University of Ghana http://ugspace.ug.edu.gh EVALUATION OF TWO TRAP TYPES AND TWO ATTRACTANTS FOR MANGO STONE WEEVIL Sternochetus mangiferae (F) (COLEOPTERA: CURCULIONIDAE) IN THREE DISTRICTS IN SOUTHERN GHANA BY ANDERSON ROGER SIGISMUND (10088929) (BSc. ZOOLOGY: UNIVERSITY OF GHANA, LEGON) THIS THESIS IS SUBMITTED TO THE UNIVERSITY OF GHANA, LEGON IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF MASTER OF PHILOSOPHY IN ENTOMOLOGY DEGREE AFRICAN REGIONAL POSTGRADUATE PROGRAMME IN INSECT SCIENCE (ARPPIS)*, UNIVERSITY OF GHANA, LEGON JULY, 2015 *JOINT INTER-FACULTY INTERNATIONAL PROGRAMME FOR THE TRAINING OF ENTOMOLOGISTS IN WEST AFRICA. COLLABORATING DEPARTMENTS: DEPARTMENT OF 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 I hereby declare that this research was undertaken by me, Roger Sigismund Anderson, in fulfillment of the award of Master of Philosophy degree in Entomology at the African Regional Postgraduate Programme in Insect Science (ARPPIS), College of Basic and Applied Sciences, University of Ghana, Legon. All references to other people’s work have been duly acknowledged and this work has not been presented in part or in full anywhere for any other degree. …………………………………………………………………… ANDERSON ROGER SIGISMUND (STUDENT) …………………………………………………………………….. Dr. CLEMENT AKOTSEN-MENSAH (SUPERVISOR) …………………………………………………………………….. Prof. KWAME AFREH-NUAMAH (SUPERVISOR) …………………………………………………………………….. Dr. Mrs. DORCAS OSEI-SAFO (SUPERVISOR) ……………………………………………………………………… Dr. ROSINA KYEREMATEN (CO-ORDINATOR ARPPIS) i    University of Ghana http://ugspace.ug.edu.gh   DEDICATION I dedicate this work to God Almighty for His tremendous grace, mercy and favor. Also to my parents, Mr. and Mrs. Anderson and my siblings Patricia, Glenda, Isabella, Aloysia and Balthassar for their immense financial and spiritual support throughout this 2-year period. I love you all. ii    University of Ghana http://ugspace.ug.edu.gh   ACKNOWLEDGEMENT My sincere gratitude goes to my supervisors, Dr. Clement Akotsen-Mensah, Prof. Kwame Afreh- Nuamah and Dr. Mrs. Dorcas Osei-Safo for their tremendous efforts, patience, advice, guidance and wonderful contributions towards this work. I express my profound gratitude to the Coordinator of African Regional Postgraduate Programme in Insect Sciences (ARPPIS), Dr. Rosina Kyerematen for her motherly care, prayers, advice and support. To all my lecturers especially Dr. Maxwell Billah, I say I am grateful to you for the meticulous training you provided throughout my programme. I am grateful to Mr. Jonathan Kwame Adabeng of Samano Farms, Mr. Sampson K. Amanor of Hydrotec Farms and Mr. Felix Siekang of Bismark Adu Farms for granting me permission to carry out this research on their mango farms. Again, my appreciation also goes to Mr. Victor Avah of the Ministry of Food and Agriculture and the entire Mango farmers Association of Yilo Krobo, Manya Krobo and Shai Osudoku districts for their immense contribution towards this work. I am highly indebted to my best friend Robert Ebow McEwan and my brother Prince Peter Acquah for their encouragement, financial and spiritual support. My appreciation also goes to all my friends especially Daniel Acquah-Lamptey, Derrick Asante, Kwame Adomako Asiama, Kwame Wadieh, Jeremiah Kweku Tweneboah, Hettie Boafo and Dorcas Ofosu-Budu for their intellectual, physical and moral support during this research. I am highly indebted to my siblings and parents for their support and prayers throughout my education. Above all, I am thankful to the Almighty God for bringing me this far in my iii    University of Ghana http://ugspace.ug.edu.gh   education. To all my course mates Dorcas Atibilla, Lami Jinatu, Ruth Buba Bala, Comfort Aku Oseifuah, Nnenna Ononye, Michelline Nintonou, Chia Shaphan Yong, Dickson Nimlin Gabun, Okeke Peter, and Franklin Ayisi, I say a big thank you. You have all proven beyond all reasonable doubts that you are indeed wonderful. Finally, I am also thankful to the Office of Research Innovation and Development (ORID), University of Ghana for the financial support throughout this research. iv    University of Ghana http://ugspace.ug.edu.gh   ABSTRACT The Black pyramid and Circle traps were evaluated with single and double combinations of gas chromatography grade of benzaldehyde (BZ) and essential oil (EO) obtained from the mango blossom to determine their performance in attracting the mango stone weevil in three commercial mango orchards located at Ayikuma, Kpong and Somanya all in Southern Ghana. Eight trap and lure treatment combinations consisting of (Pyramid trap only, Pyramid trap + BZ, Pyramid trap + EO, Pyramid trap + BZ + EO, Circle trap only, Circle trap + BZ, Circle trap + EO and Circle trap + BZ + EO) were evaluated in a randomized complete block design. The number of mango weevils captured during each week of sampling was used as a measure for trap effectiveness. A total of 14 mango stone weevils were recorded by the various traps and lure combinations in all the three study sites. The Black pyramid trap captured more of the stone weevils (about 6-fold) compared to the Circle traps. The ANOVA results showed that there were significant differences among the locations, trap type, lure type and the interaction between trap type and lure type. The interaction however, among location*trap type, location*lure type and location*trap type*lure type were not significant. The trap performance was not improved by addition of the attractants. Stone weevil damage ranged between 54.5 and 92.9 % at Kpong and Ayikuma respectively. The effect of temperature and humidity on trap and lure performance could not be determined in this study due to zero trap capture during the major mango fruiting season. Intensive spraying of the orchards, low stone weevil populations, high concentrations of host plant volatiles released in the orchards, the possibility of the stone weevils escaping from the v    University of Ghana http://ugspace.ug.edu.gh   pyramid traps, and the fact that the essential oils used in this work were crude extracts; are some of the reasons which could have accounted for the low trap captures. vi    University of Ghana http://ugspace.ug.edu.gh   TABLE OF CONTENTS Contents CHAPTER ONE ............................................................................................................................. 1 GENERAL INTRODUCTION ................................................................................................... 1 1.1. Background .......................................................................................................................... 1 1.2. Justification .......................................................................................................................... 5 1.3. Research Objectives ............................................................................................................. 7 1.3.1. Main Objective .................................................................................................................. 7 1.4. Specific Objectives ............................................................................................................... 7 CHAPTER TWO ............................................................................................................................ 8 LITERATURE REVIEW ............................................................................................................ 8 2.1. The Mango Crop .................................................................................................................. 8 2.2. Mango Varieties Propagated in Ghana ................................................................................. 9 2.2.1. ‘Keitt’ Mango .................................................................................................................... 9 2.2.2 ‘Kent’ Mango ................................................................................................................... 10 2.2.3. ‘Tommy Atkins’ Mango.................................................................................................. 10 2.2.4. ‘Haden’ Mango ............................................................................................................... 10 2.3. Mango Production and Distribution ................................................................................... 11 2.4. Economic Importance of Mango ........................................................................................ 14 2.5. Constraints to Mango Production in Ghana ....................................................................... 15 2.6. The Mango Stone Weevil, Sternochetus mangiferae (F) ................................................... 16 2.6.1. Taxonomy and Distribution of the Mango Stone Weevil, Sternochetus mangiferae (F) 16 2.6.2. The Biology of the Mango Stone Weevil ........................................................................ 18 2.6.3. Host and Mechanism of Host Selection of the Stone Weevil ......................................... 20 2.6.4 General Behaviour of Mango Stone Weevil .................................................................... 21 2.6.5. Economic Importance of Stone Weevil Damage ............................................................ 22 2.6.6. Effect of Some Environmental Factors on the Stone Weevil .......................................... 24 2.6.7. Pest Management Strategies ............................................................................................ 25 vii    University of Ghana http://ugspace.ug.edu.gh   2.6.7.1. Host Plant Resistance ................................................................................................... 25 2.6.7.2. Cultural Control........................................................................................................... 26 2.6.7.3. The Use of Semiochemicals For Monitoring ............................................................... 26 2.6.7.4. Trapping ....................................................................................................................... 27 2.6.7.4.1. Pyramid Traps ........................................................................................................... 28 2.6.7.4.2. Circle Traps ............................................................................................................... 31 2.6.7.5. Chemical Control ......................................................................................................... 31 2.6.7.6. Quarantine and Phytosanitory Measures ...................................................................... 33 2.6.7.7. Biological Control ........................................................................................................ 34 CHAPTER THREE ...................................................................................................................... 36 METHODOLOGY .................................................................................................................... 36 3.1. General Procedures ............................................................................................................ 36 3.1.1. Study Areas ..................................................................................................................... 36 3.1.2. Description of the Study Areas ....................................................................................... 36 3.1.3. Description of the Study Farms ....................................................................................... 38 3.2. Field Evaluation of Traps and Lures .................................................................................. 39 3.2.2. Trap Deployment............................................................................................................. 39 3.2.3. Lure Treatments .............................................................................................................. 42 3.3. Effect of Air Temperature and Relative Humidity on Trap and Lure Performance .......... 43 3.4. Release Rate of Lures ......................................................................................................... 44 3.5. Fruit Damage Assessment During the Major and Minor Mango Fruiting Season ............. 45 3.2 Statistical Analyses ............................................................................................................. 48 CHAPTER FOUR ......................................................................................................................... 49 RESULTS.................................................................................................................................. 49 4.1. General Trap Performance ................................................................................................. 49 4.2. Trap and Lure Performance ................................................................................................ 50 4.2.1. General Performance of Traps Across the Study Locations ........................................... 50 4.2.2. Performance of Traps in Combination with Four Treatments ........................................ 52 viii    University of Ghana http://ugspace.ug.edu.gh   4.2.3. Performance of the Individual Trap Types in All the Three Study Locations ................ 54 4.2.4. Performance of Treatments Across the Study Locations ................................................ 56 4.3. Average Weekly Temperature and Relative Humidity During the Major Mango Fruiting Season in Somanya .................................................................................................................... 58 4.4. Release Rates of Lures ....................................................................................................... 59 4.5. Fruit Damage Assessment .................................................................................................. 60 CHAPTER FIVE .......................................................................................................................... 62 DISCUSSION ........................................................................................................................... 62 5.1 Trap and Lure Performance ................................................................................................. 62 5.2. Fruit Damage Assessment During the Major and Minor Mango Fruiting Season ............. 69 5.3. Effect of Temperature and Relative Humidity on Trap and Lure Performance ................. 71 5.4. Release Rates of Lures ....................................................................................................... 73 CHAPTER SIX ............................................................................................................................. 74 CONCLUSIONS AND RECOMMENDATIONS .................................................................... 74 6.1. Conclusions ........................................................................................................................ 74 6.2. Recommendations .............................................................................................................. 75 REFERENCES ............................................................................................................................. 76 ix    University of Ghana http://ugspace.ug.edu.gh   LIST OF FIGURES  FIGURE 1. GEOGRAPHICAL DISTRIBUTION OF THE MANGO STONE WEEVIL IN AFRICA (RED MARKED)................................................................................................... 18 FIGURE 2. MAP SHOWING THE SHAI OSUDOKU, MANYA AND YILO KROBO DISTRICTS WHERE THE STUDY WAS CONDUCTED ................................................. 38 FIGURE 3. A GRAPH COMPARING THE MEAN TRAP CATCHES BETWEEN CIRCLE AND PYRAMID TRAPS USED IN AYIKUMA. ................................................................ 50 FIGURE 4. A GRAPH COMPARING THE MEAN TRAP CATCHES BETWEEN THE CIRCLE AND PYRAMID TRAPS IN KPONG. ................................................................. 51 FIGURE 5. A GRAPH SHOWING MEAN (± SE) TRAP CATCHES FOR THE CIRCLE TRAP IN COMBINATION WITH THE FOUR TREATMENTS IN ALL THE STUDY AREAS. ............................................................................................................................................... 