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EXPLOITING the INSECTICIDAL POTENTIAL of the INVASIVE SIAM WEED, Chromolaena Odorata L

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EXPLOITING the INSECTICIDAL POTENTIAL of the INVASIVE SIAM WEED, Chromolaena Odorata L University of Ghana http://ugspace.ug.edu.gh EXPLOITING THE INSECTICIDAL POTENTIAL OF THE INVASIVE SIAM WEED, Chromolaena odorata L. (ASTERACEAE) IN THE MANAGEMENT OF MAJOR PESTS OF CABBAGE, Brassica oleracea var capitata AND THEIR NATURAL ENEMIES FOR ENHANCED YIELD IN THE MOIST SEMI- DECIDUOUS AGRO- ECOLOGICAL ZONE OF GHANA BY GODFRED NWOSU EZENA 10397344 THIS THESIS IS SUBMITTED TO THE UNIVERSITY OF GHANA, LEGON IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE AWARD OF MASTER OF PHILOSOPHY ENTOMOLOGY DEGREE INSECT SCIENCE PROGRAMME* UNIVERSITY OF GHANA LEGON JULY, 2015 *Joint Inter- Faculty International Programme for the Training of Entomologists in West Africa. Collaborating Departments: Animal Biology and Conservation Science (School of Biological Sciences) and Crop Science (School of Agriculture), College of Basic and Applied Sciences University of Ghana, Legon University of Ghana http://ugspace.ug.edu.gh DECLARATION This is to certify that this thesis, with exception of references to other works which have been duly acknowledged, is the results of research work undertaken by me, Godfred Nwosu Ezena, at the Forest and Horticultural Crops Research Centre (FOHCREC) towards the award of Master of Philosophy (M. Phil.) degree in Entomology at the African Regional Postgraduate Programme in Insect Science (ARPPIS), University of Ghana, Legon. GODFRED NWOSU EZENA (STUDENT) DR. CLEMENT AKOTSEN- MENSAH (SUPERVISOR) DR. KEN OKWAE FENING (SUPERVISOR) DR. ROSINA KYEREMATEN (ARPPIS CO-ORDINATOR) i University of Ghana http://ugspace.ug.edu.gh DEDICATION I dedicate this thesis to my dear wife, Mrs. Helena Ezena and my lovely daughters, Irene Ifeoma Adomah Ezena and Jessica Nkechi Dansowaa Ezena, for their sacrifices during this course. I was away and denied you of my comfort, yet you prayed for me to endure all hardships to complete this programme. I say I would forever be grateful and God bless you! ii University of Ghana http://ugspace.ug.edu.gh ACKNOWLEDGEMENTS I wish to express my sincere gratitude to the Almighty God for his numerous blessings, divine protection and direction throughout my studies. My profound gratitude also goes to Dr. Clement Akotsen- Mensah and Dr. Ken Okwae Fening, my supervisors for suggesting this topic and I appreciate their valuable criticisms, suggestions, corrections and support which have helped me greatly in preparing this dissertation. My special thanks also go to Mrs. Evelyn Opare, District Director of Agriculture, and my colleague staff of MoFA, Gomoa West District Assembly, for their support and advice. I am also grateful to the ARPPIS Coordinator, Dr. Rosina Kyerematen, and the thesis Coordinator, Dr. M.K. Billah of African Regional Post-graduate Programme in Insect Science (ARPPIS), Legon and all the lecturers for making my dream come true as an Entomologist. My deepest appreciation is extended to my wife, Helena Ezena, my daughters, Irene Ifeoma Adomah Ezena and Jessica Nkechi Dansowaa Ezena and my mum, Mad. Georgina Adomah and my entire family and Mr. Samuel Adu- Acheampong for their support, love, encouragement and prayers throughout the study. I also wish to express my sincere thanks to all friends and ARPPIS classmates especially Angelina Fathia Osabutey, Charles Adzim Amankwah, Derrick Asante and Owusu Fordjour Aidoo for their valuable contributions which sustained me throughout the course. I express my sincere appreciation to all FOHCREC staff especially Mr. C. Adu- Gyamfi (Technician) and Mr. Isaac Amoh and also the inhabitants of FOHCREC. I finally say a big thanks to Sampson Addae, Ruth Ansah, Musah, Attakora, Koby and all national service persons. iii University of Ghana http://ugspace.ug.edu.gh TABLE OF CONTENTS Content Page DECLARATION ................................................................................................................. i DEDICATION .................................................................................................................... ii ACKNOWLEDGEMENTS .............................................................................................. iii TABLE OF CONTENTS .................................................................................................. iv LIST OF TABLES .......................................................................................................... viii LIST OF FIGURES ............................................................................................................ x LIST OF PLATES ............................................................................................................. xi LIST OF ABBREVIATIONS........................................................................................... xii LIST OF APPENDICES................................................................................................. xiii ABSTRACT .................................................................................................................... xiv CHAPTER ONE ................................................................................................................. 1 1.0 GENERAL INTRODUCTION ............................................................................ 1 1.1 Background .......................................................................................................... 1 1.2 Problem statement ................................................................................................ 2 1.3 Justification .......................................................................................................... 3 1.4 OBJECTIVES ...................................................................................................... 6 1.4.1 Main objective .................................................................................................. 6 1.4.2 Specific objectives ............................................................................................ 6 CHAPTER TWO ................................................................................................................ 7 2.0 LITERATURE REVIEW ........................................................................................ 7 2.1 History of cabbage as an edible leafy vegetable .................................................. 7 2.2 Description and agronomy of the cabbage plant .................................................. 8 2.3 Cabbage production and their constraints in Ghana .......................................... 10 iv University of Ghana http://ugspace.ug.edu.gh 2.4 Nutritional and health benefits of cabbage ........................................................ 11 2.5 Cabbage production as a source of employment ............................................... 12 2.6 Diseases of cabbage ........................................................................................... 13 2.7 Insect pests and other arthropods ....................................................................... 14 2.7.1 Diamondback moth, Plutella xylostella (L.) ............................................... 15 2.7.2 Cabbage aphid, Brevicoryne brassicae (L.) ............................................... 22 2.7.3 Cabbage looper, Trichoplusia ni (Hṳber) ................................................... 25 2.7.4 Cabbage webworm, Hellula undalis (F.) .................................................... 25 2.7.5 Cabbage flea beetle, Phyllotreta spp. ......................................................... 25 2.7.6 Variegated grasshopper, Zonocerus variegatus (L.) ................................... 26 2.8 Management of cabbage pests ........................................................................... 26 2.8.1 Biological control ....................................................................................... 26 2.8.2 Host plant resistance ................................................................................... 28 2.8.3 Mating disruption using sex pheromones ................................................... 28 2.8.4 Insecticides ................................................................................................. 29 2.8.5 Cultural practices ........................................................................................ 33 2.9 Use of botanicals and their importance in pest management ............................ 34 2.10 Common plants used as botanicals .................................................................... 38 2.10.1 Siam weed, Chromolaena odorata (Asteraceae) ......................................... 38 2.11 Neem tree (Azadirachta indica A. Juss) ............................................................ 40 2.11.1 Importance of neem as botanicals ............................................................ 42 CHAPTER THREE .......................................................................................................... 44 3.0 MATERIALS AND METHODS ....................................................................... 44 3.1 Study location .................................................................................................... 44 3.2 Preparation of treatments ................................................................................... 44 3.2.1 Preparation of Chromolaena odorata leaf extracts .................................... 45 v University of Ghana http://ugspace.ug.edu.gh 3.2.2 Preparation of neem seed extracts .............................................................. 45 3.3 Field experiment ...............................................................................................
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