Cashew and Mango Integrated Pest Management Using Weaver Ants as a Key Element For organic cashew and mango growers in Africa Renkang Peng Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0909, Australia 1 ALL RIGHTS RESERVED This booklet has been produced by the author for cashew and mango technical and extension officers and organic farmers in Tanzania and Benin. The booklet may only be used in Tanzania and Benin. The text, 317 pictures and 30 figures and tables in this book have copyright. No parts of this booklet can be produced in any form or by any means, electronically, mechanically, by photocopying, recording or otherwise, without the prior permission of the author. Author’s email address: rkpeng1020 @hotmail.com or [email protected]. June 2015 2 Acknowledgements The project “Increasing value of African cashew and mango production” was financially supported by Danish Development Assistance Programs (DANIDA), Ministry of Foreign Affairs of Denmark. Charles Darwin University, Australia made generous contribution towards trip insurance and extra staff time for the author to conduct field work in Tanzania and Benin. I am grateful to Dr Mogens Gissel Nielsen, Dr Jørgen Aagaard Axelsen and Dr Joachim Offenberg for their support. I am also grateful to Professor Maulid Mwatawala, Dr Gration Rwegasira, Dr Sinzogan Antoine, Professor Vayssières Jean-François and Mr Halfan Nene for their help with booking air tickets and hotels, arranging vehicles for local travelling, and contributing their time to help with my field surveys and meetings with local experts. Ms Lanni Zhang and Dr Alan Andersen helped with the identification of the insect specimens collected in Tanzania and Benin. Ms Lanni Zhang provided her technical assistance for sorting samples, taking photos and measuring the size of the insect pests. Mr William George and Mr Nassor Rashid Abdallah provided me with summarised yield and net benefit data of cashew and mango from their long-term field experiments in Tanzania. Mr Nassor Rashid Abdallah provided me with summarised data of the effect of weaver ants on mango fruitflies. Ms Florence Anato and Ms Rosine Wargui provided me with the cashew and mango yield data from their long-term field experiments in Benin. I thank Mr William George, Mr Nassor Rashid Abdallah, Mr Halfan Nene, Ms Florence Anato, Ms Rosine Wargui and Mr Ouagoussounon Issa for the provision of local information, organization of meetings with local agricultural authorities, farmers’ associations and farmers and their time to help with my field surveys. I also thank Mr Halfan Nene, Ms Rosalia Shayo, and Mr Ouagoussounon Issa for their time to discuss the biology of African weaver ants. Mr Agboton Cyriaque provided basic information about the lifecycle and the damage of the cashew trunk borer and allowed me to take photos of the trunk borer specimens he collected. Mr Uda at Masasi High Quality Farmers Products, Masasi provided his good service for me to visit organic cashew smallholders. Mr Mussa, Mr Lupembe, Mr Magere Emmanuel, Mr Sakina Amuli, Mr May Yusefe, Mr Sungura, Mr Said Lwambo, Mr Simon and Naliendele Agricultural Institute allowed me to conduct field surveys in their orchards. All the researchers of the project “Increasing value of African cashew and mango production” who participated in the final workshop of the project provided positive comments on the photo book. Dr Jørgen Aagaard Axelsen and Professor Vayssières Jean- François made specific and useful comments and suggestions. 3 Introduction Background Cashew (Anacardium occidentale L.) and mango (Mangifera indica L.) are high-value economic commodities in east and western Africa. These crops are an important source of livelihood, food security and income for over 8 million smallholder farmers (Maniania, 2011; Topper and Kasuga, 2003). Cashew is a drought tolerant tree with an ability to grow in poor soils. It is an attractive commercial crop grown by many smallholders and contributes 50- 90% of their total farm income, and it is one of the major sources of foreign exchange with exports worth over USD400 million annually for east and western Africa (Maniania, 2011). However, the cashew production is currently affected by many constraints, especially biological. The damage by the powdery mildew disease, sap-sucking bugs and thrips can lead to 60-100% yield losses in east Africa (Agboton et al., 2013). In western Africa, sap-sucking bugs, fruit-nut thrips and stem borers severely hamper production and greatly reduce the income of cashew smallholders. Mango trees are widely cultivated in east and western Africa as well and contribute to farmer family diets as well as serving as a cash crop. However, there are a number of production- related constraints at farm level, especially insect pest and disease problems which can result in total yield loss (Annon, 2014; Kilcher and Ssebunya, 2011). Major pests are fruit flies, the seed weevil, thrips, scales and mealybugs. Anthracnose and powdery