52 FIGURE 6. A GRAPH SHOWING THE MEAN TRAP CATCHES FOR THE PYRAMID TRAP IN COMBINATION WITH ALL THE FOUR TREATMENTS IN ALL THE STUDY AREAS. ................................................................................................................... 53 FIGURE 7. A GRAPH SHOWING THE MEAN (± SE) TRAP CATCHES OF THE CIRCLE TRAP IN ALL THE THREE STUDY AREAS .................................................................... 54 FIGURE 8. A GRAPH SHOWING THE MEAN (± SE) TRAP CATCHES OF THE PYRAMID TRAP IN ALL THE THREE STUDY AREAS. ................................................................... 55 FIGURE 9. A GRAPH SHOWING MEAN (± SE) TRAP CATCHES OF THE FOUR TREATMENTS USED IN AYIKUMA. ............................................................................... 56 FIGURE 10. A GRAPH SHOWING MEAN (± SE) TRAP CATCHES OF THE FOUR TREATMENTS USED IN KPONG. .................................................................................... 57 x    University of Ghana http://ugspace.ug.edu.gh   FIGURE 11. A GRAPH SHOWING THE WEEKLY AVERAGE TEMPERATURE AND RELATIVE HUMIDITY DURING THE MAJOR MANGO FRUITING SEASON .......... 58 FIGURE 12. THE MEAN PERCENT DAMAGE OF MANGO FRUITS IN ALL THE THREE STUDY AREAS DURING THE MAJOR AND MINOR MANGO FRUITING SEASON. ............................................................................................................................................... 60 FIGURE 13. A GRAPH SHOWING THE SEASONAL OCCURRENCE OF THE MANGO STONE WEEVIL IN ALL THE STUDY AREAS DURING THE 2014 MANGO FRUITING SEASON ............................................................................................................ 61 xi    University of Ghana http://ugspace.ug.edu.gh   LIST OF PLATES PLATE 1. LIFE CYCLE OF THE MANGO STONE WEEVIL ................................................ 20 PLATE 2. TYPES/STAGES OF MANGO FRUIT DAMAGE BY THE STONE WEEVIL ...... 23 PLATE 3. THE BLACK (LEFT) AND YELLOW (RIGHT) PYRAMID TRAPS IN A MANGO AND PEACH ORCHARDS RESPECTIVELY.................................................................... 29 PLATE 4. A MODIFIED CIRCLE TRAP TIED WITH A MASKING TAPE IN A MANGO ORCHARD IN SOUTHERN GHANA ................................................................................. 30 PLATE 5. PEGGING (LEFT) AND PLACEMENT (RIGHT) OF THE BLACK PYRAMID TRAPS IN THE FIELD ........................................................................................................ 40 PLATE 6. CIRCLE TRAP (LEFT) WITH A LURE AND (RIGHT) WITHOUT A LURE DEPLOYED IN THE FIELD. RED ARROW INDICATES HOW WEEVILS ENTER THE TRAP ..................................................................................................................................... 41 PLATE 7. EXTRACTION (COLD PERCOLATION) OF ESSENTIAL OILS .......................... 42 PLATE 8. AFTER EXTRACTION ............................................................................................. 43 PLATE 9. DATA LOGGER PLACED IN ONE OF THE MANGO ORCHARDS WHERE THE STUDY WAS CONDUCTED .............................................................................................. 44 PLATE 10. CONTAINERS USED FOR THE RELEASE RATE OF EO AND BZ................... 45 PLATE 11. FRUIT CUTTING, SEED OPENING AND CHECKING FOR MSW IN SEED.... 46 PLATE 12. MSW LARVAE (ARROWED) IN A MATURED FRUIT ...................................... 46 PLATE 13. ADULT (BLACK) AND PUPA (WHITE) IN AN IMMATURE MANGO FRUIT 47 xii    University of Ghana http://ugspace.ug.edu.gh   LIST OF TABLES TABLE 1. TOP TEN MANGO PRODUCING COUNTRIES IN THE WORLD ....................... 12 TABLE 2. MANGO PRODUCTION (IN TONS) IN 13 WEST AFRICAN COUNTRIES FROM 2009-2011 .............................................................................................................................. 13 TABLE 3. DESCRIPTION OF THE PHENOLOGICAL STAGES OF THE MANGO CROP FROM JULY 2014-JUNE 2015 ............................................................................................ 47 TABLE 4. RELEASE RATES OF THE BENZALDEHYDE AND ESSENTIAL OILS UNDER FIELD (ONLY PYRAMID TRAP) AND LABORATORY CONDITIONS ....................... 59 xiii    University of Ghana http://ugspace.ug.edu.gh   LIST OF ABBREVIATIONS ARPPIS African Regional Postgraduate Program in Insect Science CABI Centre for Agriculture and Biosciences International EPPO European and Mediterranean Plant Protection Organization EU European Union FAO Food and Agricultural Organization FAOSTAT Food and Agricultural Organization Corporate Statistical Data Base GEPC Ghana Export Promotion Council GlobalGAP Global Good Agricultural Practices ICRAF International Centre for Research in Agro Forestry IHC International Horticultural Congress IPPC International Plant Protection Convention ISSER Institute of Social Statistical and Economic Research MOFA Ministry of Food and Agriculture MSW Mango Stone Weevil/Mango Seed Weevil ORID Office of Research Innovation and Development UNCTAD United Nations Conference on Trade and Development xiv    University of Ghana http://ugspace.ug.edu.gh   LIST OF APPENDICES APPENDIX 1. STANDARD LEAST SQUARE ANALYSIS OF VARIANCE SHOWING THE TREATMENT EFFECT AND THEIR INTERACTIONS ................................................... 88 APPENDIX 2. ONE-WAY ANOVA FOR TREATMENTS USED IN THE CIRCLE TRAP ... 88 APPENDIX 3. ONE-WAY ANOVA FOR TREATMENTS IN THE PYRAMID TRAP .......... 88 APPENDIX 4. ONE-WAY ANOVA FOR TRAP TREATMENTS IN AYIKUMA .................. 89 APPENDIX 5. ONE-WAY ANOVA FOR TRAP TREATMENTS IN KPONG ........................ 89 APPENDIX 6. ONE-WAY ANOVA FOR TRAP TREATMENTS IN SOMANYA ................. 89 APPENDIX 7. T-TEST FOR THE TWO TRAP TYPES IN AYIKUMA ................................... 89 APPENDIX 8 . T-TEST FOR THE TWO TRAP TYPES IN KPONG ....................................... 90 APPENDIX 9. T-TEST FOR THE TWO TRAP TYPES IN KPONG ........................................ 90 APPENDIX 10. ONE-WAY ANOVA FOR THE PERFORMANCE OF THE CIRCLE TRAP IN THE THREE STUDY AREAS ........................................................................................ 90 APPENDIX 11. ONE-WAY ANOVA FOR THE PERFORMANCE OF THE PYRAMID TRAP IN THE THREE STUDY AREAS ........................................................................................ 90 APPENDIX 12. ANOVA OF RELEASE RATE CONDUCTED IN THE MANGO ORCHARD ............................................................................................................................................... 91 APPENDIX 13. ANOVA OF RELEASE RATE CONDUCTED IN THE LABORATORY ..... 91 xv    University of Ghana http://ugspace.ug.edu.gh   CHAPTER ONE GENERAL INTRODUCTION 1.1. Background Mango (Mangifera indica L.) (Anarcardiaceae) is an important fruit crop which is grown in the tropical and semi-tropical regions of the world. As a tropical fruit, mango is produced in over 90 countries worldwide with a production of over 28.51 million metric tons in 2005. Asia accounts for approximately 77% of global mango production, and America and Africa account for approximately 13% and 9%, respectively (FAOSTAT, 2007). Mango production comes second after citrus in importance (Khushk & Smith, 1996). In Ghana, mango plays a significant role in providing good nutrition mainly for most rural and urban dwellers (Braimah et al., 2004; CABI & EPPO 2007). The fruit is also exported either fresh or processed to many countries in Europe, Middle East and North America (FAOSTAT, 2013). In Ghana, mango is mainly grown in the Guinea Savannah, Forest Savannah transition and Coastal Savannah zones. These zones cover the Greater Accra region, Southeastern parts of Central region, most of the Volta region, and the three Northern regions. This vast area provides an enormous opportunity for increased mango production. Since the late 1980’s, several commercial mango plantations have been established in response to an increasing export market for mangoes. The fruit export market is a lucrative business, earning the country millions of dollars as foreign exchange (Abdullahi et. al., 2011). It is estimated that Ghana has more than 12,000 ha of land under mango production and most of the fruits produced are exported to Europe and the Middle East. Increasing interest in export of mango has therefore made mango production one of the fastest growing sectors of Ghana’s agriculture and it has been the policy of 1    University of Ghana http://ugspace.ug.edu.gh   government to make mango the leading non-traditional export crop that is expected to ‘contribute to the highest foreign exchange’ for the country thus exceeding cocoa (GEPC, 2009). Mango production like many other cropping systems in the tropical environments is constrained by a number of factors including high cost of inputs such as fertilizer, poor quality planting materials, inadequate and high cost of labour for harvesting and other farm operations, poor post- harvest handling and marketing facilities, lack of machinery for processing, ravages of pests and diseases, and lack of appropriate technologies for pest and disease management to mention a few. Among these production constraints, the most important is the damages caused by pests and diseases. This is because, if not controlled, insect pests and diseases can completely destroy a mango plantation leaving the grower with total crop failure and no income. Also, most mango pests and diseases are of international quarantine importance and their presence in the production system is enough grounds for rejection of fruits on the export market (Clarke et. al., 2005). Their presence also requires that stringent management practices are applied and this increases cost of production. Since the beginning of 2012, importing countries like the United States and European Union have threatened to impose a ban on Ghana’s mango largely because of the incidence of pests. In most of these cases, it has to take the government to issue statements to debunk such claims indicating the importance of pests. It is estimated that the horticultural industry lost over US$10 million in 2013 when U.S. banned export of fruit from Ghana (GEPC, 2014). ‘The mango stone weevil has been identified as a key pest among all the pests which attack mango and thus control it’ will go a long way to sustain the mango industry in Ghana. The insect is important because mango is the only known host plant. Mango stone weevil damage to host 2    University of Ghana http://ugspace.ug.edu.gh   fruit is mainly through feeding activity of larvae and adults and oviposition by females. Feeding has been reported primarily on fruits of mango, but there is also evidence of considerable damage to blossom, leaves and twigs (Medina et al., 2002). A single female can lay up to 15 eggs a day and about 300 in 3 months. The young larvae tunnel into the mango seed and undergo 5-7 instars before pupation (Hansen et al., 1989; Hansen 1993; Grove et al., 2007). The pupa develops inside the seed lasting for about 7 days. The adult remains near the infested crops waiting for the next fruiting season, and has the capability to enter into diapause for several months. Adults are nocturnal and can live up to 21 months (Woodruff, 1970). The success of mango stone weevil as a pest of mango is attributed to the fact that although it has natural enemies, the natural enemies are not capable of providing sufficient controls in both treated and untreated orchards (Louw, 2009). Furthermore, as a direct pest which spends its larval and pupal stages entirely inside the fruit, the adult stage is the most convenient target for insecticide control. Although literature on some aspects of the biology and behavior of mango stone weevil seems to be available, several questions still remain unanswered concerning its ecology and management. For instance, the factors mediating movement of mango stone weevil from aestivating sites to trees are not well known. The lack of accurate and convenient methods for estimating mango stone weevil population density, particularly, in the early crop season, and the associated lack of information on mango stone weevil migration behavior have prevented the development of comprehensive integrated pest management programmes for mango in Ghana. 3    University of Ghana http://ugspace.ug.edu.gh   An important first step to the development of an integrated pest management is pest monitoring which is essential for providing an effective control measure, particularly, when insecticides form the major part of the control programme. Pest management decisions are often made based on the results of sampling methods e.g. traps and lures. An important criterion for any trap monitoring programme used for short-term pest forecasting is that the relationship between trap captures and a corresponding field infestation should be consistent. However, monitoring programmes developed for many insect pests have not achieved this important criterion in that pest infestations have usually proceeded before trap detection (Prokopy et al., 2003, Leskey & Wright 2004a). The potentials for use of host odor baits combined with pheromones have also been reported in several genera of the subfamily Curculioninae (Bartelt et al., 1999), to which mango stone weevil belongs, and investigations have documented the synergism of host plant materials and pheromone combinations in enhancing trap captures (Landolt & Phillips, 1997). Semiochemicals have currently been used as a successful tool in pest management of weevils in annual and perennial crops like peach, apples, cotton, coconut, and sweet potatoes (Leskey & Wright 2004b; Akotsen-Mensah et al., 2010). In pest management, trap and lure types have been examined for monitoring purposes in many cropping systems. However, the efficacies of the lures deployed in traps have shown good potential in some studies, but have also shown poor results in other studies. In spite of some successes in the use of baited traps in monitoring programmes in many fruit growing regions, a number of factors in the field have been reported to greatly influence their performance. Some of 4    University of Ghana http://ugspace.ug.edu.gh   the specific problems that have been identified for the ineffectiveness of the traps and lures used in monitoring include competition from natural odors from host plants and prevailing environmental conditions in the field. For example, Leskey and Zhang 2007 reported that low spring temperatures negatively influenced the performance of baited traps for monitoring adult plum curculio in apple orchards in West Virginia. The effect of temperature is seen, for example, in the rapid degradation of the volatile lure constituents resulting in reduced effectiveness as disproportionate loss of a single lure component can render these compounds behaviorally undetectable (Bartelt et al., 1999). Since conditions differ considerably across locations and most lures depend on temperature- driven mechanisms of release of olfactory stimuli (Leskey & Zhang 2007), it is imperative that lures are evaluated on a regional and local basis before recommendation for grower use. The objective of this study was to evaluate the effectiveness of two widely-used trap types using two host-based fruit volatiles for monitoring populations of mango stone weevils in mango orchards in Ghana. Data from this study, in addition to a degree day model being developed, will provide aid in the development of monitoring techniques and sampling guidelines for mango stone weevil in mango orchards in Ghana. 