Mississippi State University Scholars Junction Theses and Dissertations Theses and Dissertations 5-1-2020 Refinement and alidationv of soybean looper (Chrysodeixis includens) (Walker) thresholds in Mississippi soybeans (Glycine max (L.) Merr.) Mary Huff Follow this and additional works at: https://scholarsjunction.msstate.edu/td Recommended Citation Huff, Mary, "Refinement and alidationv of soybean looper (Chrysodeixis includens) (Walker) thresholds in Mississippi soybeans (Glycine max (L.) Merr.)" (2020). Theses and Dissertations. 3750. https://scholarsjunction.msstate.edu/td/3750 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]. Refinement and validation of soybean looper, Chrysodeixis includens (Walker), thresholds in Mississippi soybean Glycine max (L.) Merr. By TITLE PAGE Mary Kathryn Huff 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 May 2020 Copyright by COPYRIGHT PAGE Mary Kathryn Huff 2020 Refinement and validation of soybean looper (Chrysodeixis includens) (Walker) thresholds in Mississippi soybeans (Glycine max (L.) Merr.) By APPROVAL PAGE Mary Kathryn Huff Approved: ____________________________________ Donald R. Cook (Major Professor) ____________________________________ Angus L. Catchot Jr. (Co-Major Professor) ____________________________________ Jeffrey Gore (Committee Member) ____________________________________ Fred R. Musser (Committee Member) ____________________________________ Jon Trenton Irby (Committee Member) ____________________________________ Kenneth O. Willeford (Graduate Coordinator) ____________________________________ George M. Hopper Dean College of Agriculture and Life Sciences Name: Mary Kathryn Huff ABSTRACT Date of Degree: May 1, 2020 Institution: Mississippi State University Major Field: Agricultural Life Sciences Major Professors: Donald R. Cook and Angus L. Catchot Jr. Title of Study: Refinement and validation of soybean looper (Chrysodeixis includens) (Walker) thresholds in Mississippi soybeans (Glycine max (L.) Merr.) Pages in Study: 88 Candidate for Degree of Master of Science Experiments were conducted to refine and validate the soybean looper, Chrysodeixis includens (Walker) threshold in Mississippi soybeans, Glycine max. (L.) Merr. Equivalencies between sweep net and drop cloth sampling methods were evaluated, overall the sweep net was more effective at capturing soybean looper larvae greater than third instar and larvae less than or equal to third instar when compared to the drop cloth method. Feeding studies were conducted to determine the feeding rates of each instar, results showed that fifth instar larvae consume the greatest amount of leaf tissue, and larvae greater than or equal to third instar consume more leaf tissue than larvae less than third instar. Observed and expected/predicted defoliation rates were calculated. Observed defoliation was lower than predicted defoliation possibly due to field environmental conditions. Using data in combination with published data from other studies, three prediction models were created for the R3, R5, and R6 growth stage. DEDICATION This thesis is dedicated to my late great-grandmother, Gwendolyn King. The memory of her unconditional love and her unshakable strength have always driven me and will continue to do so all the days of my life. I could spend the rest of my days describing the impact she made on my life, but her impact and her love are best summed up by Albus Dumbledore in the Harry Potter series by J.K. Rowling when he said, “…love as powerful as [her’s] for you leaves its own mark. Not a scar, no visible sign… to have been loved so deeply, even though the person who loved us is gone, will give us some protection forever.” And for her love, guidance, and presence I will be forever grateful. Her greatest wish in life was to see me graduate high school and although she never got to see that wish come to fruition, I can only hope that she is looking down on me now and that she is proud. This thesis is also dedicated to my family. To my parents, Watt and Susie Huff, I could not be more grateful for the two of you. Even though you still don’t know exactly what I’m getting a degree in, and for a time thought I was getting a master’s degree in soybeans, your support has never wavered. I am so incredibly thankful for the values you have instilled in me and for your unconditional love and support. To my cousins, Lauren, Sarah, and Rachel; the constant laughs and honest advice from the three of you has been the greatest support system I could ever ask for. ii ACKNOWLEDGEMENTS I would first like to acknowledge my advisors and committee members. I cannot thank you enough for giving me this opportunity to learn and to pursue a Master’s degree. The knowledge and advice you all have given me will never be taken for granted, nor will the patience and guidance you have shown me. Next I would like to acknowledge my fellow graduate students. To Joel Moor and Read Kelly, thank you for helping me navigate my way through classes and writing papers, I could not have passed without you. To Will Hardman, Sara Barrett, Russ Godbold, and Cade Francis, thank you for always being there when I needed a helping a hand. When I look back on my time in grad school I will always remember the laughs and long conversations, you all have been (and hopefully will continue to be) the very best of friends. To the full time staff and summer workers at DREC: Aaron Leininger, Meg Cutts, Neil Wright, Hauff Carpenter, Harper Horton, Rainer Hodges, Duncan Henson, Jamarion Merrill, Trey Freeland, Hunter Price, Jasmine Warren, and countless others that jumped in and lent a hand. I could not have built cages, pulled leaves off of hundreds of plants, weighed larvae, or sampled fields without you. No amount of lunches bought or thank you’s said will be enough to show my gratitude to all of you. iii TABLE OF CONTENTS DEDICATION ................................................................................................................................ ii ACKNOWLEDGEMENTS ........................................................................................................... iii TABLE OF CONTENTS ............................................................................................................... iv LIST OF TABLES ......................................................................................................................... vi LIST OF FIGURES ..................................................................................................................... viii CHAPTER I. LITERATURE REVIEW .................................................................................................1 Soybeans ............................................................................................................................1 Soybean Defoliation ..........................................................................................................3 Sampling Larvae on Soybeans ..........................................................................................4 Soybean Looper .................................................................................................................6 Soybean Thresholds .........................................................................................................11 References Cited ..............................................................................................................15 II. EVALUATION OF DROP CLOTH AND SWEEPNET SAMPLING METHODS FOR SOYBEAN LOOPER INFESTING SOYBEAN IN MISSISSIPPI ......................................................................................................22 Abstract ............................................................................................................................22 Introduction .....................................................................................................................22 Materials and Methods ....................................................................................................25 Results .............................................................................................................................27 Discussion ........................................................................................................................28 References Cited ..............................................................................................................38 III. EVALUATION OF SOYBEAN LOOPER LARVAL CONSUMPTION RATES ................................................................................................................40 Abstract ............................................................................................................................40 Introduction .....................................................................................................................41 Materials and Methods ....................................................................................................42 Results .............................................................................................................................44