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Biological control of soil-dwelling insect pests in cocoa agroforests using CO2-emitting capsules co- formulated with entomopathogenic fungi FC Ambele orcid.org / 0000-0002-1624-2392 Thesis submitted in fulfilment of the requirements for the degree Doctor of Philosophy in Biology at the North-West University Promoter: Prof OO Babalola Co-promoter: Dr HB Bisseleua Daghela Co-supervisor: Dr S Ekesi Co-supervisor: Dr KS Akutse Graduation ceremony: April 2020 Student number: 28480694 01-02-2020 DEDICATION This thesis is dedicated to God Almighty for preserving my life after a ghastly motor accident I was involved in during this research work. It is also dedicated to my entire family, especially my lovely husband Anyame Nelson Ambia and kids, Anyame Shammah Azie and Anyame Shamita Amah for enduring the long period of my absence from home, and for their love and timeless support. iii ACKNOWLEDGEMENTS My deepest gratitude goes to God who provided all that was needed to complete this project and the program for which it was undertaken for. Throughout this entire study, He took care of everything that would have stopped me in my tracks and strengthened me even through my most difficult times. I recognize with great appreciation and gratitude my supervisors, Professor Olubukola O. Babalola, Drs. Hervé B. Bisseleua Daghela, Sunday Ekesi and Komivi S. Akutse for their academic guidance, support, constructive critisms and encouragement, and for accepting nothing less than excellence from me. I consider myself privileged to have learnt at the feet of such highly experienced persons. I am also particularly indebted to them for facilitating all the field activities whenever the need arose and mentoring me to discover my potential in conducting and interpretating research findings, as well as writing of manuscripts for publication. I express my sincere and wholehearted thanks to the International Centre of Insect Physiology and Ecology (icipe) which gave me this doctoral study opportunity through the African Regional Postgraduate Programme in Insect Science (ARPPIS), funded by the German Academic Exchange Service/Deutscher Akademischer Austauschdienst (DAAD). The Volkswagen Foundation, under the Funding Initiative Knowledge for Tomorrow-Cooperative Research Projects in sub-Saharan on Resources, their Dynamics, and Sustainability-Capacity Development in Comparative and Integrated Approaches provided research funding for which I am deeply indebted. I also appreciate all the support and advice of senior colleagues, especially Drs. Ngichop Caroline, Cham David, Samuel Adu Achaempong, Poumo Tchouassi, Tanga Mbi, Selpha Opisa, Sheila Agha, and all my colleagues at icipe who were extremely helpful in numerous ways to make my stay in Nairobi memorable both professionally and socially. I also want to say a big thank you to all my classmates and other colleagues, especially Mawuko Sokame, Abdullah Mkiga, Hilaire Kpongbe, Abdelmutalab Gesmalla, ii Diabate Seydou, Olabimpe Olaide, Akua Konadu, Pamela Ochungo, Shaphan Yong, Steve Baleba, Kieran Yisa and Mawufe Agbodzavu for their friendship, wonderful time, and fun moments we shared while in icipe. Special thanks also go to the staff of icipe Capacity Building, Dr. Robert Skilton, Vivian Atieno, Mama Maggy Ochanda, Esther Ndung’u, and to the entire finance team of icipe for ensuring I did my work smoothly. I am also indebted to the technical staff of icipe Athropod Pathology Unit (APU), notably Sospeter Wafula, Jane Wanjiru and Ombura Odhiambo for their laboratory and other technical assistance. I am grateful to Drs. Didier Begoude, Director of Biotechnology laboratory and Ndzana A., Director of the Entomology laboratory of the Institute for Agricultural Research for Development (IRAD), Nkolbisson, Yaoundé for hosting me and all the team of the Biotechnology and Entomology laboratories of IRAD, especially Christian Djuideu, Enanga Veronica Ndive, Kapeua Miraine, Owona Alexis for their assistance during this study. I want to say a special thank you to Prof. Ateba Collins, Dr. Ayansina Ayangbenro and all the students of Microbial Biotechnology Group of NWU South Africa-Mafikeng campus. My profound gratitude also goes out to all DAAD alumni members in Cameroon, especially Profs. Nukenine Elias and Fokam Eric for their advice and assistance. I am also grateful to all the managers and workers of all the farms where I conducted my field work in Cameroon. There are no words to express my gratitude and thanks to my beloved mother Ngwe Grace Azie, father Ambele Patrick Azie, aunts Akande Sarah and Ambia Veronica as well as my other family members who provide unending inspiration and for supporting me spiritually throughout this research and my life in general. iii TABLE OF CONTENTS DECLARATION AND APPROVAL ............................................................................................ ii DEDICATION ............................................................................................................................... iii ACKNOWLEDGEMENTS ............................................................................................................ ii TABLE OF CONTENTS ................................................................................................................ ii LIST OF TABLES ....................................................................................................................... viii LIST OF FIGURES ....................................................................................................................... ix GENERAL ABSTRACT ................................................................................................................ ii LIST OF PUBLICATIONS ............................................................................................................ ii 1 CHAPTER ONE: GENERAL INTRODUCTION .................................................................. 1 1.1 Background information .................................................................................................. 1 1.2 Problem statement ............................................................................................................ 4 1.3 Justification of the study .................................................................................................. 5 1.4 Objectives of the study ..................................................................................................... 6 1.4.1 General objective ...................................................................................................... 6 1.4.2 Specific objectives .................................................................................................... 6 1.5 Hypotheses ............................................................................................................................ 7 References ................................................................................................................................... 8 2 CHAPTER TWO: LITERATURE REVIEW........................................................................ 12 2.1 Cocoa .............................................................................................................................. 12 2.1.1 Origin of cocoa ............................................................................................................. 12 2.1.2 Cocoa production in Africa ..................................................................................... 12 2.1.3 Importance of cocoa ................................................................................................ 13 2.1.4 Cocoa agroforestry and importance of agroforestry products ................................ 14 2.2 Insect pests of cocoa ....................................................................................................... 15 2.2.1 Above-ground pests of cocoa ....................................................................................... 15 2.2.2 Below-ground or soil dwelling insect pests of cocoa ............................................. 15 2.3 Termite ecology.............................................................................................................. 16 2.4 Termite taxonomy and diversity .................................................................................... 17 ii 2.5 Termite life types ........................................................................................................... 18 2.5.1 Nesting types ........................................................................................................... 18 2.5.2 Trophic groups (feeding groups) ............................................................................ 18 2.6 Termite biology .............................................................................................................. 19 2.6.1 Colony structure and life cycle ............................................................................... 19 2.6.1.1 Worker caste ........................................................................................................ 20 2.6.1.2 Soldier caste ........................................................................................................ 20 2.6.1.3 Reproductive castes ............................................................................................. 21 2.7 Management practices for termite pests .............................................................................. 22 2.7.1 Location of host plants by termites .................................................................................