1.2. Justification Mango is a major fruit crop in Ghana and has recently attained economic significance. Like any crop, mango production is bedevilled with a number of production constraints. Notable among these are insect pests, of which the mango stone weevil Sternochetus mangiferae, is one of the most dangerous in Ghana and other parts of Africa. Being an export crop, there is zero tolerance 5    University of Ghana http://ugspace.ug.edu.gh   for insect damage to exportable mangos. As a result, growers typically have to maintain a prophylactic spray schedule to produce fresh and unblemished fruit for the export market. This extensive use of insecticides has resulted in many drawbacks including pest resistance and environmental pollution. Furthermore, some of the conventional insecticides used in Ghana are banned or restricted in most countries that import mangos from Ghana. The result of this is that mango farmers are left with few insecticide options, making it critical to review the current pest management options. Pest management decisions are often made based on the results of sampling methods e.g. traps and lures. Therefore, traps and lures for pest monitoring should be tested for their performance in stone weevil management. Traps and lures have been used to manage related species such as pecan weevil, plum curculio etc. which have similar biology as the mango stone weevil in other fruit cropping systems (Akotsen-Mensah et al., 2010). Work done in 2013 mango fruiting season showed that the Black pyramid and Circle traps are effective for monitoring the weevil (Tantoh, 2013). We therefore hypothesized that the addition of attractants to the traps would increase trap captures. This research was aimed at finding out the most effective trap and lures for monitoring the mango stone weevil in three mango growing districts in Southern Ghana. The results obtained from this trial would give an idea of the population dynamics of the mango stone weevil which will help farmers know when their crops are most vulnerable. As a result, they would be able to make the right decision in the management of the MSW using the most effective trap and lure combination as part of an integrated pest management strategy. Together with chemical and cultural control methods, weevil attacks would be reduced thereby increasing the availability of higher quality mangos for both the local and international markets. 6    University of Ghana http://ugspace.ug.edu.gh   1.3. Research Objectives 1.3.1. Main Objective The main purpose of this study was to determine the validity of the interaction of two trap types and two new lure types observed in preliminary testing as effective pest management tools. This project sought to evaluate the performance of traps in combination with lures for monitoring the mango stone weevil in three mango orchards in Southern Ghana. 1.4. Specific Objectives 1. To evaluate the performance of traps and lures for the mango stone weevil 2. To determine the effect of air temperature and relative humidity on trap and lure performance 3. To determine the release rate of lures 4. To conduct fruit-damage assessment across the major and minor mango fruiting season 7    University of Ghana http://ugspace.ug.edu.gh   CHAPTER TWO LITERATURE REVIEW 2.1. The Mango Crop The mango tree is believed to have evolved as a canopy layer in the tropical rainforest of Southeast Asia. It is said to have been introduced to West Africa in the early 16th Century by the Portuguese (Medina et al., 2002). Mature trees attain heights of up to 30 meters and can survive for more than one hundred years (Kaur et al., 1980). It is an evergreen tree with alternate, oblong ovate leaves that are spirally arranged. Older leaves are 12-15cm in length. The inflorescence is erect and widely branched with hundreds of small flowers that are pink to red in colour and 6- 8mm in diameter. Both female and male flowers are found within a single inflorescence. The pollination of the mango crop is done by insects, particularly flies (Singh et al., 1962; Jiron and Hedstrom, 1985). Mango grows in a slightly acidic (5.5-7.5) and well-drained soil, whether it is sandy, loam or clay (Young et al., 1965). It is somewhat tolerant to alkalinity (Kadman et al., 1976). Mango is also drought-tolerant, and can withstand occasional flooding (Singh, 1960). For best flowering and fruit set, good timely rainfall is necessary rather than the total rainfall. In tropical and subtropical regions of the world, mango grows well in warm climates at elevations from sea level to about 1200m above sea level and can grow and develop well in areas with a minimum annual rainfall of 1000mm (Braimah et al., 2004; Akurugu, 2011). 8    University of Ghana http://ugspace.ug.edu.gh   2.2. Mango Varieties Propagated in Ghana There are over 100 mango varieties cultivated in Ghana of which a few are of commercial importance (Singh, 1978). The early cultivars introduced in Ghana included ‘Peter’, ‘Blackman’, ‘Kensington’, ‘Divine’, ‘Julie’, and ‘Ceylon1’ from Trinidad, ‘Jaffna and ‘Rupee’ from Ceylon as well as other cultivars from India. Currently, mango varieties grown in Ghana include ‘Kent’, ‘Keitt’, ‘Palmer’, ‘Haden’, ‘Tommy Atkins’, ‘Irwin’, ‘Sensation’, ‘Julie’, and the local variety (GEPC, 2005). About 16 mango varieties are now cultivated in the Shai Osudoku district of the Greater Accra Region, and the Yilo and Manya Krobo districts in the Eastern Region of Ghana; of which ‘Keitt’ and ‘Kent’ are of greatest economic importance, followed by ‘Haden’, ‘Palmer’ and ‘Julie’ in order of importance (Odzeyem, 2007). 2.2.1. ‘Keitt’ Mango This fruit is large (400-800g) and ovate tapering with slight nose-like protuberance above its tip. It is green to orange-yellow as it ripens; firm flesh with a piney sweetness and minimal fiber surrounding the seed area and is a late fruiting mango variety often available in the fall (GEPC, 2005; Susser and Schneider, 2001). It is an Indian strain thought to have originated in Florida in 1945 like the ‘Haden’ from a seedling of Mulgoba Homestead. 9    University of Ghana http://ugspace.ug.edu.gh   2.2.2 ‘Kent’ Mango This mango variety was developed in Florida in 1944, and it is a direct descendant of the Brooks cultivar which was derived from the Sandersha seedling. It is highly susceptible to ‘anthracnose’ fungal disease and also sensitive to cold (Campbell, 1992). It is large (500-700g) and has a regular oval shape, with plump cheeks, greenish-yellow color with red shoulder. It is very rich and sweet with fiber-free flesh like butter when ripe. 2.2.3. ‘Tommy Atkins’ Mango This mango cultivar was developed and grown for commercial export in Florida in the early 1920's. The fruit is a regular oval, medium to large sized (300 - 650g), yellowish-orange with deep red to purple blush, thicker skinned, juicy but firm with medium fiber. Its susceptibility to the ‘anthracnose’ fungal disease is low as compared to the other exportable varieties (Campbell, 1992). 2.2.4. ‘Haden’ Mango This mango fruit is oval, large (500-650g), yellow almost entirely washed over with an orange- red color, mild in flavor with a small amount of fiber which is highly susceptible to anthracnose and also highly sensitive to cold (Campbell, 1992). It was developed by Captain Haden (1910) in Florida from Mulgoba seedling, Bombay, India. 10    University of Ghana http://ugspace.ug.edu.gh   2.3. Mango Production and Distribution Mango is one of the most important tropical fruit crops in the world and is fifth-ranked in production among major fruit crops worldwide. About 100 countries are recorded as mango- producing countries in current FAO statistics (IHC, 2014). Although mango has a long history of cultivation and is very popular fruit in tropical regions, its cultivation has recently expanded to countries in temperate zones by use of protected cultivation. People in these areas recognize mango as a new exotic fruit. Thus, mango still has much economic potential for the globalized markets in the world. But further understanding of mango from many aspects is still required for development of the new technologies for production (IHC, 2014). Global production of mangoes was forecasted to reach 30.7 million tons in 2010, accounting for nearly 50 percent of world tropical fruit production. Slightly more than 77% of world mango output was expected to be produced in Asia and the Pacific by the end of the projections period (FAOSTAT, 2007). Currently, FAO estimates that mango harvest will be around 30 million tons by the end of 2015, i.e. 35% of the production of the world`s tropical fruit. Sixty-nine (69) percent of the total amount will be obtained in Asia and the Pacific countries (India, China, Pakistan, Philippines and Thailand), 14% in Latin America and the Caribbean (Brazil and Mexico) and 9% in Africa. Mango production is estimated to be about 158,000 tons in developed countries like U.S.A., Israel and South Africa. The UN forecasts put India as the world's largest mango producer with 40% of the total crop produced (11.6 million tons). World mango import is estimated to increase to 1.4% in 2015 totaling 844,246 tons. The lead countries demanding this fruit are the United States and the European Union. Net purchases by the EU increased about 2.5% per year, until reaching 223,662 tons in 2015. France, the Netherlands and the UK are ahead of Spain in 11    University of Ghana http://ugspace.ug.edu.gh   volumes of purchases. Meanwhile, U.S. mango import is also expected to increase by 1% per year until it reaches 309,115 tons (FAOSTAT, 2014). The West African rate of mango consumption has increased from about 15000 to over 22000 tons that is a rise of about 7000 tons with Nigeria alone consuming almost half of West Africa’s production increasing its demand on their market. Table 1 shows the top ten mango producing countries in the world in the year 2010. Table 1. Top Ten Mango Producing Countries in the World RANK COUNTRY PRODUCTION (in tons) 1 India 15,188,000 2 China, mainland 4,350,000 3 Thailand 2,600,000 4 Indonesia 2,131,139 5 Pakistan 1,888,449 6 Mexico 1,827,314 7 Brazil 1,249,521 8 Bangladesh 889,176 9 Nigeria 850,000 10 Philippines 800,551 Source: FAOSTAT, 2014 12    University of Ghana http://ugspace.ug.edu.gh   In 2011, Africa’s mango production was estimated at 4,667,229 tons (FAO, 2013; UNCTAD, 2012). Burkina Faso, Gambia, Cape Verde, Benin, Cote d’Ivoire, Ghana, Mali, Guinea, Guinea Bissau, Nigeria, Niger, Senegal and Sierra Leone are among the major mango producing countries in West Africa. Mango production in these West African countries from the year 2009 to 2011 is shown in table 2. Table 2. Mango Production (in tons) in 13 West African countries from 2009-2011   Country Year 2009 2010 2011 Benin 14,412 13,700 13,900 Burkina Faso 10,737 10,962 13,154 Cape Verde 7,002 6,500 6,800 Cote d’Ivoire 42,232 45,206 46,960 Gambia 1,343 1,200 1,300 Ghana 75,000 80,000 85,000 Guinea 16,500 163,900 157,700 Guinea Bissau 6,576 6,714 8,057 Mali 47,392 47,800 50,000 Niger 170,572 175,000 169,179 Nigeria 83,500 850,000 850,000 Senegal 100,000 100,000 100,000 Sierra Leone 17,935 18,310 21,972 Source: FAOSTAT, 2014 13    University of Ghana http://ugspace.ug.edu.gh   In Ghana, commercial mango production is mainly found in two distinct agro ecological zones (the savannah and transitional) which constitute Northern Ghana, around Tamale and Southern Ghana covering Greater Accra, parts of the Eastern and the Volta regions. These agro ecological zones are characterized by hot temperatures, high light intensity, abundant moisture and moderate rainfall (Personal communication with mango farmers). 2.4. Economic Importance of Mango Mango is one of the fruits with a very high nutritional content. It is a rich source of vitamins A and C, providing an affordable source of these vitamins. It is second to citrus in importance; and second to banana as the most consumed tropical fruit in the world (UNCTAD, 2012; ICRAF, 2003). Ripe pulp of mango provides 74 Kcal of energy per 100 g of edible portion; and has a moisture content of 79.2-82%, total soluble solids of 12.9-20.8%, total sugars of 10-17.3%, non- reducing sugars of 7.27-12.35%, ash content of 0.49-0.58% and crude protein content of 0.38- 0.62%); with respect to fresh fruit weight (Hussain et al., 2002). The production of mango as one of the major non-traditional export crops in the Ghanaian horticultural industry has provided employment for many Ghanaians. According to GEPC (2009), export of mangoes fetched $234,950. A report by ISSER (2009) indicated that mango production increased from 823.73 tons in 2007 to 857.7 tons in 2008 representing a 4.1% increase over the period. However, export earnings of mango across the period intensely decreased from $998,160 in 2007 to $581,820 in 2008, despite the increase in production. From 2008 to date, Ghana has recorded a deficit of negative 54.97% on foreign exchange earnings on mango to the international market largely due to the discovery of a highly invasive, prolific and polyphagous fruit fly species, Bactrocera invadens (now B. dorsalis) in Africa (Lux et al., 2003; Drew et al., 2005; Billah et al., 2006). 14    University of Ghana http://ugspace.ug.edu.gh   Despite the recent global economic crisis and turndown which has seen the price of the mango fruit drop from $11,212 per ton to US $608 per ton, mango still continues to be the second largest contributor of foreign exchange to the Ghanaian economy (ISSER, 2009). Fruit production (including mango) in general is one of the fastest growing agricultural sectors in Africa and this provides income and employment for both growers and exporters (Ekesi & Billah, 2007). It improves the livelihoods of the farmers by creating employment and increasing their income levels. According to Medina et al., (2002), mango is regarded as one of the most recommended fruits with medicinal importance to fight beriberi, heal bronchial diseases and cure brain fatigue, insomnia, wrestle heart burn and mental depression. Some volumes of mango are processed for preservation into various products such as jams, pickles, puree, juices, fruit salads, canned slices and dehydrated products (GEPC, 2005). 2.5. Constraints to Mango Production in Ghana Mango production like many other cropping systems in the tropical environment is constrained by a number of factors including high cost of inputs such as fertilizer, poor quality planting materials, inadequate and high cost of labour for harvesting and other farm operations, poor post- harvest handling and marketing facilities, lack of machinery for processing, ravages of pests and diseases and lack of appropriate technologies for pest and disease management (Abdallah, 2012). Among these production constraints, the most important is the ravages of pests and diseases. This is because, if not controlled, insect pests and diseases can completely destroy a mango plantation leaving the grower with total crop failure and no income. Also, most mango pests and diseases are of international quarantine importance and their presence in the production system is 15    University of Ghana http://ugspace.ug.edu.gh   enough grounds for rejection of fruits on the export market. Their presence also requires that stringent management practices are applied and this increases cost of production. Among the most notable pests associated with mango production in Africa are fruit flies, mango stone weevil, Sternochetus mangiferae (Fabricius); leafhoppers, Idiocopua nitidus (Walker), I. niveosparsus (Lethiery) and I. clypealis; mango shoot caterpillar, Penicillaria jacosatrix (Guenee); mango mealy bug, Rastococcus invadens (Williams); scale insects, Chloropulvinaria polygonata, Aspidiotus destructor (Signoret) and Rastococcus sp.; thrips, Selenothrips rubrocintus (Giard); black ants (Crematogaster sp.); sucking bugs, Anoplochnemis curvipes; and the spiraling whiteflies, Aleurodicus dispersus (Russel) (Obeng- Ofori, 2007). According to Ekesi and Billah (2007), the new invasive fruit fly (Bactrocera dorsalis) and the mango stone weevil (Sternochetus magniferae) are the most dangerous species causing the greatest economic damage to mango across Africa. 2.6. The Mango Stone Weevil, Sternochetus mangiferae (F) 2.6.1. Taxonomy and Distribution of the Mango Stone Weevil, Sternochetus mangiferae (F) The mango stone weevil is classified under the Kingdom: Animalia, Phylum: Arthropoda, Superclass: Hexapoda, Class: Insecta, Infraclass: Neoptera, Order: Coleoptera, Suborder: Polyphaga, Superfamily: Curculionoidea, Family: Curculionidae, Subfamily: Chryptorhychinae, Tribe: Chryptorhynchini, Genus: Sternochetus, Species: Sternochetus mangiferae (F) (EPPO, 2011). Some of the common names include mango seed weevil, mango weevil and mango nut or stone weevil (Grove et al., 2007; Pest Alert, 2000). 