Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1985 Natural Control and Spatial Distribution of Fall Armyworm (Spodoptera Frugiperda) Within Louisiana Corn Fields. Forrest Lee Mitchell Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Mitchell, Forrest Lee, "Natural Control and Spatial Distribution of Fall Armyworm (Spodoptera Frugiperda) Within Louisiana Corn Fields." (1985). LSU Historical Dissertations and Theses. 4143. https://digitalcommons.lsu.edu/gradschool_disstheses/4143 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 Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. 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Zeeb Road, Ann Arbor, Ml 48106 Copyright 1986 by Mitchell, Forrest Lee All Rights Reserved PLEASE NOTE: In all cases this material has been filmed in the best possible way from the available copy. Problems encountered with this document have been identified here with a check mark V . 1. Glossy photographs or p ag______ es 2. Colored illustrations, paper or print_______ 3. Photographs with dark backgrou nd _____ 4. Illustrations are poor copy_______ 5. Pages with black marks, not original copy______ 6. Print shows through as there is text on both sides of page _____ 7. Indistinct, broken or small print on several pages 8. Print exceeds margin requirements ______ 9. Tightly bound copy with print lost in spine_______ 10. Computer printout pages with indistinct print_______ 11. Page(s)____________ lacking when material received, and not available from school or author. 12. Page(s) _________ seem to be missing in numbering only as text follows. 13. Two pages num bered . Text follows. 14. Curling and wrinkled p ag es ______ 15. Dissertation contains pages with print at a slant, filmed as received __ 16. Other________________________________________ _________________________________ University Microfilms International NATURAL CONTROL AND SPATIAL DISTRIBUTION OF FALL ARMYWORM (SPODOPTERA FRUGIPERDA) WITHIN LOUISIANA CORN FIELDS 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 Forrest Lee Mitchell B.S., Texas A&M University, 1977 M.S., Texas A&M University, 1980 December 1985 ©1986 FORREST LEE MITCHELL All Rights Reserved ACKNOWLEDGEMENTS The completion of a doctoral degree is never an easy task, but I have been fortunate in having many friends and colleagues who assisted me. I greatly appreciate the patience and support of my major professor, Dr. J.R. Fuxa, and my committe members, Dr. T.C. Sparks, Dr. L.D. Newsom, Dr. J.B. Graves, Dr. B. Wilson, Dr. J. Larkin, Dr. D. Braymer, and Dr. A. D. Larson. Art Richter and Greg Warren were both frien d and co-w orker, and w ithout th e ir assistance my research would have gone awry more than once. Friends too numerous to mention made my time in Baton Rouge enjoyable and le ft me with unforgettable memories. Colleagues in entomological societies were always willing to listen and advise — they are the main reason entomology w ill always be a colorful and enjoyable profession. The patience and affection of my wife, Paula, shored me up through the hard times. Without her, I could not have accomplished this work. ii TABLE OF CONTENTS page ACKNOWLEDGEMENTS ............. ........................................................................ i i ABSTRACT...............................................................................................................v ii CHAPTER 1. INTRODUCTION AND LITERATURE REVIEW ............................ 1 2. SPATIAL DISTRIBUTION AND SAMPLING OF FALL ARMYWORM IN CORNFIELDS ................................................... 8 Materials and Methods ..................................................... 9 Results ..................................................................................... 12 Discussion .............................................................................. 32 3. MULTIPLE REGRESSION ANALYSIS OF A NUCLEAR POLYHEDROSIS VIRUS IN POPULATIONS OF FALL ARMYWORM IN CORNFIELDS ................................................... 34 Materials and Methods * ................................................... 34 Results ..................................................................................... 40 Discussion ...................... 54 4. MULTIPLE REGRESSION ANALYSIS OF PARASITISM OF FALL ARMYWORM BY THREE SPECIES OF LARVAL PARASITES................................................................................... 63 Materials and Methods ........................................ 64 Results .................. 65 Discussion ................................................................... 83 5. SEASONAL SUSCEPTIBILITY OF FALL ARMYWORM TO A NUCLEAR PLOYHEDROSIS VIRUS .......................................... 87 Materials and Methods ..................................................... 88 Results ..................................................................................... 90 Discussion .............................................................................. 105 REFERENCES CITED....... ............................................................................. 108 APPENDIX 1 ............................................................................ 117 APPENDIX 2 ............................................................................ 120 APPENDIX 3 ............................................................................ 123 VITA................................................................................................................... 126 iii LIST OF TABLES TABLE page 2.1 Chi-square probability levels for three distri­ butions fit to total fall armyworm populations collected in one-plant samples ...................................... 13 2.2 Chi-square probalility levels for three distri­ butions fit to total fall armyworm populations collected in five-plant samples .................................... 14 2.3 Chi-square probability levels for three distri­ butions fit to small fall armyworm collected from one-plant samples ..................................................... 15 2.4 Chi-square probability levels for three distri­ butions fit to small fall armyworm collected from five-plant samples ................................................... 16 2.5 Chi-square probability levels for three distri­ butions fit to medium fall armyworm collected from one-plant samples ..................................................... 18 2.6 Chi-square probability levels for three distri­ butions fit to medium fall armyworm collected from five-plant samples ................................................... 19 2.7 Chi-square probability levels for three distri­ butions fit to large fall armyworm collected from one-plant samples ........................................................ 20 2.8 Chi-square probability levels for three distri­ butions fit to large fall armyworm collected from five-plant samples ...................................................... 21 2.9 Number of samples required for p=0.20 accuracy for fa ll armyworm larvae sampled at varying densities (number/plant) in cornfields .................... 31 3.1 Variables tested for inclusion in fall armyworm NPV multiple regression models ...................................... 39 3.2 Distribution of infection and mortality in field collected