-07, DowAg 1G588, DowAg 1G851, and Pioneer 83P17 showed high levels of tolerance to sugarcane aphid, however these results varied upon location. The most effective treatment combinations tested that produced the highest yields were early-planted and used Pioneer 83P17 with ii or without the addition of seed treatments. All early-planted treatments required one insecticide application, while only one of the late-planted treatments required one, however all late-planted treatments produced lower yields than early-planted treatments. iii Acknowledgements Without the encouragement and inspiration from various faculty mentors throughout my post-secondary education I would have never identified my passion for agriculture. Growing up in Northeast Ohio, I quickly learned about the effects of pollution in water systems (Cleveland, the mistake-on-the-lake). At Ohio Wesleyan University I would eventually learn through my professors’ personal experiences about agriculture’s contributions to the development of modern society as well as the potential for negative consequences on the ecosystem as a byproduct of mismanagement. This was apparent when learning about the effects of agricultural runoff on Grand Lake St. Mary in Northwest Ohio. It was at Auburn University during my time with Dr. Alana Jacobson that I was able to learn first-hand about agricultural processes and the necessity of them. I would like to thank her for the constant support and guidance she has offered these past two years. Dr. Jacobson’s hard work and determination has made a lasting impact on my interest for row crop integrated pest management, an aspect of ecology I had never even considered. However, I have learned how rewarding pest management can be when done properly and quickly developed a passion for row crop entomology. I owe many thanks to Dr. Scott Santos who consistently provided advice in regard to potential molecular studies which will have a large influence in regard to future research. I owe a debt of gratitude to Dr. Kathy Flanders who worked tirelessly in relaying sugarcane aphid information for the state iv of Alabama and ensuring farmers were kept up to date with the status of sugarcane aphid on sorghum. In addition, I would like to thank Dr. David Held for his constant support of the project and contributions to editing. I also want to acknowledge Dr. Held for his efforts in providing feedback and assistance with the entomology debate team. I would not have been able to accomplish this research without the assistance of several lab members and Dr. Jacobson, who spent many hours in the blazing Alabama sun to count aphids. Lastly, I would like to thank my family and friends from home who have provided endless support despite our distance apart. v Table of Contents Abstract ............................................................................................................................ii Acknowledgements ........................................................................................................ iiv List of Tables ................................................................................................................... iii List of Figures .................................................................................................................. iii CHAPTER 1 REVIEW OF LITERATURE ........................................................................ 1 Worldwide distribution .................................................................................................. 2 Biology and life history ................................................................................................. 3 Population genetics ...................................................................................................... 7 Aphid migration and dispersal ...................................................................................... 9 Damage and crop losses in North America ................................................................ 11 Integrated pest management ..................................................................................... 12 Chemical control ........................................................................................................ 15 Cultural control ........................................................................................................... 18 Biological control ........................................................................................................ 21 References Cited .......................................................................................................... 24 CHAPTER 2 EVALUATION OF INSECTICIDE EFFICACY FOR MANAGEMENT OF Melanaphis sacchari (Zehntner) ON Sorghum bicolor (L.), IN ALABAMA ..................... 38 Abstract ......................................................................................................................... 38 Introduction ................................................................................................................... 40 Materials and Methods .................................................................................................. 42 Seed treatment residual activity ................................................................................. 42 Insecticide efficacy ..................................................................................................... 43 Statistical analysis ...................................................................................................... 45 Results .......................................................................................................................... 46 Seed treatment residual activity ................................................................................. 46 Gulf Coast Research and Extension Center ........................................................... 46 vi E.V. Smith Plant Breeding Unit. .............................................................................. 47 Insecticide efficacy ..................................................................................................... 49 Brewton Agricultural Research Unit. ....................................................................... 49 Wiregrass Research and Extension Center. ........................................................... 50 Discussion ..................................................................................................................... 52 References Cited .......................................................................................................... 55 CHAPTER 3 EVALUATION OF COMMERCIALLY AVAILABLE SORGHUM VARIETIES FOR RESISTANCE AND TOLERANCE TO SUGARCANE APHID IN ALABAMA ..................................................................................................................... 71 Abstract ......................................................................................................................... 71 Introduction ................................................................................................................... 72 Materials and Methods .................................................................................................. 73 Statistical analysis ...................................................................................................... 75 Results .......................................................................................................................... 76 Brewton Agricultural Research Unit ..........................................................................