16    University of Ghana http://ugspace.ug.edu.gh   Though the mango stone weevil originates from the Indo-Burma sub-region, it also occurs in Asia, Australia, Oceania, North, South and Central America as well as Africa (Follet, 2002; CABI, 2014). S. mangiferae does not occur in the Philippines. However, it has been intercepted on numerous occasions in mangoes from the Philippines by the Animal and Plant Health Inspection Service of the United States Department of Agriculture (Anonymous 1988a, 1989a). In Africa, the stone weevil occurs in Guinea, Ghana, Nigeria, Gabon, Liberia, Kenya, Malawi, Madagascar, Mozambique, Mauritius, Reunion, Central African Republic, Zambia, Seychelles, Tanzania, Uganda and South Africa (CABI & EPPO, 2014). Figure 1 shows the geographical distribution of the mango stone weevil in Africa. 17    University of Ghana http://ugspace.ug.edu.gh     Figure 1. Geographical Distribution of the Mango stone weevil in Africa (orange marked) Source: http://www.infonet-biovision.org/default/ct/100/pests 2.6.2. The Biology of the Mango Stone Weevil The mango stone weevil is univoltine (i.e. has one generation per year) (Follett, 2002). Oviposition by females takes about 3-4 days after mating when fruits are about marble-size (Shukla & Tandon, 1985). A single female can lay 15 eggs per day, with a maximum of almost 300 eggs over a three month period (Balock & Kozuma, 1964). The eggs are creamy-white when freshly laid; elliptical, 0.72-0.87 mm long and 0.24-0.34 mm wide. Eggs are laid singly on the skin of immature fruit or sometimes on the stems; most eggs are laid on the sinus of the fruit (Shukla et al., 1985). The adult female carves out a cavity on the 18    University of Ghana http://ugspace.ug.edu.gh   fruit surface and deposits an egg, which is immediately covered by a brown exudate produced by the wound (Follett, 2002). Incubation requires 5-7 days, depending on season and temperature (Balock & Kozuma, 1964). After hatching, the larva burrows through the flesh into the developing seed usually within the first day (Balock & Kozuma, 1964). The first larval-instar has a white body, legless, elongate, cylindrical, extremely slender, 1.34-1.44 mm long, 0.30-0.41 mm wide with a black head. Final (4th or 5th) instar has a white body, legless, curved, typical curculionoid form, 16.0-18.0 mm long and 6.0-9.0 mm wide (Shukla & Tandon, 1985). Larval development usually occurs within the maturing seed, though occasionally may occur within the flesh; and the larvae feed within the seed and pupate in the seed cavity (Hansen et al., 1989; Follett, 2002). The pupal duration period is about 7 days (Balock & Kozuma, 1964; Shukla and Tandon, 1985; Hansen et al., 1989). The pupa is whitish when newly formed, changing to a very pale-red just prior to adult eclosion; 7.0-10.0 mm long and 6.0-8.0 mm wide. Upon maturation, the adults rapidly move out of the seeds and seek hiding places by crawling rather than flying (Shukla & Tandon, 1985). Adults emerge from the fruit by chewing a hole through the seed wall, and then boring through the fruit pulp (Braimah & Van Emden, 2010). The body of the adult is compact, 7.5-9.5 mm long, black, covered by black, greyish or yellowish scales; pronotum is subparallel-sided in basal third only; elytra with interstices 3, 5 and 7 strongly carinate, indistinct oblique pale humeral stripe, elongate, gradually declivous behind; femora with single large tooth ventrally, profemora stout, distinctly clavate; tarsal claws simple, free; female with elevated ridge at pygidial apex, absent in male (EPPO, 2011). The entire life cycle takes between 40 to 50 days. Plate 1 shows the life cycle of the mango stone weevil. 19    University of Ghana http://ugspace.ug.edu.gh     Plate 1. Life Cycle of the Mango Stone Weevil     2.6.3. Host and Mechanism of Host Selection of the Stone Weevil The mango stone weevil is monophagous with mango as the only known host plant. According to Pest Alert (2000), no alternative hosts are known and complete development of the life cycle occurs only in mangoes. Oviposition was observed in peaches, litchi, potatoes, apples and several varieties of apples in an experiment carried out by Balock and Kozuma (1964) as well as Pest Alert (2000) but the larvae did not develop to attain maturity. 20    University of Ghana http://ugspace.ug.edu.gh   Though traps and lures have been used to manage related species such as pecan weevil, plum curculio etc. which have similar biology as the mango stone weevil in other fruit cropping systems (Akotsen-Mensah et al., 2010), yet there is no pheromone trap identified for the stone weevil. Work conducted by De Jesus et al. in 2004 revealed that the mango pulp weevil, Sternochetus frigidus (F.) is attracted to chemicals contained in the mango flowers. A similar study conducted by Braimah and Van Emden in 2010 with arena and olfactometer bioassays also revealed that adult stone weevils preferred flower parts to other parts of the mango plant. 2.6.4 General Behaviour of Mango Stone Weevil Adult weevils as reported by Joubert and Pasques (1994), are extremely inactive but activity slightly increases at night since they are nocturnal. Feeding, mating and egg laying occur at dusk; and although winged, they rarely fly long distances but are able to fly between trees and do not move far from the parent tree until the next fruiting season (Schotman, 1989; Schoeman 1987; Woodruff & Fasulo, 2006). During unfavourable periods, they hide in crevices and other sheltered places where they are camouflaged in and/or under infested trees (De Villiers, 1984). They also hide and camouflage very well on the barks of the mango tree trunks and branch terminals during non-fruiting seasons (Tantoh, 2013 unpublished). Stone weevils may also hide in other areas apart from the mango bark especially in cracks and crevices in other tree barks; and have been known to survive more than four and a half months without food and water, and 21 months with availability of food and water (Braimah et al.,2009; Shukla & Tandon, 1985; Balock & Kozuma, 1964). 21    University of Ghana http://ugspace.ug.edu.gh   2.6.5. Economic Importance of Stone Weevil Damage Mango stone weevil is regarded as a destructive pest of mango in growing areas and a serious pest in Ghana because of the developing export trade in mangoes (Braimah et al., 2009). No external symptoms of attack by the stone weevil are readily visible on infested fruits and yields are not significantly affected, since the larvae usually feed entirely within the stone and very rarely in the pulp of the fruit. Probably its greatest significance as a pest is to reduce the germination capacity of seeds greatly and to interfere with the export of fruit, because of quarantine restrictions imposed by importing countries. In India, all cultivars are susceptible and levels of infestation vary between 48-87% (Bagle & Prasad, 1985). The mango stone weevil is estimated to have consequences which are unlikely to be discernible at the national level and of minor significance at the regional level. The low quarantine rejection threshold of one fruit in 40 set in the export market suggests that the solution to the problem posed by the weevil requires socio-economic, political and scientific initiatives (Braimah et al., 2009). The incisions made by ovipositing MSW female, and larval penetration wounds, generally heal as the mango fruit increases in size, making it difficult to notice these lesions (Schoeman, 1987; Hansen, 1993; Louw, 2009). With time it may be nearly impossible to distinguish infested from non-infested fruit without opening the seed of the fruit (CABI & EPPO, 2005). Fruits are not adversely affected by infestation except in rare instances where larvae feed and pupate within the pulp or when they emerge from seeds and tunnel up through the pulp (Balock & Kozuma, 1964). A study conducted in South Africa by Kok (1979), showed that adult weevils tended to leave the seed and tunnel through the fruit after harvest of late-maturing varieties, leaving a scar on the outside which served as a site for secondary fungal infection and this renders the fruit unfit for human consumption. Internally infected fruits rot from the outer surface of the stones. Infestation 22    University of Ghana http://ugspace.ug.edu.gh   reduces the germination of seed and causes premature fruit drop (Verghese et al., 2005a; Follet, 2002). The mango seeds also show holes and the cotyledons turn black and remain merely a rotten mass. Seeds with damaged embryo and greatly reduced food reserve in the cotyledons, fail to germinate. Plate 2 shows the different types/stages of damage to the mango fruit by the stoneweevil.   Plate 2. Types/stages of mango fruit damage by the stone weevil Source: Cornelia Estelle Louw (unpublished) www.etd.uovs.ac.za/ETD-db/theses 23    University of Ghana http://ugspace.ug.edu.gh   2.6.6. Effect of Some Environmental Factors on the Stone Weevil The effect of certain environmental factors, especially temperature, relative humidity and rainfall, has been studied on the durations of the life cycle of the mango stone weevil under laboratory conditions. The durations of the life cycle of the weevil have been observed to vary from season to season. In India, the longest and shortest durations of the life cycle have been reported to be 55 days and 40 days respectively. The longest was observed in 1988 whiles the shortest duration was 1987 (Devi, 2007). Environmental factors have also been observed to play a vital role on the biology of the weevil. An average temperature of 28 °C and relative humidity of about 73% were found to be favourable conditions for the longer life cycles whereas the average minimum temperature of about 26 °C with 75% relative humidity have been observed to shorten the life cycle of the mango stone weevil (Devi, 2007). Braimah et al., (2009) reported that mango fruit found on trees in cocoa plantations had high incidence of mango stone weevils due to the high humidity usually experienced in cocoa farms.  The prevalence of the weevils in the forest areas of Ghana especially in established cocoa farms where mango trees are found is because of the effect of relative humidity on infestation levels of the mango fruits (Braimah et al., 2009). These forest areas usually have relatively higher humidity all year round. Balock and Kozuma (1964) showed that egg hatch took 7 days under temperature fluctuations of between 18 to 28 °C in March and early April whiles in late May and early June, it took 5-6 days in higher temperatures, indicating that temperature has an influence on egg hatching. However, one of the biggest threats to stone weevil survival is dessication (Braimah & Van Emden, 2010). 24    University of Ghana http://ugspace.ug.edu.gh   2.6.7. Pest Management Strategies No single pest management strategy for the mango stone weevil is likely to provide effective and sustainable control. The integration of approaches, however, offers the possibility of such sustainable control (Braimah & Van Emden, 2010). Some of the integrated pest management strategies that have been used for sustainable control of the mango stone weevil are discussed below. 2.6.7.1. Host Plant Resistance The potential mechanisms of host plant resistance are cultivars that produce no seed, those that form seeds with a hard or insect-toxic covering early, or those that fruit off season (Hansen, 1993; Grove et al., 2007). Most cultivars grown in India and Hawaii have shown susceptibility to stone weevil infestation (Bagle & Prasad, 1984; Hansen et al., 1989). The cultivar ‘Itamaraca’ has shown some resistance, because it is reported to induce off-season flowering and therefore produces weevil free fruits (Balock & Kozuma, 1964). The cultivar ‘Jacqueline’ though produces fruits that do not meet the required export standards, yet it is the only near seedless variety in Ghana. Some of the early seed cultivars in Ghana include ‘Irwin’, ‘Palmer’ and ‘Haden’. However, there is very little genetic variability in the mango germplasm in Ghana, as in the case for the rest of West Africa, and there are no varieties that fruit regularly during the off-season (Braimah & Van Emden, 2010). This implies that there is the need for the introduction of a new germplasm and pursue a vigorous hybridisation and selection programme to produce mangoes with the requisite desirable traits.   25    University of Ghana http://ugspace.ug.edu.gh   2.6.7.2. Cultural Control Cultural control is an important strategy, and it is based on the manipulation of the weevil’s habitat to adversely affect its survival and subsequently promote healthy growth of the mango plant. Farm sanitation is valuable for its contribution to an integrated approach to the sustainable management of the mango stone weevil although the available evidence suggests that farm sanitation as a control technique is ineffective and labour-intensive (Pena et al., 1998). Field sanitation results in very limited control of the weevil even though it is widely recommended. Only 22% reduction in stone weevil infestation was achieved when Dey and Pande (1987), experimentally evaluated the technique of field sanitation. No significant reduction in weevil populations was recorded in Hawaii in a study conducted by Hansen and Amstrong (1990), using this technique. Removal and destruction of nearly matured and matured dropped fruits is one of the techniques of field sanitation. Such fruits should be buried deeply, at least 1 m below the soil surface as soon as possible (Braimah & Van Emden, 2010). Pruning opens up the tree canopy for light penetration and ventilation, and this ensures less humid microenvironment within the tree canopy making the aestivation of weevils less suitable. Refusal to remove tall weeds reduces air movements and keeps the microclimate within a plantation humid, so favouring the weevil (Braimah et al., 2009). 2.6.7.3. The Use of Semiochemicals For Monitoring These are chemicals emitted by plants and animals which modify the behaviour of receptor organisms of the same kind or different kind. Depending on the purpose, they are classified as pheromones, allomones and kairomones. Organisms utilize information they percieve from their 26    University of Ghana http://ugspace.ug.edu.gh   environment to improve food location, avoid predators, find mate etc. Plant semiochemicals are known to produce a wide range of behavioral responses in insects. Some insects sequester or acquire host plant compounds and use them as sex pheromones or sex pheromone precursors. Infochemicals which constitute a subcategory of semiochemicals can be used in pest monitoring, as well as a control measure through “lure and kill”, mass trapping and mating disruption. Sex and aggregated pheromones are species-specific attractants, and traps baited with these can be used as specific monitoring tools for the target pest species. Tools like attractants produced from the study of chemical ecology of the stone weevil are valuable for manipulating the behaviour of the weevil, and are important for trapping the weevils before they infest the mangoes during the off-season (Braimah & Van Emden, 2010). A study conducted in Ghana by Braimah and Van Emden in 2010 with arena and olfactometer bioassays revealed that adult stone weevils preferred flower parts to other parts of the mango plant, therefore the extraction of essential oils from the mango flowers can serve as attractants for the weevil. 