FORAGING ACTIVITY AND CONTROL OF TERMITES IN WESTERN ETHIOPIA By ABDURAHMAN ABDULAHI A thesis submitted for the degree of Doctor of Philosophy of the University of London and for the Diploma of Imperial College Department of Pure and Applied Biology Imperial College of Science, Technology and Medicine Silwood Park Ascot February 1990 ABSTRACT The termite species identified as crop pests in western Ethiopia belong to the subfamily Macrotermitinae and to the genera Macrotermes, Microtermes, Odontotermes and Pseudacanthotermes; however, only Macrotermes was economically important. Macrotermes subhyalinus (Rambur) foraged throughout the year while the main activity of Microtermes was during the rainy season and that of Pseudacanthotermes during the dry season. During the wet season Microtermes foraging activity occurred throughout the day and night while the activity of Pseudacanthotermes was restricted to certain specific periods of the day or night both during dry and wet seasons. Studies on Microtermes showed no relationship between the number of plants attacked and yields of maize and sunflower; peppers on farmers fields were not infested and yield losses were principally in haricot beans, and ranged from 4.5 to 1 2 .8%. Simulation of Macrotermes damage in maize showed that yield loss depends on the extent of stand reduction and the- growth stage of the crop. Stand reduction at the early stage had no effect until more than 3 0% of the plants were removed. The yield reduction of 40 per cent was obtained when 45% of the plant population was removed at the tasselling stage. 2 The incidence of Microtermes attack was unaffected by applying fertilizer. Doubling the recommended sowing rate reduced maize yield by about 40%. Seed treatment with chlorpyrifos, isofenphos or aldrin or furrow treatment before sowing or a combination of both gave no protection against Microtermes or Macrotermes. The application of chlorpyrifos at the rate of 20.2 g a.i. per mound effectively killed Macrotermes colonies, but the use of diazinon and removing the queen from the nest gave only partial success. No significant yield difference was found in tef between areas where mounds were treated and untreated due to the presence of young colonies that have not yet built mounds. Studies including morphometric analysis on Macrotermes in western Ethiopia indicated that two distinct populations exist with different mound ■ building behaviour. Whether these differences indicate different species or not is not yet known. There was no evidence that crop damage is due to the removal of natural vegetation. 3 Table of Contents Page Title page 1 Abstract 2 Table of Contents 4 List of Figures 8 List of Plates 11 List of Tables 11 List of Appendices 16 Chapter One: General Introduction 20 1.1 Characteristics of Termites 20 1.2 Classification 22 1.3 Geographical Distribution 24 1.4 Biology of Termites 26 1.5 Economic Significance 29 1.6 Termite Problem in Western Ethiopia 38 1.7 Objectives of the Study 43 Chapter Two: Study Sites 45 2.1 Location 45 2.2 Geology 47 2.3 Climate 48 2.4 Soils 50 2.5 Natural Vegetation 50 2.6 Crop Production 52 Chapter Three: Termites of Agricultural Importance in Western Ethiopia 55 4 3.1 Introduction 55 3.2 Materials and Methods 60 3.3 Results and Discussion 63 3.3.1 Termite Species 63 3.3.2 Flight of Alates 74 3.3.3 Abundance of Macrotermes Mounds and Foraging Holes 76 Chapter 4 Periodic Variations in Foraging Activity 80 4.1 Introduction 80 4.2 Materials and Methods 87 4.2.1 Seasonal Variations in Foraging Activity 87 4.2.2 Diurnal Variations in Foraging Activity 93 4.2.3 Seasonal Feeding Habits 93 4.3 Results and Discussion 94 4.3.1 Seasonal Foraging Activity 94 4.3.2 Spatial Variations in Foraging Activity 115 4.3.3 Foraging Activity Variations Between 1987 and 1988 116 4.3.4 Foraging Population of Microtermes 111 4.3.5 Diurnal Foraging Activity 119 4.3.6 Seasonal Feeding Habits 123 Chapter Five: Crop Damage and Yield Loss Assessment 127 5.1 Introduction 127 5.2 Materials and Methods 136 5 5.2.1 Microtermes Loss Assessment 136 5.2.2 Simulation of Macrotermes Damage 139 5.3 Results and Discussion 143 5.3.1 Microtermes Attack in Maize 143 5.3.2 Microtermes Damage Survey in Pepper 146 5.3.3 Microtermes Damage in Haricot Beans 148 5.3.4 Microtermes Attack in Sunflower 150 5.3.5 Simulation of Macrotermes Damage 152 Chapter Six: Termite Control in Crops 158 6.1 Introduction 158 6.2 Materials and Methods 177 6.2.1 Termite Control in Maize 177 6.2.2 Termite Control in Tef 181 6.2.3 Termite Colony Destruction 182 6.2.4 Evaluation of Mound Poisoning 183 6.3 Results and Discussion 184 6.3.1 Effect of Insecticides and Methods of Application in Maize seed Germination 184 6.3.2 Microtermes : Effectiveness of Control Methods 185 6.3.3 