mildew diseases are common in almost all mango growing areas. Because of these pest problems, some cashew and mango smallholders manage their orchards poorly, and even totally neglect them, but they become interested only during the harvest time. As a result, annual income from cashew and mango trees is very limited. For the others, to minimize the pest damage, they rely on pesticides for a better harvest. However, the net income is still limited because of (1) high costs of pesticides and the related expenses, and (2) low efficiency of sprays due to the lack of monitoring program by themselves. Instead, the frequent use of pesticides results in pest resistance, the reduction of natural enemies, pollinators, environmental pollution, and a threat to farmers’ health and their animals (Christian et al., 2013; Hill, 2008; Hill and Waller, 1988). Therefore, cost-effective and environmentally sound integrated pest (IPM) management programs for mango and cashew crops have to be explored. Weaver ants, Oecophylla longinoda, have been documented as effective biocontrol agents of a range of cashew and mango insect pests in Africa (Anato et al, 2015; Diamé et al, 2015 ; Vayssières et al, 2015a; Materu et al., 2014; Ativor et al., 2012; Olotu et al., 2012; Dwomoh et al., 2009; Van Mele et al., 2009; Peng, 2002; Stathers, 1995), and this ant is widely distributed in cashew and mango orchards if no regular pesticides are used. A sister species of weaver ants, Oecophylla smaragdina, in Asia has been successfully used as a key component in several organic and conventional IPM programs to manage the main insect pests and even a few diseases on cashew, mango and African mahogany in Australia (Peng and Christian, 2005a, b; Peng et al. 2009, 2004;), on cashew and citrus crops in Vietnam (Peng et al., 2008a, b; Van Mele 2008), on cashew crops in Papua New Guinea (Peng 2001, 2000; Peng and Duncan, 1999) and East Timor (Peng et al., 2015; Amaral, 2010). Given the similarity of forage and territorial behaviour between weaver ants, O. longinoda, in Africa and weaver ants, O. smaragdina, in Asia, African weaver ants should have high potential to be used to control the main pests of cashew and mango crops in Africa. A research project “Increasing 4 value of African cashew and mango production” was conducted from 2010-2015 using African weaver ants and organic fungicides as major components to develop IPM programs for organic cashew and mango smallholders in Tanzania and Benin. Development of cashew and mango IPM programs From 2010 to 2015, project researchers conducted: (1) Four long-term field experiments in cashew and mango orchards in Tanzania and Benin using African weaver ants and organic pesticides as major components, (2) 27 field surveys in different types of cashew and mango orchards with weaver ants in Tanzania and Benin, (3) 12 interviews of local cashew and mango experts, and (4) 30 interviews of cashew and mango smallholders and farmers’ associations. The main results showed that: (1) IPM treatments achieved significantly higher yield and higher net income than pesticide treatments or controls, (2) Trees with weaver ants were much better protected from the main insect pest damage and the shoot dieback disease compared to trees without the ants, (3) Most local cashew and mango experts and smallholders believed that weaver ants would play an important role in limiting insect pest damage, and (4) The main pest complex in Tanzania is generally similar to that in Benin, but the degree of the pest damage is different. For example, powdery mildew disease is very serious annually in Tanzania, but not in Benin. Based on these results, together with available information in the literature, two preliminary IPM programs for organic cashew and mango growers have been developed using local weaver ants, organically approved pesticides and advanced farming skills below. Cashew IPM program for Tanzania and Benin organic smallholders. IPM Period of tree dormancy Period of flowering Period of harvest and component and/or leaf flush (wet and fruiting post-harvest season) (dry season) (later dry season) Bio-control Manage weaver ant Manage weaver ant Manage weaver ant agents colonies on trees colonies on trees colonies on trees Organically Spray fungicides to approved control powdery mildew pesticides disease if needed Spray Spinosad or neem oil to control fruit-nut thrips if needed Farming Prune trees Maintain firebreaks Clean tree base to strategies promote harvest Intercrop and/or weed Irrigate trees if water is Collect nuts as available frequently as possible Make and use organic Intercrop if needed Dry nuts in the sun fertilizer Mulch trees Store nuts in a dry and ventilated room Plant new trees if needed Maintain firebreaks 5 Mango IPM program for organic smallholders in Tanzania and Benin. IPM Period of tree dormancy Period of flowering Period of harvest and components and/or leaf flush (wet and fruiting (dry post-harvest season) season) (later