2.6.7.4. Trapping Traps can be used as devices for detecting the presence of pests and in principle, they can be calibrated to provide a quantitative measure of the pest density which may be possible to relate to prospective levels of pest damage (Wall, 1989). The development of trapping techniques together with semiochemicals could be valuable tools in monitoring and managing the stone weevil (Braimah & Van Emden, 2010). According to Johnson et al., (2002), trapping has been used to successfully manage insects like the plum curculio and pecan weevil which have a similar biology and ecology as the mango stone weevil. Therefore, effective monitoring of the 27    University of Ghana http://ugspace.ug.edu.gh   stone weevil can also be achieved through the use of these trapping techniques. The black and yellow pyramid traps, circle traps and the cone emergence traps are among the many traps which have been used in the United States to manage the plum curculio and they are now widely accepted. Pyramid and circle traps with lures (benzaldehyde, grandisoic acid and plum essence) evaluated by Akotsen-Mensah et al., (2010), in Alabama peaches revealed a significant increase in trap capture in the number of plum curculios. In Ghana, Tantoh (2014), found that these traps especially the black pyramid and the circle traps can be used to capture the mango stone weevil; and can thus serve as a good monitoring tool. 2.6.7.4.1. Pyramid Traps The Black and Yellow pyramid traps also referred to as Tedder’s traps were developed to mimic the tree trunk as the first dark object that may be seen by the adult weevils upon emergence within and outside their overwintering sites of peach or pecan orchard (Tedders & Wood, 1994; Bloem et al., 2002). They are easily constructed using masonite or particle board, and plywood (Tedders & Wood, 1994). The Black pyramid traps have white vertical lines at the edges which reflect light at night; and the weevils perceive these traps as trees. The Pyramid traps are known to mimic the silhouette of the tree trunk which directs the insect to the tree. Plate 3 shows a picture of the Black and Yellow pyramid traps. 28    University of Ghana http://ugspace.ug.edu.gh     Plate 3. The Black (Left) and Yellow (Right) Pyramid traps in a mango and peach orchards respectively   29    University of Ghana http://ugspace.ug.edu.gh   Plate 4. A modified Circle Trap tied with a masking tape in a Mango Orchard in Southern Ghana 30    University of Ghana http://ugspace.ug.edu.gh   2.6.7.4.2. Circle Traps The Circle trap was developed in 1997 by Circle, a farmer in the United States following the description by Mulder et al., (1997). Also known as fruit tree screen trap, the Circle traps were developed because the cone emergence and the pyramid traps were hindrances to mowing and grazing, and could easily be damaged by livestock and mowing equipment. The catches of the circle traps were comparable to the pyramid trap in plum curculio monitoring in works carried out in some peach orchards in both wild and cultivated habitats (Bloem et al., 2002). Plate 4 shows a picture of the circle trap set up in a mango orchard in Southern Ghana. 2.6.7.5. Chemical Control A number of insecticides have been evaluated for controlling adult mango stone weevils, especially during flowering and fruiting of the mango crop (Balock & Kozuma, 1964). These insecticides (Acephate, thiamethoxan, carbaryl, deltamethrin, dimethoate, endosulfan, ethofenprox, fenthion, fenvalerate, imidacloprid, monocrotophos and prothiofos) have been effective in reducing populations of the stone weevil and infestation of fruits, and are all applied at least twice during flowering (Verghese et al., 2005b; Shukla & Tandon, 1985). In India, Bangle and Parsad (1985), found that carbaryl (Carbamate), and monocrotophos and dimethoate (Organophosphates) were the most effective insecticides when tested against the weevil. Also Deltamethrin (Pyrethroid) was found to be the effective foliar spray, followed by fenthion, while carbaryl and fenvalerate were less consistent (Shukla & Tandon, 1985). 31    University of Ghana http://ugspace.ug.edu.gh   In a study conducted in India to access some selected insecticides for their efficacy against the mango stone weevil, Verghese et al., 2005b reported that incidence of mango stone weevil reduced drastically from as high as 30% to a range of between 3.3% and 14.8% over a 3 year period when the insecticides were being used. Insecticides used for the study included; deltamethrin, acephate, cabaryl and ethofenprox. Some countries have recommended certain synthetic insecticides for the control of the mango stone weevil within their borders. For example in South Africa, deltamethrin, fenthion, fenvalerate and esfenfalerate have been recommended for control of the mango stone weevil ( Ned et al., 2002). It is not ecologically advisable to use synthetic insecticides for the management of weevils in Ghana and the rest of West Africa (Braimah &Van Emden, 2010). Due to the inactivity and nocturnal behavior of the weevil during the day, the use of synthetic insecticides therefore poses a lot of problems (Joubert & Pasques, 1994). Insecticide application therefore needs to be carried out to coincide with the peak activities of the weevil. Botanical extracts such as neem from Azadirachta indica have proved to be suitable alternatives to synthetic insecticides (Schmutterer, 1990). However, botanical extracts have shown limited success in the control against the mango stone weevil; and in Ghana both crude neem extract and refined extract neemazal failed to achieve any degree of control of the weevil (Braimah et al., 2004). Azadirachtin (plant origin) and fish oil rosin soap (animal origin) obtained intermediate levels of control of 27.4% and 23.0% respectively, which were not significantly different from the untreated control in field studies conducted to evaluate botanical and animal origin insecticides against mango seed weevil in ‘Alphonso’ mangoes (Verghese et al., 2005b). 32    University of Ghana http://ugspace.ug.edu.gh   2.6.7.6. Quarantine and Phytosanitory Measures These control measures are employed when importing mangoes from countries infested with the stone weevil so that infestations caused by the pest in both free and affected areas can be prevented or minimized. The aim of quarantine and phytosanitary measures is to eliminate, sterilise or kill regulated pests in exported fruit to prevent their introduction and establishment in new localities. Such treatments include exposure to heat or cold, irradiation and fumigation (Braimah & Van Emden, 2010). According to Braimah et al., (2009), the mango stone weevil is considered to be economically significant pest with an international quarantine rejection threshold of 1:40. The menace that the weevil poses as a pest is only apparent when it is encountered within the pulp while the fruit is being processed. They are difficult to detect in the field since they develop inside the seed with the fruits sometimes appearing externally unaffected. As a typical monophagous insect, the chances that it will survive in areas where mangoes cannot thrive are negligible (Braimah & Van Emden, 2010). It is recommended that physiologically matured fruits are submerged in hot water at 558 oC for 5–10 minutes to kill weevils in hot water treatment. Until recently, quarantine technologies such as irradiation were controversial. However, since 2004, irradiation has been approved as a phytosanitary measure by the International Plant Protection Convention (IPPC) (2004) and the Codex Alimentarius (FAO), and can no longer be used as a non-tariff trade barrier by any importer (Follett, 2007). There is now a proposed irradiation dose of 100 Gy when sterilizing the stone weevil in the mango fruit. The major advantage of a good radiation system is that either the sterilisation or the kill that occurs provides enough quarantine security (Follett 2007). Gamma radiation for instance, was found to be most efficient in killing and destroying the mango stone weevil (Balock & Kozuma, 1964). 33    University of Ghana http://ugspace.ug.edu.gh   There is no effective fumigant for eliminating mango stone weevils from fruit (Balock & Kozuma, 1964). Even though methyl bromide fumigation for 8 hours at 38.2 g under normal atmospheric pressure killed all stages, yet fruit quality was adversely affected. All larvae and pupae and 95% of adults were killed with 2 hour fumigation at the same dosage in a vacuum at 21.1°C to 26.7°C, but fruit damage was observed (Balock & Kozuma, 1964). In all these control measures, there are still some disadvantages especially in the domain of fruit quality damage and cost; and in Ghana, the cost of maintenance, purchasing, hot water treatments and running of the irradiation equipment have been major constraints to the small holder farmers (Braimah and Van Emden, 2010). 2.6.7.7. Biological Control This method of control involves the use and manipulation of the natural enemies of the pest to keep pest population below economic damage. Most of the mango producers in the West African subregion are resource-poor farmers and lack the technical knowledge for effective and sustainable pest management approaches. Therefore a classical biological control programme for S. mangiferae, where most of the cost is borne by the national government or donor agencies, would be a very good option (Braimah & Van Emden, 2010). Although, the stone weevil has fewer natural enemies and the adults may be preyed upon by ants, lizards, birds and rodents, no effective natural enemies specific to the weevil have been recorded anywhere (Peng & Christian 2007; Hansen, 1993). According to Braimah and Van Emden (2010), the use of microbial organisms such as entomopathogenic fungi is not largely explored in biological control of the weevil. Two strains of Beauveria bassiana (Balsamo) Vuillemin from S. mangiferae were 34    University of Ghana http://ugspace.ug.edu.gh   isolated in South Africa but neither was effective in killing adult weevils in the laboratory and in the field (Joubert & Labuschagne, 1995). Ninety percent mortality of test weevils was observed in Ghana by Braimah et al. (2004) when a crude formulation of dead weevils that showed clear signs of fungal infestations was used. It was later identified that the culture contained both Metarhizium anisopliae (Sorokin) and B. bassiana. The use of weaver ants have been observed to be effective for reducing infestation of fruits by the weevils and other pests (Van Mele & Vayssieres 2007). In Asia, green ants have been used as generalist predators in the management of mango stone weevils. Peng and Christian (2007), found Oecophylla smaragdina to be an effective biocontrol agent and advised that keeping their populations high will ensure successful control of the stone weevil. 35    University of Ghana http://ugspace.ug.edu.gh   CHAPTER THREE METHODOLOGY 3.1. General Procedures 3.1.1. Study Areas The field studies were conducted in two mango producing regions in Southern Ghana: Eastern and Greater Accra Regions where mango is commercially grown. Two districts were selected from the Eastern Region (Yilo and Manya Krobo) and one district from Greater Accra Region (Shai Osudoku). In each district, one mango orchard was selected for the evaluation of the trapping and monitoring activities. The farms were located at Kpong (Manya Krobo), Somanya (Yilo Krobo) and Ayikuma (Shai Osudoku). 3.1.2. Description of the Study Areas The Shai Osudoku District (formerly part of Dangbwe West) is situated in the Southeastern part of Ghana, lying between latitude 5° 45’ south and 6° 05’ North and Longitude 0° 05’ East and 0° 20’ West. The District has a total land area of 1,442 square kilometres, making it the largest in the Greater Accra Region. The Administrative Capital of the District is Dodowa. The District shares boundaries with Yilo Krobo and Manya Krobo Districts and Asuogyaman District to the North respectively, to the East with Ada West, to the South with Ningo-Prampram District and to the West with Akwapim North Municipal and Tema metropolitan respectively. Temperatures are appreciably high for most parts of the year with the highest during the main dry season (November - March) and lowest during the short rainy season (July - August). They average a few degrees lower on the coast and close to the Akwapim range than they do over most of the plains. The absolute maximum temperature is 40 °C. Rainfall is generally very low with most of 36    University of Ghana http://ugspace.ug.edu.gh   the rains, very erratic in nature and coming mostly between September and November. Mean annual rainfall increases from 762.5 mL on the coast to 1220 mL to the North and Northeast close to the foothills of Akwapim Range and on the summit. The predominant vegetation type found in the district is of the short grass savannah interspersed with shrubs and short trees, a characteristic of the Sub-Sahelan type. However, some light forest with tall trees is also found along the foothills of the Akwapim Range especially around Dodowa, Ayikuma and Agomeda areas. A large portion of vegetation remains dry for most parts of the year particularly towards the south except for the short rainy season. Ancient igneous rocks underlie the major part of the district with strongly metamorphosed ancient sediments occurring along the western boundary. The predominant soil types in the district are the black clays classified as Akuse series and occupies the central to eastern parts of the district. The soils are highly elastic when wet but become hard and compact when dry and then crack vertically from the surface. This renders the soil unsuitable for hand cultivation. The Yilo Krobo district is approximately between latitude 60° 00’ and 00° 30’ North and between longitude 00° 30’ and 10° 00’ West. It covers an estimated area of 805 km2, constituting 4.2% of the total area of the Eastern Region with Somanya as its capital. The Yilo Krobo district is bounded in the north and east by Lower Manya Krobo District, in the South by Akuapim North District and on the West by New-Juaben Municipal District, East Akim Municipal District and Fanteakwa District. Manya Krobo District lies between latitude 06° 05’ South and 06° 30’ North and longitude 00° 08’ East and 0° 20’ West. The Administrative Capital of the district is Odumase Krobo. It covers 37    University of Ghana http://ugspace.ug.edu.gh   an area of 1,476 km, constituting about 8.1% of the total land area within the Region (18,310 km). The District shares Boundaries with Upper Manya Krobo District to the north, to the south with Dangme West and Yilo Krobo respectively, and to the east with Asuogyaman District. Figure 2 is a map showing the three districts where the study was conducted.   Shai Osudoku Figure 2. Map showing the Shai Osudoku, Manya and Yilo Krobo districts where the study was conducted   3.1.3. Description of the Study Farms This work was carried out in three commercial mango farms. All the three farms i.e. Bismark Adu Farms (Ayikuma), Sabano Farms (Somanya) and Hydrotech Farms (Kpong) are all GlobalGAP certified. Sabano Farms is located between latitude 06° 04’ and 06° 55’ West and 06°  4’ and 8° 10’ North; longitude 00° 00’ and 06° 63’ North and 00° 00’ and 5° 72’ West with an 38    University of Ghana http://ugspace.ug.edu.gh   elevation of between 65.2-79.6m above sea level. The orchard covers 13 hectares of land with a planting distance of 10m x 10m. The common varieties cultivated among the three orchards include ‘Keit’, ‘Kent’, ‘Palmer’, ‘Haden’ and ‘Irwin’. Pest management practices common to all the farms were chemical control (use of synthetic pesticides) and cultural control (picking and destroying dropped fruits). Among the common pesticides used in all the orchards were deltamethrin, acephate and carbaryl. A total of 3-6 applications are made within the season depending on the farm size and infestation of the insects. Spraying of pesticides is not carried out two weeks before harvesting. Weed control was usually done through the use of herbicides and is done between 2-4 times in each fruiting season. In addition, an appreciable level of soil management is administered in Hydrotech Farms.   3.2. Field Evaluation of Traps and Lures 3.2.1. Duration of Study: This study was conducted from June 2014 to June 2015 in three mango orchards in Southern Ghana. 3.2.2. Trap Deployment Two trap types (Black pyramid and Circle traps) baited and unbaited with two attractants namely benzaldehyde, and essential oil (extracted from mango flowers by cold percolation using petroleum ether, ethyl acetate and ethanol) were evaluated for their effectiveness in capturing the mango stone weevil. Pyramid traps (Plate 5) were located near the interior of a tree canopy about 0.6 m from the tree trunk. Circle traps, with a masking tape for attachment were wrapped at random around the main tree trunk of the trees selected for trap placement. A total of 96 traps were used, comprising 48 of each trap type. The Black pyramid traps were purchased from Great 39    University of Ghana http://ugspace.ug.edu.gh   Lakes IPM Inc. Vestaburg, MI; while the Circle traps were constructed at the Forest and Horticultural Crop Research Centre (FOHCREC), Kade. Traps were set up in a Randomized Complete Block Design (RCBD) where each orchard was divided into four blocks and the Circle and the Black pyramid traps in combination with the following treatments; Control, Benzaldehyde (BZ), Essential Oil (EO), and Essential Oil + Benzaldehyde (EO + BZ) randomized per block in each orchard. The Black pyramid traps were placed 60 cm away from a mango tree trunk and incisions were nailed to the ground with plastic pegs for firmness. Plates 5 and 6 show the deployment of the Black pyramid traps and Circle traps in the field.   