University of Kentucky UKnowledge Theses and Dissertations--Entomology Entomology 2019 BIOLOGY AND MANAGEMENT OF THE SOYBEAN STEM BORER, Dectes texanus LeConte, IN KENTUCKY Izabela Gomes University of Kentucky, [email protected] Digital Object Identifier: https://doi.org/10.13023/etd.2019.448 Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Recommended Citation Gomes, Izabela, "BIOLOGY AND MANAGEMENT OF THE SOYBEAN STEM BORER, Dectes texanus LeConte, IN KENTUCKY" (2019). Theses and Dissertations--Entomology. 49. https://uknowledge.uky.edu/entomology_etds/49 This Master's Thesis is brought to you for free and open access by the Entomology at UKnowledge. It has been accepted for inclusion in Theses and Dissertations--Entomology by an authorized administrator of UKnowledge. For more information, please contact [email protected]. STUDENT AGREEMENT: I represent that my thesis or dissertation and abstract are my original work. Proper attribution has been given to all outside sources. I understand that I am solely responsible for obtaining any needed copyright permissions. I have obtained needed written permission statement(s) from the owner(s) of each third-party copyrighted matter to be included in my work, allowing electronic distribution (if such use is not permitted by the fair use doctrine) which will be submitted to UKnowledge as Additional File. I hereby grant to The University of Kentucky and its agents the irrevocable, non-exclusive, and royalty-free license to archive and make accessible my work in whole or in part in all forms of media, now or hereafter known. I agree that the document mentioned above may be made available immediately for worldwide access unless an embargo applies. I retain all other ownership rights to the copyright of my work. I also retain the right to use in future works (such as articles or books) all or part of my work. I understand that I am free to register the copyright to my work. REVIEW, APPROVAL AND ACCEPTANCE The document mentioned above has been reviewed and accepted by the student’s advisor, on behalf of the advisory committee, and by the Director of Graduate Studies (DGS), on behalf of the program; we verify that this is the final, approved version of the student’s thesis including all changes required by the advisory committee. The undersigned agree to abide by the statements above. Izabela Gomes, Student Dr. Raul T. Villanueva, Major Professor Dr. Kenneth F. Haynes, Director of Graduate Studies BIOLOGY AND MANAGEMENT OF THE SOYBEAN STEM BORER, Dectes texanus LeConte, IN KENTUCKY THESIS A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in the College of Agriculture, Food and Environment at the University of Kentucky By Izabela Gomes Lexington, Kentucky Director: Dr. Raul T. Villanueva, Professor of Entomology Lexington, Kentucky 2019 Copyright c Izabela Gomes 2019 ABSTRACT OF THESIS BIOLOGY AND MANAGEMENT OF THE SOYBEAN STEM BORER, Dectes texanus LeConte, IN KENTUCKY Dectes texanus LeConte (Coleoptera: Cerambycidae) is a longhorn beetle species en- demic to eastern United States. Originally described as a pest of weeds from the family Asteraceae, D. texanus has expanded its host range and is found infesting the stems of soybeans, Glycine max (L.) through the southwestern and middle United States. Female D. texanus chews a hole in the epidermis of a petiole and oviposits on it. Then, the D. texanus larva depletes all the pith of the stem making a tunnel down to the base of the plant and girdle the stem about 5 cm above the soil line. When a force is applied to the girdling point, generally weather related (i.e. strong winds), the plant lodges. While D. texanus phenology has been described for some states, this topic has yet to be explored in Kentucky. The objectives of this study were: 1) to describe the life cycle and behavior of D. texanus in soybeans in Western Kentucky, 2) to study the effect of the stem diameter on the incidence of D. texanus infestations, 3) to evaluate the susceptibility of full-season and double-crop soybeans to D.texanus infestations, 4) investigate the efficacy of seed treatment in reducing D. texanus infestations, 5) to determine effects of D. texanus larval feeding in the phys- iological yield of soybeans. The results of these studies showed that: 1) there was no distinct peak of D. texanus emergence detected in the 2018 and 2019 growing seasons and pupation period varied with year and location; the best sampling period for D. texanus population should occur between 1000 and 1600 hours during the peak season with either a 5-gallon white plastic bucket or sweep net; 2) the probability of finding D. texanus infesting