dry season) Bio-control Manage weaver ant Manage weaver ant Manage weaver ant agents colonies on trees colonies on trees colonies on trees Organically Spray fungicides to Spot-spray fruitfly bait approved control anthracnose or (Spinosad) once a pesticides and powdery mildew week until finishing micronutrients disease if needed harvest Spray micronutrients if applicable Spot-spray white oil (2%) when >10% fruits /tree have scales and/or mealybugs Farming Prune trees Maintain firebreaks Pick fruits when they strategies are green mature Intercrop and/or weed Tape tree trunk and Immerse fruits in hot smear with sticky water (53oC) for 5 materials to control minutes to control seed weevil if needed fruitflies and anthracnose Make and use organic Irrigate trees if water Pick and destroy all fertilizer is available the fallen fruits Mulch trees Pick and destroy all the fallen fruits Plant new trees if needed Intercrop if needed Maintain firebreaks These IPM programs are explained and described step-by-step in this photo book. Guidance of the photo book The photo book focuses on maintaining the ecological balances between pests and their natural enemies, emphasizing the role of local weaver ants in the cashew and mango orchards and introducing the methods of organic cashew and mango production and sustainability using weaver ants as a key element. The developed IPM programs (see above) are based on tree phenology because of close relationship between the tree phenology, pest occurrence and farming activities. Therefore, this book applies to both Benin and Tanzania. When the climate has no big changes between years, the tree phenology is closely related to calendar months, which are geographically different between Tanzania and Benin. For those farmers who get used to calendar months as indicators for their farming activities to manage cashew and/or mango crops, a conversion table of tree phenology to calendar months for Tanzania and Benin is shown below. Most farming strategies are similar for both cashew and mango crops, but a few are different, for example, pruning and pest management. Therefore, if a farming activity can be applied to both crops, the sub-title of each farming activity will be followed by bracketing cashew and 6 mango. If a farming activity is different between the two crops, under the sub-title of the activity, each crop is described separately. General conversion of tree phenology to calendar month Crop Phenology Location Calendar month Cashew Tree dormancy and/or leaf Tanzania January - June flush Benin April - September Tree flowering and nut setting Tanzania July - September Benin December - February Harvest and post-harvest Tanzania October - December Benin January - March Mango* Tree dormancy and/or leaf Tanzania February - July flush Benin July - November Tree flowering and fruit Tanzania July - October setting Benin December - March Harvest and post-harvest Tanzania November - February Benin April - June *, Mango has many varieties, and each variety may have slight different phenology period. This photo book consists of 9 parts:  Part 1 “Cashew and mango orchard management” contains 25 pictures, 5 figures and 2 tables, showing the importance and management skills of five major farming activities, demonstrating the results of IPM treatment against insecticide treatment and control, and summarising the developed cashew and mango IPM programs.  Part 2 “Cashew insect pests, their natural enemies and the control strategies” contains 123 pictures, 5 figures and 1 table, showing the morphology of the main cashew insect pests, their damage symptoms, the control efficiency by weaver ants, recommended control strategies and the use or protection of other natural enemies found in cashew orchards.  Part 3 “Cashew diseases and their management” has 21 pictures, 2 figures and 1 table, showing the symptoms of the main cashew diseases and the recommended control methods.  Part 4 “Mango insect pests, their natural enemies and the control strategies” contains 61 pictures, 6 figures and 1 table, showing the morphology of the main mango insect pests, the damage symptoms, the control efficiency by weaver ants, the recommended control strategies and the use or protection of other natural enemies found in mango orchards.  Part 5 “Mango diseases and their management” has 11 pictures and 1 table, showing the symptoms of the most important or common mango diseases and the control methods.  Part 6 “Why weaver ants protect cashew and mango trees” contains 20 pictures, demonstrating the relationship among the foraging behaviour of the ants, extrafloral nectar secreted by cashew and mango trees, ant pheromone and insect pests.  Part 7 “Basic biology of weaver ants” contains 24 pictures, showing the life cycles of African weaver ants and their main behaviour.  Part 8 “How to use weaver ants in cashew and mango orchards” contains 29 pictures and 6 figures, describing how to install weaver ant colonies in cashew and mango orchards step-by-step, how to determine their abundance at the colony level and how to maintain the ant colonies. 