Plate 5. Pegging (left) and placement (right) of the Black pyramid traps in the field 40    University of Ghana http://ugspace.ug.edu.gh       Plate 6. Circle trap (left) with a lure and (right) without a lure deployed in the field. Red arrow indicates how weevils enter the trap The traps (or trapped trees) were separated by three untrapped trees, yielding a total distance of 30m between each trap. Trap deployment for each season began at the onset of the season. Traps were inspected twice in a month for MSW and other insects until there was clear reduction in insect numbers indicating the end of the season. Counting and recording of the number of the weevils captured per trap was done and continued throughout the fruiting season. Although the focus of the study was the weevil, records were also taken on other related insects and non-target beneficial insects (i.e. ladybird beetles, ants, wasps, lacewings, bees etc.) that entered the traps either actively or passively to determine trap efficacy and selectivity. 41    University of Ghana http://ugspace.ug.edu.gh   3.2.3. Lure Treatments The lures evaluated involved one essential oil which was extracted from mango flowers and another known synthetic fruit volatile (benzaldehyde). In each district, one mango orchard was selected. Randomized Complete Block Design (RCBD) was used where each orchard was divided into four blocks and the circle and pyramid traps in combination with the following treatments; Control, Benzaldehyde (BZ), Essential Oil (EO), and Essential Oil + Benzaldehyde (EO + BZ), assigned randomly to each experimental unit. From the date of first weevil capture, the traps and lures in each block were re-randomized, and this continued every month until the end of the season. The re-randomization of the traps and lures monthly ensured that location effect was minimized. For each of the baited traps, a single dispenser containing ~5 mL of benzaldehyde and/or essential oil was deployed in small polyethylene vials placed inside the plastic, funnel shaped top attached to the tip of each trap. Plate 7 shows the extraction process while Plate 8 shows some quantities of essential oils extracted from the mango flowers.   Plate 7. Extraction (cold percolation) of essential oils 42    University of Ghana http://ugspace.ug.edu.gh     Plate 8. After extraction   3.3. Effect of Air Temperature and Relative Humidity on Trap and Lure Performance The effect of air temperature and relative humidity on performance of traps and lures were investigated by correlating the number of stone weevils captured in each lure and trap combination to determine which of the factors influenced the weevil numbers. To accomplish this, two data loggers were placed in two of the farms (Ayikuma and Somanya) and programmed to record the temperature and relative humidity every thirty minutes for the major mango fruiting season. The two orchards were selected based on availability and unavailability of water in the orchards. The orchard in Somanya is generally very dry compared with the orchard in Ayikuma which has patches of water within the orchard. So the data logger was placed closer to water in Ayikuma. Plate 9 is a data logger placed in one of the mango orchards. 43    University of Ghana http://ugspace.ug.edu.gh     Plate 9. Data logger placed in one of the mango orchards where the study was conducted 3.4. Release Rate of Lures The release rates of the lures were determined gravimetrically in the orchards. The essence of this is that, the amount of lure released usually correlates with capture of insects. Whereas some insects may respond to high doses others may require low doses. This experiment was conducted from 5 February to 12 May, 2015 in an experimental mango orchard at FOHCREC, Kade. The aim was to evaluate the release rates 1 mL/hr of each lure. The vials were obtained from VWR Scientific Products; Boston, MA. All vials containing BZ and EO were replaced on February 15, 2015 and experiment was repeated. For each formulation, the release rate was determined by weight loss by day. Each treatment was replicated 5 times. Prior to this the initial weights of the lures were taken. This was used to determine the release rate per day under the variable weather 44    University of Ghana http://ugspace.ug.edu.gh   conditions in the mango orchard. This was repeated in the laboratory to compare the release rates at constant temperatures.   Plate 10. Containers used for the release rate of EO and BZ 3.5. Fruit Damage Assessment During the Major and Minor Mango Fruiting Season Damage assessments were conducted during each mango season to determine whether damage correlated with trap capture. Thirty fruits each were harvested at random in addition to thirty dropped fruits from each of the tagged trees in the major season and fruits inspected for MSW damage (arising from feeding and oviposition) by dissecting the seeds. However, due to poor fruiting during the minor mango season, unequal numbers of fruits were dissected. The percentage fruit damage was determined by dividing the number of fruit damaged by the total number of fruits picked and value multiplied by 100. Plate 11 shows the processes involved in fruit dissection during damage assessment. 45    University of Ghana http://ugspace.ug.edu.gh   z   Plate 11. Fruit cutting, seed opening and checking for MSW in seed Plate 12. MSW larvae (arrowed) in a matured fruit 46    University of Ghana http://ugspace.ug.edu.gh   Adult Pupa   Plate 13. Adult (black) and pupa (white) in an immature mango fruit The phenological stages of the mango crop in the 2014-2015 mango growing season was recorded and presented in the Table 3 below. Table 3. Description of the phenological stages of the mango crop from July 2014-June 2015 Stage Full Meaning Period Covered VG 2 Vegetative growth (minor season) July 7th - July 28th (weeks 1-4) B 2 Blooming (minor season) August 4th - September 1st (weeks 5-9) FS 2 Fruits set (minor season) September 8th - September 22nd (weeks 10-12) FD 2 Fruit development (minor season) September 29th - November 10th (weeks 13-19) FM 2 Fruit maturity (minor season) November 17th - December 15th (weeks 20-24) VG 1 Vegetative growth (major season) December 22nd - January 5th (weeks 25-27) B 1 Blooming (major season) January 12th - February 9th (weeks 28-32) 47    University of Ghana http://ugspace.ug.edu.gh   FS 1 Fruit set (major season) February 16th - February 23rd (weeks 33-34) FD 1 Fruit development (major season) March 2nd - April 27th (weeks 35-43) FM 1 Fruit maturity (major season) May 11th - June 15th (weeks 45-50) 3.2 Statistical Analyses The data units for the field experiments were number of MSW captured/trap / sampling date and damage due to MSW feeding and oviposition for both the major and minor mango seasons. The trap captures and percentage fruit damage were transformed where necessary by using (x + 0.5)1/2 and Arcsine (x + 0.1)1/2 respectively, when the assumptions of ANOVA were seen to have been violated. Data were first analyzed using standard least square analyses of variance to determine the effects of sampling date, lure type, location and trap type and their interactions. Treatments which showed significant effects and their interactions were further analyzed either by a Student’s t-test (two treatments only) or analysis of variance (ANOVA; more than two treatments) using JMP version 10.0 (ANOVA, JMPIN version 10.0, SAS Institute, 2010) for each orchard for both seasons. Data on release rates were also analyzed using Student’s t- test. The date of first weevil capture was noted for each trap. Seasonal mean captures and damage were compared by using analysis of variance (ANOVA, JMPIN version 7.0, SAS Institute, 2006) to test for the effects of treatment (trap types), lure types and block (replicates) and their interactions. Significant differences were established at the 95% confidence level (P < 0.05). Means were separated by Tukey-Kramer HSD. 48    University of Ghana http://ugspace.ug.edu.gh   CHAPTER FOUR RESULTS 4.1. General Trap Performance The standard least square ANOVA (Appendix 1) showed significant differences among the locations (F = 3.89, d.f. = 2; P = 0.0248), trap type (F = 5.55, d.f. = 1; P = 0.0212), lure type (F = 3.21, d.f. = 3; P = 0.0281) and the interaction between trap type and lure type (F = 3.6, d.f. = 3; P = 0.0174). However, the interaction between location*trap type (F = 1.49, d.f. = 2; P = 0.2326,), location*lure type (F = 0.98, d.f. = 6; P = 0.4463) and location*trap type*lure type (F = 1.45, d.f. = 6; P = 0.2072) were not significant. Because the interaction of trap type and lure was significant, a one way ANOVA was performed on the lure and trap type without recourse to location since both location and trap type, and location and lure type was not significant. The one way ANOVA of the trap type was irrespective of location. The results showed that trap type was significant. Pyramid trap captured significantly more weevils than the Circle trap. Although not significant, the control recorded numerically more weevils compared with the other treatments. On the whole a total of 14 stone weevils were recorded by the various trap and lure combinations in all the three study sites. A total of 10 (71.4%), 4 (28.6%), and 0 (0%) weevils were recorded in Kpong, Ayikuma, and Somanya, respectively. 49    University of Ghana http://ugspace.ug.edu.gh   4.2. Trap and Lure Performance 4.2.1. General Performance of Traps across the Study Locations 0.45 0.4 a 0.35 0.3 0.25 0.2 0.15 0.1 0.05 a 0 Circle Pyramid Trap Type   Figure 3. A graph comparing the mean trap catches between Circle and pyramid traps used in Ayikuma. t = 2.84; d.f. = 1, 27; P = 0.10 The performance of traps in Ayikuma did not show any significant difference between the Circle and the pyramid trap in terms of mean trap catches (P > 0.05). The Circle trap recorded no stone weevil in Ayikuma throughout the nine month period. Even though the pyramid trap captured some of the stone weevils, the numbers were not significant. 50    Mean Trap Catches University of Ghana http://ugspace.ug.edu.gh   0.8 a 0.7 0.6 0.5 0.4 a Circle 0.3 Pyramid 0.2 0.1 0 Circle Pyramid Trap Type   Figure 4. A graph comparing the mean trap catches between the circle and pyramid traps in Kpong. t = 1.57; df = 1, 27; P = 0.22 The mean trap catches for both the circle and the pyramid traps in Kpong did not show any significant difference (P > 0.05) with regard to trap performance. Though both traps recorded some stone weevil catches, the numbers were not significant. In Somanya both the circle and the pyramid traps did not record any stone weevil throughout the study period. 51    Mean Trap Catches University of Ghana http://ugspace.ug.edu.gh   4.2.2. Performance of Traps in Combination with Four Treatments 0.35 a 0.3 0.25 0.2 0.15 0.1 0.05 a a a 0 BZ Control EO EO+BZ Treatments   Figure 5. A graph showing mean (± SE) trap catches for the circle trap in combination with the four treatments in all the study areas. The mean trap catches for Circle trap in combination with the four treatments did not show any significant difference. However a combination of circle trap and Benzaldehyde (BZ) produced the highest in terms of mean trap catches. 52    Mean (± SE) Trap Catches University of Ghana http://ugspace.ug.edu.gh   1.2 a 1 0.8 BZ 0.6 Control EO 0.4 ab EO+BZ ab 0.2 b 0 BZ Control EO EO+BZ Treatments   Figure 6. A graph showing the mean trap catches for the pyramid trap in combination with all the four treatments in all the study areas. Mean trap catches recorded for the pyramid trap in combination with the four treatments used in the study showed a significant difference in mean trap catches. A combination of the pyramid trap and control was significantly different (P < 0.05) than the mean trap catches for the combination between the pyramid trap and essential oil (EO). The remaining two treatments; BZ and EO+BZ in combination with the pyramid trap did not show any significant difference in trap catches.   53    Mean Trap Catches University of Ghana http://ugspace.ug.edu.gh   4.2.3. Performance of the Individual Trap Types in All the Three Study Locations 0.3 a 0.25 0.2 0.15 0.1 0.05 a a 0 Ayikuma Kpong Somanya Study Areas   Figure 7. A graph showing the mean (± SE) trap catches of the circle trap in all the three study areas From the study, even though the performance of the circle trap across the three study areas did not show any significant difference (P > 0.05) in the mean trap catches, the highest mean trap capture was recorded in Kpong while in both Ayikuma and Somanya, zero mean trap catches was recorded. 54    Mean Trap Catches University of Ghana http://ugspace.ug.edu.gh   0.8 a 0.7 0.6 0.5 a 0.4 Ayikuma Kpong 0.3 Somanya 0.2 0.1 a 0 Ayikuma Kpong Somanya Study Areas   Figure 8. A graph showing the mean (± SE) trap catches of the pyramid trap in all the three study areas. Mean trap catches recorded for the pyramid trap across all the three study areas did not show any significant difference (P > 0.05). Even though no significant difference was found among the three study areas, numerically the pyramid trap captured more stone weevils in Kpong (mean: 0.50±0.24) compared with Ayikuma. However, no stone weevil was recorded in the pyramid trap in Somanya. 55    Mean (± SE) Trap Catches University of Ghana http://ugspace.ug.edu.gh   4.2.4. Performance of Treatments Across the Study Locations 0.7 a 0.6 0.5 0.4 BZ Control 0.3 a EO EO+BZ 0.2 0.1 a a 0 BZ Control EO EO+BZ Treatments   Figure 9. A graph showing mean (± SE) trap catches of the four treatments used in Ayikuma. From the results gathered, mean insect trap catches recorded for all the four treatment used in the study did not show any significant difference (P > 0.05) in Ayikuma. Even though no significant difference was found among treatments used in Ayikuma, the Control numerically captured more stone weevils (mean: 0.38±0.25) followed by Benzaldehyde (mean: 0.13±0.13) compared with Essential oil (EO) and a combination of Essential Oil and Benzaldehyde (EO+BZ) which recorded zero catches. 56    Mean (± SE) Trap Catches University of Ghana http://ugspace.ug.edu.gh   1.4 a 1.2 1 0.8 BZ a Control 0.6 EO 0.4 EO+BZ a 0.2 a 0 BZ Control EO EO+BZ Treatments   Figure 10. A graph showing mean (± SE) trap catches of the four treatments used in Kpong. The performance of the four treatments in Kpong did not show any significant difference in terms of trap catches. The highest mean trap capture was recorded in the control; followed by Benzaldehyde (BZ), and then a combination of Essential Oil and Benzaldehyde (EO+BZ). All the four treatments used in Somanya recorded a mean trap capture of zero (0); and there was no any significant difference between the treatments. 57    Mean (± SE) Trap Catches University of Ghana http://ugspace.ug.edu.gh   4.3. Average Weekly Temperature and Relative Humidity During the Major Mango Fruiting Season in Somanya Average Weekly Temperature and Relative Humidity during the Major Mango Fruiting Season 90 80 70 60 50 Temperature ( °C) 40 30 Relative Humidity (%) 20 10 0   Figure 11. A graph showing the weekly average temperature and relative humidity during the major mango fruiting season Temperature and relative humidity were fairly constant throughout the fifteen weeks of study (Figure 11). An average weekly minimum temperature of 25°C and a maximum of 30.2°C were recorded in week one and week fifteen respectively. Average weekly relative humidity increased from 56.9% to 81.8% within the first three weeks and then remained fairly constant to the last week of study. The maximum relative humidity (85.5%) was recorded in week eleven and the minimum humidity (56.9%) in the first week. 58    University of Ghana http://ugspace.ug.edu.gh   However, throughout this period there wasn’t any trap catches. Therefore both temperature and relative humidity could not be correlated with trap and lure performance. 