Macrotermes : Effectiveness of Control Methods 191 6.3.4 Period of Macrotermes Attack 192 6.3.5 Effect of Insecticides in Foraging Activity 195 6.3.6 Effect of Different Termite Control 6 Methods in Maize yield 198 6.3.7 Effect of Heptachlor in Tef Yield 201 6.3.8 Termite Colony Destruction 204 6.3.9 Effect of Mound Poisoning in Tef Yield 205 6.3.10 Effect of Mound Poisoning in Colony Development 207 Chapter Seven: Variations in Pest Status of Macrotermes 209 7.1 Introduction 209 7.2 Materials and Methods 215 7.2.1 Removal of Natural Vegetation 215 7.2.2 Termite Population 215 7.3 Results and Discussion 217 7.3.1 Effect of Removing Natural Vegetation 217 7.3.2 Morphometric Analysis 222 7.3.3 Differences in Mound structure and Size 228 Chapter Eight: Summary 231 Conclusion 236 Acknowledgements 238 References 240 Appendices 260 7 List of Figures Page Figure 2. 1 Location of study sites in western Ethiopia 46 Figure 4. 1 Relationship between seasonal foraging activities of Microtermes nr. vadschaggae, M . aethiopicus and Pseudacanthotermes militaris and monthly rainfall on woodland at Sasiga 96 Figure 4 2 Relationship between seasonal foraging activities of Microtermes nr. vadschaggae and M. aethiopicus and monthly rainfall on fallow land at Ghimbi-1 97 Figure 4 .3 Relationship between foraging activities of Microtermes nr. vadschaggae, M. aethiopicus and Pseudacanthotermes militaris and monthly rainfall on afforestation site at Mendi 98 Figure 4 .4 Relationship between foraging activities of Microtermes nr. vadschaggae and Macrotermes subhyalinus and monthly rainfall on cultivated land at Ghimbi-2 99 Figure 4 .5 Relationship between foraging activities of Microtermes nr. vadschaggae and monthly rainfall on cultivated land at Nedjo 10 0 8 Figure 4.6 Relationship between foraging activities of Microtermes nr. vadschagge and M. aethiopicus and monthly rainfall on cultivated land at Didesa 101 Figure 4 .7 Relationship between foraging activities of Microtermes nr. vadschaggae and monthly rainfall on cultivated land at Bako Agricultural Research Centre 102 Figure .8 Relationship between seasonal foraging activities of Microtermes nr. vadschaggae and Pseudacanthotermes militaris and monthly rainfall on cultivated land at Sasiga 103 Figure .9 Relationship between seasonal foraging activities of Microtermes nr. vadschaggae and monthly•rainfall on cultivated land at Ghimbi-1 104 Figure .10 Relationship between foraging activities of Microtermes nr. vadschaggae and Macrotermes subhyalinus and monthly rainfall on cultivated land at Mendi 105 Figure .11 Relationship between foraging activities of Microtermes nr. vadschaggae and Macrotermes subhyalinus and monthly rainfall on cultivated land at Henna 106 Figure .12 Relationship between foraging activities of Microtermes nr. vadschaggae and 9 Macrotermes subhyalinus and monthly rainfall on cultivated land at Ghimbi-2 107 Figure 4.13 Relationship between Microtermes nr. vadschaggae foraging activity and total monthly rainfall 109 Figure 4.14 Relationship between Microtermes aethiopicus foraging activity and total monthly rainfall 110 Figure 4.15 Relationship between Pseudacanthotermes militaris foraging activity and total monthly rainfall 114 Figure 4.16 Diurnal foraging activity of Microtermes nr. vadschaggae and Pseudacanthotermes militaris on bushland at Sasiga 120 Figure 4.17 Diurnal foraging activity of Microtermes nr. vadschaggae on fallow land at Ghimbi-1 121 Figure 5.1 The location of maize plants removed in planting rows 142 Figure 5.2 Relationship between percentage of plants attacked by Microtermes and yield loss in haricot beans 149 Figure 5.3 Relationship between stand reduction and yield compensation in maize 155 Figure 6.1 Maize plants cut by Macrotermes subhyalinus on untreated plots at different times after emergence 193 Figure 7.1 Land use/land cover map of Mendi - 1957 218 10 Figure 7.2 Land use/land cover map of Mendi - 1980 219 Figure 7.3 Land use/land cover map of Ziway - 1967 220 Figure 7.4 Land use/land cover map of Ziway - 1971 221 Figure 7.5 Frequency distribution of major soldier sizes 226 List of Plates Page Plate 4.1 Wood baits used to monitor foraging activity 89 Plate 4.2 Wood baits attacked by Microtermes 90 Plate 4.3 Wood baits attacked by Macrotermes 91 Plate 6.1 Macrotermes mound flooding in Didesa 159 Plate 6.2 Macrotermes attack in tef 203 Plate 7.1 Macrotermes mounds in Mendi and Ziway 230 List of Tables Page Table 1.1 Macrotermes damage on crops and young trees in different countries in Africa 32 Table 1.2 Microtermes damage in crops in different countries in Africa 33 Table 1.3 Odontotermes damage on crops and forestry seedlings in different parts of Africa 34 Table 1.4 Pseudacanthotermes, Ancistrotermes and Allodontermes damage to crops in