MODELLING SPATIAL DISTRIBUTION OF TSETSE (DIPTERA: GLOSSINIDAE) IN MASOKA AREA, AN UNEXPLORED PART OF MBIRE DISTRICT, ZIMBABWE BY GERALD CHIKOWORE A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in Tropical Entomology University of Zimbabwe Faculty of Science Department of Biological Sciences May 2016 DECLARATION I hereby declare that this thesis is my own original work and has not been submitted for a degree in any other university. ………………………………………… ……………………………… Gerald Chikowore Date We as supervisors confirm that the work reported in this thesis was carried out by the candidate under our supervision. The thesis was examined and we approved it for final submission. ………………………………………... ………………………………. Dr. P. Chinwada Date ………………………………………… ……………………………… Dr. M. Zimba Date ii DEDICATION This work is dedicated to my wife, Tinotenda and daughter Tinevimbo. iii ACKNOWLEDGEMENTS I would like to extend my gratitude to my academic supervisors Drs P. Chinwada, M. Zimba, and L. Guerrini for their immense contribution and guidance in the conduct of this research. Their expertise and wisdom steered this work to its completion. I am also indebted to the Division of Tsetse Control for allowing me to utilise their facilities during the study. Thanks are also extended to Tsetse Control Mashumbi field staff, Mr S. Katumba, Mr F. Hlekwayo, Mr S. Bangajena, Mr R. Joko, CAMPFIRE warden in Masoka, Mr M. Fakero and CIRAD member, Mr N. Chiweshe, for assisting in the collection of tsetse samples. Their endurance and hard work helped me cover as much of the Masoka area as possible in the simmering heat. Mr L. Nyakupinda patiently assisted in the analysis of data and I am grateful to him. This work was conducted within the framework of the Research Platform “Production and Conservation in Partnership” (www.rp-pcp.org). The European Union and African Carribbean Pacific Group of states funded this research through the GeosAf project and I would like to acknowledge their contribution which made it possible to conduct all the fieldwork. The GeosAf project, implemented by CIRAD also imparted geomatic techniques which were essential in the spatial analysis of data in this project. Satellite images used in this research were provided by SPOT ISIS-CNES. iv ABBREVIATIONS AND ACRONYMS ACP African Caribbean Pacific Group of States AUC Area Under the Curve AU-IBAR African Union Inter-African Bureau for Animal Resources AVHRR Advanced Very High Resolution Radiometer DLST Day Land Surface Temperature EU European Union FAO Food and Agriculture Organisation of the United Nations GeosAf Geomatic Tools Transferred to Animal Health Services in Southern Africa GIS Geographic Information Systems GPS Global Positioning System IAEA International Atomic Energy Agency ISIS-CNES Incitation à l'utilisation Scientifique des Images SPOT - Centre National d'études Spatiales MaxEnt Maximum Entropy MIR Mid Infra-Red MODIS Moderate-resolution Imaging Spectroradiometer NASA National Aeronautics and Space Administration NDVI Normalized Difference Vegetation Index NLST Night Land Surface Temperature NOAA National Oceanic and Atmospheric Administration PATTEC Pan-African Tsetse and Trypanosomiasis Eradication Campaign ROC Receiver Operated Characteristics RP-PCP Research Platform-Production and Conservation in Partnership SPOT Satellite Pour l’Observation de la Terre WHO World Health Organisation v ABSTRACT A study was conducted from March 2015 to December 2015 in order to model the distribution of two savannah species of tsetse (Glossina sensu stricto), Glossina morsitans morsitans and G. pallidipes in the Masoka area of the Mid-Zambezi valley in Zimbabwe. Two approaches were used. The first approach sought to model the probability of presence of both species in areas which were sampled but recorded zero tsetse catches using trap efficiency, sampling effort and suitable habitat cover. A probability threshold of 0.05 was used to distinguish areas which could be potentially infested from those that had low chances of tsetse occurrence. The resultant probability model pointed to an area of 104 km2 in size where G. m. morsitans could possibly be present (P > 0.05) whilst all areas which did not record G. pallidipes had a low probability of presence for the species (P < 0.05). This study showed that there was a high probability of tsetse presence in areas where the habitat was less degraded and low probability in settled areas where suitable tsetse habitat has been disturbed due to agricultural activities. The probability model therefore has the potential to optimize vector control strategies by streamlining areas of intervention. The second model was a predictive one built using tsetse presence-only data and climatic and environmental covariates. The model had an Area Under the Curve (AUC) of 0.80 for G. m. morsitans and 0.94 for G. pallidipes, indicating that the ability of the model to predict suitable tsetse habitat in the Masoka area was better than random (AUC = 0.5). Glossina morsitans morsitans occurrence was positively correlated to Normalised Difference Vegetation Index (NDVI), riverine forest and mopane woodlands whilst crop lands and temperature indices exhibited a strong negative correlation with its occurrence. Glossina pallidipes, on the other hand, had extremely specialised habitat requirements and was positively correlated to riverine forest. The species also had a positive correlation with NDVI but a negative correlation with mopane woodland. vi TABLE OF CONTENTS DECLARATION ....................................................................................................................... ii DEDICATION ......................................................................................................................... iii ACKNOWLEDGEMENTS ...................................................................................................... iv ABBREVIATIONS AND ACRONYMS .................................................................................. v ABSTRACT .............................................................................................................................. vi TABLE OF CONTENTS ......................................................................................................... vii LIST OF TABLES .................................................................................................................... ix LIST OF FIGURES ................................................................................................................... x CHAPTER 1 .............................................................................................................................. 1 INTRODUCTION .................................................................................................................. 1 1.1 Overview ...................................................................................................................... 1 1.2 Justification of the Study .............................................................................................. 2 1.3 Objectives ..................................................................................................................... 4 1.4 Hypotheses.................................................................................................................... 4 CHAPTER 2 .............................................................................................................................. 5 LITERATURE REVIEW ....................................................................................................... 5 2.1 Economic Importance of Tsetse and Trypanosomiasis ................................................ 5 2.2 Tsetse Taxonomy .......................................................................................................... 6 2.3 Tsetse Distribution in Zimbabwe ................................................................................. 7 2.4 Climatic and Environmental Requirements of Tsetse .................................................. 8 2.5 Host Preferences for Tsetse ........................................................................................ 10 2.6 Tsetse Surveillance ..................................................................................................... 12 2. 7 Species Distribution Models ...................................................................................... 14 2.8 Applications of Models in Tsetse and Trypanosomiasis Management ...................... 17 CHAPTER 3 ............................................................................................................................ 18 MATERIALS AND METHODS ......................................................................................... 18 3.1 The Study Area ........................................................................................................... 18 CHAPTER 4 ............................................................................................................................ 20 Probability of Tsetse Occurrence Despite a Sequence of Zero Catches .............................. 20 4.1 Introduction ................................................................................................................ 20 4.2 Materials and Methods ............................................................................................... 20 vii 4.3.1 Surveys ...................................................................................................................