4.4. Release Rates of Lures The results from the release rate showed that there was significant difference between the release rates of the EO and BZ when placed in the field (t = 8.72, d.f. = 1, 4, P = 0.0419). There was however no significant difference observed between the release rates of EO and BZ when placed together in the laboratory (t = 1.53, d.f. = 1, 4, P = 0.2835). Table 4. Release rates of the benzaldehyde and essential oils under field (only pyramid trap) and laboratory conditions Treatment Mean (± SE) (field) mg/hour Mean (± SE) (Lab) mg/hour EO 2.18 ± 0.06 b 1.48 ± 0.13 BZ 2.55 ± 0.06 a 1.80 ± 0.13 NS BZ = commercial benzaldehyde lure; and EO = Essential oil. Means having no letter in common are significantly different (Student’s t- test P < 0.05; n = 5). NS means not significant 59    University of Ghana http://ugspace.ug.edu.gh   4.5. Fruit Damage Assessment   100 90 Ayikuma Somanya 80 Kpong 70 60 50 40 30 20 10 0 Minor season Major season   Figure 12. The mean percent damage of mango fruits in all the three study areas during the major and minor mango fruiting season. Damage was generally higher during the minor season with mean percent damage of 92.9%, 33.3%, and 54.5% for Ayikuma, Somanya and Kpong, respectively (Figure 12). The same trend was observed during the major season. However, damage was relatively low during the major season compared to the minor season with mean percent damage of 20%, 1.7%, and 10% for Ayikuma, Somanya and Kpong respectively. Fruits which were considered damaged either had weevils in the seed or showed signs of earlier attacks like destroyed seeds and exit holes. During the minor season, a maximum of five or six adult weevils were found in a single fruit. In some cases the larvae, pupa and adult weevils were found in a single fruit. The situation was different 60    Mean percent damage University of Ghana http://ugspace.ug.edu.gh   during the major mango fruiting season where most of the fruits dissected had only a single weevil. Seasonal Occurrence of MSW throughout the Study Period 8 7 6 5 4 3 2 1 0 Trap Inspection Dates   Figure 13. A graph showing the seasonal occurrence of the mango stone weevil in all the study areas during the 2014 mango fruiting season   61    Trap Catches 4-Aug 18-Aug 1-Sep 15-Sep 29-Sep 13-Oct 27-Oct 10-Nov 24-Nov 8-Dec 22-Dec 5-Jan 19-Jan 2-Feb 16-Feb 2-Mar 16-Mar 30-Mar 13-Apr University of Ghana http://ugspace.ug.edu.gh   CHAPTER FIVE DISCUSSION 5.1 Trap and Lure Performance The results from this study have shown that the Black pyramid trap captured more of the stone weevils than the Circle trap in the different locations. The pyramid trap captured about 6-fold of the stone weevils compared to the Circle traps. This was not surprising, as research conducted earlier showed that the Black pyramid trap was significantly more effective in capturing plum curculios than circle traps (Johnson et al., 2002; Akotsen-Mensah et al., 2010). The pyramid trap is believed to provide an attractive visual stimulus by mimicking a tree trunk (Tedders & Wood, 1994; Mulder et al., 1997). The Black pyramid traps also have white vertical lines at the edges which reflect light at night and are made to mimic the tree trunk as the first dark object that is seen by the adult weevils upon emergence; and are percieved as trees by the weevils. This result confirms that of Tantoh (2014) who showed that among four traps tested, the pyramid trap came out as the best. Although in Tantoh’s study no attractants were added, the Black pyramid trap consistently recorded the highest number of stone weevils (Tantoh 2014). In the current study, two attractants (benzaldehyde and essential oils) were added to determine if trap performance could be improved. The results however, indicated that the lures did not significantly increase the trap numbers compared with the data obtained by Tantoh (2014). It was expected that the trap captures would be significantly improved by addition of the benzaldehyde and essential oils but this was not the case. Our selection of benzaldehyde as a potential attractant was informed by literature that benzaldehyde is a major component found in most fruits (Prokopy et. al., 2000; Leskey et al., 2001) and as a result it was hypothesized that the mango stone weevil could be 62    University of Ghana http://ugspace.ug.edu.gh   attracted to this ubiquitous compound. As already indicated, the results from this study did not provide enough evidence to support this hypothesis. Preliminary investigation in the laboratory however had provided some evidence of the weevil being marginally attracted to benzaldehyde (Akotsen-Mensah et al., unpublished). The field trial evaluating the synthetic compounds in association with the traps did not provide the evidence that mango stone weevil could either be attracted to single components of benzaldehyde or essential oil from the mango inflorescence or their combinations. Pyramid and Circle traps with lures (benzaldehyde, grandisoic acid and plum essence) evaluated by Akotsen-Mensah et al., (2010), in Alabama peaches revealed a significant increase in trap capture in the number of plum curculios. Leskey and Wright (2004a) found that plum curculio were only attracted to traps baited with aggregation pheromone and benzaldehyde in apples. It has been reported that the mango stone weevil prefers the flower part of the mango plant to other parts in a research conduced by Braimah and Van Emden (2010) with arena and olfactometer bioassays. Combination of these two lures was also done to ascertain their effectiveness. Attractants used for trials on insect capture comes in different forms such as; pheromones, food baits, essential compounds from host plants and other chemically synthesized compounds. Depending on associated factors such as existing environmental conditions, release rates of the attractant, the combination with which attractants are used such as traps and the chemical composition of the attractants, attractants have given off varying performances in separate trials. Work conducted by Pinero and Prokopy in 2003, on field evaluation of plant odor and pheromonal combinations for attracting plum curculios revealed that increasing the release rate of Grandisoic acid from 1 to 2 mg/d in combination with benzaldehyde resulted in increased 63    University of Ghana http://ugspace.ug.edu.gh   captures. From their work, they inferred that an increase in the release rate of attractants resulted in an increase in trap capture and vice versa. In a study conducted by Hoffmann et. al. (1996), sticky traps baited in combination with an attractant TIC (1,2,4-trimethoxybenzene, indole, and trans-cinnamaldehyde) and sticky traps without any attractant, were evaluated to assess their efficacy in capturing striped cucumber beetle, spotted cucumber beetle, western corn rootworm, northern corn rootworm, cucumber beetle, and western spotted cucumber beetle. All the above listed insects are pests of curcubits. The study was carried out on a comparative basis between two separate trials in New York and California. The results from the trial indicated that the baited sticky traps captured more insect species than the unbaited sticky traps in both locations. They also observed from their work that the response time of the insect species in the trial to the attractant TIC varied greatly with the time of the day with the greatest response occurring around midday (Hoffman et al., 1996). A related work was carried out in Texas by Lance et. al. (1992). Their work involved using a field of maize to evaluate responses of Mexican corn rootworm beetles to ten volatiles that are known attractants of other rootworm beetles. Traps baited with 100 mg of any of the attractants captured significantly more male and female than did unbaited traps, but the increase in capture was greater for female beetles than for males. Traps baited with a 1:1:1 mixture of 1,2,4 trimethoxybenzene, indole and cinnamaldehyde ("TIC") captured the greatest number of females (a 50-fold increase over capture on unbaited traps) but did not capture significantly more beetles than traps baited with a 1:1:1 mixture of veratrole, indole and phenylacetaldehyde ("VIP") or with indole alone (Lance et. al., 1992). 64    University of Ghana http://ugspace.ug.edu.gh   Of the three study areas where this research was carried out, there was no significant difference between the Black pyramid and the Circle traps in Ayikuma, Kpong and Somanya respectively. However, there were significant differences among the locations, trap type, lure type and the interaction between trap type and lure type. Even though these traps have been reported to have high trap catches for the plum curculio and the pecan weevil in other cropping systems, results from this work proved otherwise probably because this work was carried out in the tropical zone while that of the plum curculio and the pecan weevil were conducted in the temperate zone. The temperate zone has four climatic seasons as compared to the tropical zone with only two climatic seasons. In addition, temperature and humidity in the tropics are always higher compared to the temperate regions eventhough some of the countries within the temperate zone sometimes become extremely humid at certain times in the year. Mean trap catches recorded for the pyramid trap in combination with the four treatments used in the study showed a significant difference in mean trap catches. A combination of the pyramid trap (control) was significantly different as compared to the mean trap catches for the combination between the pyramid trap and essential oil (EO). The pyramid trap in combination with the other two treatments; BZ and EO+BZ however did not show any significant difference in mean trap catches in all the three study areas. The performance of both the circle and the pyramid traps in all the three study areas did not show significant difference in mean trap catches. Even though Kpong recorded the highest trap catches for both circle and pyramid traps, weevil numbers were very low and far below expectation. 65    University of Ghana http://ugspace.ug.edu.gh   One major possibility for the poor performance of the traps in this work was probably due to the fact that all three locations where the research was conducted were managed with insecticides. These orchards resort to intensive spraying activities as the most dominant management strategy for the mango stone weevil. It was observed throughout the study period that anytime these orchards were visited, there was spraying activities being carried out by the farmers even though they claimed spraying was done between 3-6 times in a fruiting season. Spraying has been observed to hinder the movements of the mango stone weevils and reduce their activities (Tantoh, 2014). According to farmers, continuous spraying of mango orchards reduces infestation levels of the mango crop by the stone weevils and results in bumper harvests. Chemical control can be used to reduce mango stone weevil populations to low levels especially if weevil eggs are detected (Personal communication). One or two targeted sprays at the start of egg-laying can be used to kill adult weevils thereby reducing their population. More so, in Somanya where there was no trap capture throughout this work, it was observed that the farmer introduced Oecophylla longinoda (red weaver ants) which invaded more than 70% of the mango trees as a control strategy in addition to the use of chemicals. Braimah and van Emden (2010) reported that, Oecophylla longinoda and Oecophylla smaragdina are the most promising indigenous generalist predators of the mango stone weevil. The use of weaver ants have been observed to be effective for reducing infestation of fruits by the weevils and other pests (Van Mele & Vayssieres, 2007). Green ants have been used as generalist predators in Asia in the management of mango stone weevils. According to Peng and Christian (2007), treatment with weaver ants plus chemicals produced lower levels of downgraded fruits (< 0.5%) compared to the treatment with chemical insecticides (1.4-2.1%). In three insecticide-free orchards, fruits 66    University of Ghana http://ugspace.ug.edu.gh   were much less damaged on trees with weaver ants (< 1%) than on trees without the ants (2.5- 15.7%). Peng and Christian (2007), found Oecophylla smaragdina to be an effective biocontrol agent and advised that keeping their populations high will ensure successful control of the stone weevil. This probably accounted for the zero trap capture in Somanya throughout the study. Another possibility for the poor performance of the traps may be due to low populations of mango stone weevils in the study areas. In a research conducted by Leskey et al. (2005) on nonfruiting host tree volatile blends as novel attractants for the plum curculio, it was found that an increased population density accounted for higher trap captures. Research has shown that volatiles released by host plants are as attractive as single fruit-based synthetic attractants. Therefore when the concentrations of these host plant volatiles are higher than synthetic odor baits in an orchard, the synthetic baits may be rendered less attractive by the weevils. There was a significant impact of host apple trees on plum curculios behavior to baited traps, further strengthening the hypothesis that olfactory cues produced by host trees particularly after fruit set, are more attractive to plum curculios than synthetic attractants (Leskey & Wright, 2004b). This may have accounted for the very low population of stone weevils captured by the baited traps in this study. Single-component fruit-based attractants may not be very competitive within the context of an orchard, particularly when the attractant itself also is released by developing fruit. The volatile release of benzaldehyde and other compounds by host trees contributed to reduction of plum curculio captures in benzaldehyde baited traps when traps were in close proximity to host trees (Leskey & Wright, 2004b). This probably accounted for the inability of the essential oils alone in combination with the circle and pyramid traps to capture 67    University of Ghana http://ugspace.ug.edu.gh   any mango stone weevil throughout the study period. Essential oils have been extracted from mango flowers, and thus, the degree of competition from natural sources of olfactory stimuli, i.e., host mango trees, will likely be greater if baited traps are deployed within a mango orchard. Also the essential oil did not work perhaps because it was just a crude extract. Crude extracts have various components; some of which may either be attractants or repellents. The essential oil will be further analysed by GC-MS to determine the actual compounds present in the EO. These compounds will be tested in a four-chambered olfactometer to ascertain which compound/compounds present in the EO are attractants or repellents so that their synthetic components could be produced and used in subsequent research. It has been established that insects captured by the pyramid traps can escape from the trap tops especially if regular monitoring is not carried out. Hogmire and Leskey (2006), reported that improved trap for monitoring stink bugs in apple and peach orchards in West Virginia, the black pyramid traps recorded very low trap catches due to escape of the stink bugs from the pyramid traps. A similar work conducted earlier by the same authors revealed that 58% of female and 67% of male brown stink bugs had escaped from the pyramid trap after 7 days; and resulted in low trap catches (Leskey & Hogmire, 2005). In this work, trap monitoring was done every two weeks; within this two weeks interval stone weevils captured by the pyramid traps may have escaped from the traps and this probably accounted for the very low stone weevil numbers recorded in the pyramid traps. Indeed a preliminary tested found out that when temperatures are high weevils can escape from the trap in 48 hours (Akotsen-Mensah et al., unpublished) 68    