soybeans was higher when the stem diameter is larger than 9 mm, and smaller than 11 mm; 3) double-crop soybeans had reduced infestations of D. texanus because these soybean plants are not a suitable host when D. texanus was active ovipositing and the pith was not fully developed; 4) seeds treated with imida- cloprid did not influence D. texanus infestation on soybeans, larvae presence in main and lateral stems, and parasitism occurrences; and 5) D. texanus did not affect seeds and pods attributes (pod width, length, height and weight), and yield. The latter may occur because feeding of D. texanus larva does not interfere on photosynthesis or nutrient transportation during seed fill. Keywords: life cycle, longhorn beetle, seed treatment, yield Izabela Gomes December 13, 2019 BIOLOGY AND MANAGEMENT OF THE SOYBEAN STEM BORER, Dectes texanus LeConte, IN KENTUCKY By Izabela Gomes Dr. Raul T. Villanueva Director of Thesis Dr. Kenneth F. Haynes Director of Graduate Studies December 13, 2019 ACKNOWLEDGMENTS First and foremost, I would like to thank my advisor, Dr. Villanueva, for the opportunity to become a graduate research assistant in 2017. I have learned much about myself, entomology, and various research practices throughout this process. Thank you to Dr. Bessin for always cleaning out the extra chair in your office for me when I had \one quick question" or needed to \talk for a minute." Your experience will continue to guide me on my path as a both a learner and researcher. To Dr. Obrycki, thank you for your kindness and patience. Your ability to use your knowledge to build students up is admirable and I am fortunate to have had you in my committee. A special thank you to Dr. Potter for believing in me and always watching out for me. Your legacy (aside from critical thinking about tritrophic interactions) is unconditionally caring and helping those around you. I certainly look up to you as both, a researcher and a human being. I'm thankful for the Department of Entomology staff, faculty, and student com- munity. You made it easy to find support and encouragement. To my lab mates, I appreciate always having you to count with. Thank you to everyone at the UK Research and Education Center for receiving me so well and making my project possible. I appreciate Kelsey, Josh and John for planting my soybeans. I am grateful for all the help from farm crew. Bobby and Scotty, thank you for going out of your way to help me and Yaz. Also, I will never forget Alex and Kaleb, the best interns anyone could ever have. To my colleague, Yaz, for the joy of calling you my friend. We've been on this path together, and there is no one else with whom I'd like to share this roller-coaster. Along with Yaz, thank you to all of the girls in the grad house; you girls made Princeton iii special. Katherine, thank you for helping with statistical analyses and reminding me that everything will be okay. To my mom and brother, I will never be able to show enough gratitude. Thank you mom for being my example and support, and for making sure I have had every op- portunity throughout my life. Thank you to my brother, Otavio, for your inspiration, care, and friendship. I'm grateful for the Borman family, which has received me in their lives with much love and unconditional support. In special, my fianc´e,Daniel, who has been with me during all of this journey. You have loved me in the hardest moments and believed in me when I couldn't do it myself. You're my rock! iv TABLE OF CONTENTS Acknowledgments . iii Table of Contents . v List of Tables . vi List of Figures . x Chapter 1 Introduction . 1 1.1 Taxonomy, morphology, biology and behavior . 3 1.2 Integrated pest management . 8 1.3 Impacts and need for more research . 19 1.4 Objectives . 20 Chapter 2 Biology and behavior of Dectes texanus LeConte (Coleoptera: Cer- ambycidae) in soybeans (Glycine max (L.) Merril) in Western Ken- tucky . 21 2.1 Introduction . 21 2.2 Materials and Methods . 24 2.3 Results . 29 2.4 Discussion . 33 Chapter 3 Effect of seed treatment on infestation and damage caused by Dectes texanus to full-season and double-crop soybean plants . 61 3.1 Introduction . 61 3.2 Materials and Methods . 64 3.3 Results . 67 3.4 Discussion . 68 Chapter 4 Impact of Dectes texanus LeConte (Coleoptera: Carambycidae) on physiological yield of Soybean, Glycine max (L.) Merril . 84 4.1 Introduction . 84 4.2 Materials and Methods . 86 4.3 Results . 90 4.4 Discussion . 95 Chapter 5 Summary . 117 References . 121 Vita . 130 v LIST OF TABLES 2.1 Soybean planting and harvest dates at Princeton for biology of D. texanus trials, KY, 2018 and 2019 . 25 2.2 Association of presence of D.