University of Ghana http://ugspace.ug.edu.gh   5.2. Fruit Damage Assessment During the Major and Minor Mango Fruiting Season The results from this study have shown that fruit damage during the major mango was generally low compared to the minor season. The highest damage was recorded at Ayikuma followed by Kpong and then Somanya. From the survey it was observed that trap captures did not have direct correlation with fruit damage, since low numbers recorded did not show less damage. For instance only 4 (92.9%) and 10 (54.5%) stone weevils were captured by the traps in Ayikuma and Kpong respectively (Figure 12). Stone weevil damage range to fruits has previously been reported to be 46 - 93% (Shukla et al., 1985). The high level of stone weevil damage during the major mango season may be due to a number of factors. Firstly, the orchard management adopted by the farms may have accounted for the high infestation levels. For example, the orchard in Somanya was better managed in terms of timely application of control interventions like spray of insecticides, pruning of the trees, weed control under the orchard understorey etc. as compared to the other two and as a result no or little damage were recorded in this orchard. Secondly, the low damage recorded during the major season may probably be due to the intensive spraying of the orchards by farmers at least between 3-6 times during fruiting after realizing damage was higher during the minor season. A number of insecticides have been evaluated for control of the adult mango stone weevils, especially during flowering and fruiting of the crop (Balock and Kozuma, 1964). Some of the insecticides that have been effective in mango stone weevil management include Acephate, thiamethoxan, carbaryl, deltamethrin, dimethoate, endosulfan, ethofenprox, fenthion, fenvalerate, imidacloprid, monocrotophos and prothiofos. The application of these chemicals at least twice each during flowering and early fruiting, have been effective in reducing populations of the weevil and infestation of fruits (Shukla and Tandon, 1989; Nel et al., 2002; Verghese et al. 69    University of Ghana http://ugspace.ug.edu.gh   2005b). A research conducted by Verghese et al., (2005b) revealed that Acephate, deltamethrin, carbaryl and ethofenprox reduced infestation levels from 33% to between 3.3% and 14%. Because farmers used some of these insecticides and obtained low fruit damage, it was not surprising to find that damage of the weevil were low in the orchards where these insecticides were applied. According to the farmers sometimes a combination of two or more of these chemicals are used for effective control; and that was exactly what took place during this study just before the beginning of the major season. The frequency of spraying activities depends on the percentage of damage assessed. The higher the damage assessed in a particular fruiting season, the higher the frequency of spraying activities in the next fruiting season (Personal observation). It is also worth to note that, the 2014 mango fruiting season experienced a change in the phenology of the mango crop (Table 3) from the 2013 mango fruiting season (Tantoh, 2014). The 2014 minor fruiting season generally experienced very low fruiting. The low fruiting was due to sensitivity to weather conditions and the diurnal bearing property of the mango tree. Farmers attributed low fruiting to the early rains accompanied by heavy storms that washed away large quantities of the mango flowers. As a result of this, farmers were left with very little mango flowers in their orchards hence low fruiting and therefore were very reluctant to freely give out flowers and fruits used during this work. This made it very challenging getting mango flowers for extraction of the essential oil as one of the major lures used in this work; and mango fruits for damage assessment. However during the major fruiting season though flowering was delayed, there was abundance of fruits. Singh and Kushwaha (2006 ) found that in dry tropical trees, the duration of fruiting phenophase depended at least to some extent, on the time of flowering and the leafless period during the annual cycle; species with longer fruiting duration, flower in the 70    University of Ghana http://ugspace.ug.edu.gh   hot-dry summer and take full advantage of rainy season for fruit development in India. Fruiting duration may impose a constraint on flowering time (Fenner, 1998). In a related work, Primach (1985) reported that species with larger fruits (requiring a longer time for fruit development) flowered earlier than species with small fruits. Although fruiting duration is related to flowering time, fruit type is independent of flowering time, especially in species flowering during the dry part of the year (Singh & Kushwaha, 2006). During the study, a maximum of five or six adult weevils were found in a single fruit in some cases during damage assessment in the minor season. This number conforms to what was reported by Braimah et al. (2009) in Southern Ghana; where in one case, as many as six weevils were found in a single fruit. Tantoh (2014) observed that fruits with multiple weevil numbers had relatively small weevil sizes. However, during this study, fruits with multiple infestations had relatively larger weevil sizes as compared to weevils in single fruits infestations though the study was carried out in the same agro-ecological zone in Ghana (Personal observation). 5.3. Effect of Temperature and Relative Humidity on Trap and Lure Performance Temperature and relative humidity could not be correlated with trap and lure performance due to zero trap catches throughout the major mango fruiting season when the data loggers were sent to the study areas. Therefore the effect of these two parameters on trap and lure performance could not be determined in this work. However, environmental parameters have been reported to have an influence in one way or the other on activity patterns of the mango stone weevil. The effect of temperature has been observed in the rapid degradation of the volatile lure constituents resulting 71    University of Ghana http://ugspace.ug.edu.gh   in reduced effectiveness as disproportionate loss of a single lure component can render these compounds behaviorally undetectable (Bartelt et al., 1999). Only a few proportions of curculios that do fly alight on pyramid traps; a great majority bypasses the traps in flight when evening temperatures are moderate; Curculios may fly directly into tree canopies when temperature is high (Prokopy & Wright, 1997). There is a relationship between the relative humidity within any given environment and infestation levels of fruits; infestation levels are higher when relative humidity is higher (Braimah et al., 2009). When relative humidity increased, weevil emergence increased in a research conducted by Louw (2009) in South Africa. An average temperature of 28 oC and relative humidity of 72.77% have been found favourable for the longer life cycles whereas the average minimum temperature of 26.43 oC with 74.66% relative humidity have been observed to shorten their life cycle (Devi, 2007). Balock and Kozuma (1964) reported that egg hatching increased when temperatures increased between 65- 86°F (18.3-30°C). Work conducted by Kasap et al. (2009) on the activity patterns of sand fly species and comparative performance of different traps in an endemic Cutaneous Leishmaniasis (Kasap et al., 2009) revealed that the most important factor affecting sand fly activity was low relative humidity, followed by low wind velocity and high temperature. 72    University of Ghana http://ugspace.ug.edu.gh   5.4. Release Rates of Lures The release rates of benzaldehyde (BZ) and essential oils (EO) showed significant differences when they were determined in the field. However no significant differences were observed when the release rates of EO and BZ were determined in the laboratory (Appendix 13). The volatile release of EO was found to be faster than BZ both in the field and the lab. Benzaldehyde was determined to be released at a rate of 2.55mg/h and 1.80mg/h in the field and lab respectively; whereas the volatile releases of the Essential oils were found to be 2.18mg/h in the field, and 1.48mg/h in the laboratory. Even though there was significant difference between the release rates from Benzaldehyde (BZ) and Essential oils (EO) during the field determination; this result did not affect trap capture when the 2 were used as attractants in combination with the traps.                       73    University of Ghana http://ugspace.ug.edu.gh   CHAPTER SIX CONCLUSIONS AND RECOMMENDATIONS 6.1. Conclusions Even with addition of the lures, the traps still recorded very low mango stone weevil numbers far below expectation in this research. Of the two trap types evaluated, the pyramid trap performed better by capturing more of the stone weevils compared to the Circle trap in all the study areas. The study showed significant differences among the locations, trap type, lure type and the interaction between trap type and lure type. The interaction however, between location*trap type, location*lure type and location*trap type*lure type were not significant. The highest trap capture was recorded in Kpong followed by Ayikuma. There was no trap capture in Somanya throughout the study period. The study also revealed that the orchard in Somanya was managed well compared with the orchards in Kpong and Ayikuma. Fruit damage was higher at Ayikuma followed by Kpong and Somanya, respectively. The damage in the orchards in Kpong and Ayikuma fell within the range reported by Shukla et al., 1985. The study also revealed that trap numbers do not have a direct correlation with fruit damage. The effect of temperature and humidity on trap and lure performance could not be determined in this work due to zero trap capture during the major mango fruiting season. The very low mango stone weevil numbers recorded in this research was attributed to the following factors: Intensive spraying of the orchards by farmers during the study period, low stone weevil populations, high concentrations of host plant volatiles released in the orchards, the possibility of the stone weevils to escape from the pyramid traps, and the fact that the essential oils used in this work was just a crude extract. 74    University of Ghana http://ugspace.ug.edu.gh   6.2. Recommendations This work should be continued in an unmanaged mango orchard in order to ascertain whether there will be an increase in the trap numbers of the mango stone weevils. As this study was done is a commercial orchards, results obtained may not be a reflection of the trap performance and hence conducting the study in an unmanaged orchard will help establish the actual performance of both the trap and lures. In future studies, it is recommended that trap inspection should be done regularly, at most every other day to avoid the situation where weevils will escape from the traps due to the fact that they stay in the trap for a long time to provide them the opportunity to leave the traps. Also addition of insecticide stripes could kill the insects before they escape from the traps. The essential oils need to be further analysed by GC-MS for their chemical constituents. The major constituents could be isolated and subsequently tested in an olfactometer for their suitability as lures. This could be followed up by production of the synthetic analogues of promising chemicals for further test in the field. The concentrations of the lures should be made higher than the concentrations released by host plant volatiles in subsequent research work so that the insects can detect the synthetic odor baits rather than the natural volatiles released by the plants. Researchers working on the mango stone weevil should study long-term trends in data sets including the phenology of the crop in order to make educated decisions about why the number of captures changed. Unusual changes in capture rates should trigger additional investigation to identify and address problem areas. 75    University of Ghana http://ugspace.ug.edu.gh   REFERENCES Abdallah, K. Z. (2012). Ghana National Mango Study. 57 pp. Accessed from; www.intracen.org National mango study Ghana.pdf on Accessed 21 August 2014 Abdullahi, G., Obeng-ofori, D., Afreh-Nuamah, K., and Billah M. K. (2011). 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Entomology Circular. 93:1-2 Woodruff, R. E., and Fasulo, T.R. (2006). The mango seed weevil, Sternochetus mangiferae (Fabricius) (Coleoptera: Curculionidae). Publication Number: EENY-371. Department of Entomology & Nematology, University of Florida, Institute of Food and Agricultural Sciences. http://creatures.ifas.uβ.edu/fruit/beetles/mango_seed_weevil.htm on Accessed 16 August 2014 87    University of Ghana http://ugspace.ug.edu.gh   APPENDICES Appendix 1. Standard least square analysis of variance showing the treatment effect and their interactions Source of variation DF Sum of squares F P<0.05 Location 2 0.30 3.89 0.0248 Trap type 1 0.21 5.55 0.0212 Lure type 3 0.37 3.21 0.0281 Trap type*lure type 3 0.41 3.60 0.0174 Location*trap type 2 0.11 1.49 0.2326 Location*lure type 6 0.22 0.98 0.4463 Location*trap type*lure type 6 0.33 1.45 0.2072 Appendix 2. One-way ANOVA for treatments used in the circle trap Source DF Sum of Mean Square F Ratio Prob > F Squares Lure type 3 0.2500000 0.083333 1.0000 0.4025 Rep 3 0.2500000 0.083333 1.0000 0.4025 Error 41 3.4166667 0.083333 C. Total 47 3.9166667 Appendix 3. One-way ANOVA for treatments in the pyramid trap Source DF Sum of Mean Square F Ratio Prob > F Squares Lure type 3 4.166667 1.38889 3.2233 0.0323* Rep 3 1.166667 0.38889 0.9025 0.4482 Error 41 17.666667 0.43089 C. Total 47 23.000000 88    University of Ghana http://ugspace.ug.edu.gh   Appendix 4. One-way ANOVA for trap treatments in Ayikuma Source DF Sum of Squares Mean Square F Ratio Prob > F Lure type 3 0.7500000 0.250000 1.3889 0.2693 Rep 3 0.2500000 0.083333 0.4630 0.7107 Error 25 4.5000000 0.180000 C. Total 31 5.5000000 Appendix 5 One-way ANOVA for trap treatments in Kpong Source DF Sum of Mean Square F Ratio Prob > F Squares Lure type 3 2.625000 0.875000 1.2238 0.3218 Rep 3 0.375000 0.125000 0.1748 0.9124 Error 25 17.875000 0.715000 C. Total 31 20.875000 Appendix 6 One-way ANOVA for trap treatments in Somanya Source DF Sum of Mean Square F Ratio Prob > F Squares Lure type 3 0 0 . . Rep 3 0 0 . . Error 25 0 0 C. Total 31 0 Appendix 7. T-test for the Two Trap Types in Ayikuma Source DF Sum of Mean Square T Ratio Prob > t Squares Trap type 1 0.5000000 0.500000 2.8421 0.1033 Rep 3 0.2500000 0.083333 0.4737 0.7032 Error 27 4.7500000 0.175926 C. Total 31 5.5000000 89    University of Ghana http://ugspace.ug.edu.gh   Appendix 8 .T-test for the Two Trap Types in Kpong Source DF Sum of Mean Square T Ratio Prob > t Squares Trap type 1 1.125000 1.12500 1.5677 0.2213 Rep 3 0.375000 0.12500 0.1742 0.9129 Error 27 19.375000 0.71759 C. Total 31 20.875000 Appendix 9. T-test for the Two Trap Types in Kpong Source DF Sum of Mean Square T Ratio Prob > t Squares Trap type 1 0 0 . . Rep 3 0 0 . . Error 27 0 0 C. Total 31 0 Appendix 10. One-way ANOVA for the Performance of the Circle Trap in the Three Study Areas Source DF Sum of Mean Square F Ratio Prob > F Squares Location 2 0.1666667 0.083333 1.0000 0.3765 Rep 3 0.2500000 0.083333 1.0000 0.4023 Error 42 3.5000000 0.083333 C. Total 47 3.9166667 Appendix 11. One-way ANOVA for the Performance of the Pyramid Trap in the Three Study Areas Source DF Sum of Mean Square F Ratio Prob > F Squares Location 2 2.000000 1.00000 2.1176 0.1330 Rep 3 1.166667 0.38889 0.8235 0.4883 Error 42 19.833333 0.47222 C. Total 47 23.000000 90    University of Ghana http://ugspace.ug.edu.gh   Appendix 12. ANOVA of release rate conducted in the mango orchard Source of Degrees of Sum of Mean F-value t-value variation freedom squares squares Lure 1 0.341 0.34 8.72 0.0419 Rep 4 0.360 0.090 2.30 0.2202 Error 4 0.157 0.040 C. Total 9 0.858 Appendix 13. ANOVA of release rate conducted in the laboratory Source of Degrees of Sum of Mean F-value t-value variation freedom squares squares Lure 1 0.26634240 0.266342 1.5316 0.2835 Rep 4 0.58314240 0.145786 0.8384 0.5658 Error 4 0.69557760 0.173894 C. Total 9 1.54506240   91