7  Part 9 is a checklist of the IPM programs, reminding cashew and mango farmers when to do what. All the pictures contained in this book were taken by Dr Renkang Peng except for those whose authorships are mentioned under the pictures. Who can use this photobook This book is written for cashew and mango technical and extension officers and for organic cashew and mango farmers who will participate in farmer field school training and for their future reference. It is also a useful book for cashew and mango IPM trainers. Because of the geographical proximity, those parts which are applicable to Tanzania farmers may also be applicable to farmers in Mozambique, Kenya and Angola. Those parts which are applicable to farmers in Benin may also be applicable to farmers in Togo, Nigeria, Ghana, Burkina Faso and Cote D’ivoire. Given the similarity of pests among tropical tree crops, and the effectiveness of weaver ants against a wide range of pests (caterpillars, sap-sucking bugs, beetles and fruitflies), this photo book can be a useful reference for researchers, university students, agricultural school teachers and students, and extension officers who work with tropical tree crops, such as avocado, citrus, coconut, cocoa and agroforest trees. Because this photo book contains details of the bio-ecology and management of weaver ant colonies, it is also a useful book for people who study weaver ants. 8 Contents Acknowledgements .. .. .. .. .. .. .. .. .. 3 Introduction (including organic cashew and mango IPM programs) .. .. .. 4 Part 1 Cashew and mango orchard management .. .. .. .. .. 12 1.1 Bushfire control (for cashew and mango) .. .. .. .. 12 1.1.1 Impact of bushfire .. .. .. .. .. .. 12 1.1.2 How to control bushfire .. .. .. .. .. 13 1.2 Weeding, mulching and intercropping (for cashew and mango) .. 13 1.2.1 Young orchards (weeding and mulching) .. .. .. 13 1.2.2 Young orchards (intercropping) .. .. .. .. 14 1.2.3 Mature orchards .. .. .. .. .. .. 15 1.3 Farm-made organic fertilizer and its use (for cashew and mango) .. 15 1.3.1 Use of organic fertilizer .. .. .. .. .. 15 1.3.2 How to make organic fertilizer .. .. .. .. 16 1.4 Pruning .. .. .. .. .. .. .. .. 17 1.4.1 Cashew tree pruning .. .. .. .. .. .. 17 Pruning tools .. .. .. .. .. .. 17 Pruning time .. .. .. .. .. .. 18 Young trees .. .. .. .. .. .. 18 Production trees .. .. .. .. .. 20 1.4.2 Mango tree pruning .. .. .. .. .. .. 20 Pruning time .. .. .. .. .. .. 20 Young trees .. .. .. .. .. .. 20 Production trees .. .. .. .. .. 21 1.5. Irrigation (for cashew and mango) .. .. .. .. .. 21 1.5.1 Young trees .. .. .. .. .. .. .. 21 1.5.2 Production trees .. .. .. .. .. .. 22 1.6 Integrated pest management (IPM) .. .. .. .. .. 22 1.6.1 Cashew .. .. .. .. .. .. .. 22 Experiment in Tanzania .. .. .. .. 23 Experiment in Benin .. .. .. .. .. 24 Field surveys in Tanzania and Benin .. .. .. 24 Conclusion and the development of cashew IPM program 24 1.6.2 Mango experiments .. .. .. .. .. .. 25 Experiment in Tanzania .. .. .. .. 25 Experiment in Benin .. .. .. .. .. 27 Field surveys in Tanzania and Benin .. .. .. 27 Conclusion and the development of mango IPM program 27 Part 2 Cashew insect pests, their natural enemies and the control strategies .. 29 2.1 Insect pests that can be controlled by weaver ants .. .. .. 30 2.1.1 Coconut bugs .. .. .. .. .. .. .. 30 2.1.2. Mosquito bugs .. .. .. .. .. .. .. 32 2.1.3. The red-banded thrips .. .. .. .. .. .. 34 2.1.4. Other pest bugs .. .. .. .. .. .. 35 2.2 Insect pests that are associated with weaver ants .. .. .. 37 2.2.1 Aphids .. .. .. .. .. .. .. .. 37 2.2.2 Mealy bugs .. .. .. .. .. .. .. 39 9 2.2.3 Brown scales .. .. .. .. .. .. .. 40 2.3 Insect pests that cannot be fully controlled by weaver ants .. .. 41 2.3.1 Fruit-nut thrips .. .. .. .. .. .. 41 2.3.2 The trunk borer (Mecocorynus loripes) .. .. .. 43 2.3.3 The trunk borer (Apate telebrans) .. .. .. .. 45 2.4 Other common beneficial organisms in cashew orchards .. .. 47 2.4.1 Spiders .. .. .. .. .. .. .. 47 2.4.2 Preying mantids .. .. .. .. .. .. 48 2.4.3 Ladybird beetles .. .. .. .. .. .. 48 2.4.4 Lacewing .. .. .. .. .. .. .. 49 2.4.5 Hoverfly .. .. .. .. .. .. .. 49 2.4.6 Preying bugs .. .. .. .. .. .. .. 50 2.4.7 Other predators .. .. .. .. .. .. 50 2.4.8 Parasitic wasps .. .. .. .. .. .. 50 2.4.9 Beneficial micro-organisms .. .. .. .. .. 51 2.4.10 Other beneficial insects .. .. .. .. .. 51 Part 3 Cashew diseases and their management .. .. .. .. .. 52 3.1 Powdery mildew disease .. .. .. .. .. .. 52 3.2 Shoot dieback .. .. .. .. .. .. .. .. 54 3.3 Cashew leaf and nut blight .. .. .. .. .. .. 55 3.4 Anthracnose .. .. .. .. .. .. .. .. 57 Part 4 Mango insect pests, their natural enemies and the control strategies .. .. 58 4.1 Insect pests that can be controlled by weaver ants .. .. .. 59 4.1.1 The red-banded thrips .. .. .. .. .. .. 59 4.1.2 Coconut bugs .. .. .. .. .. .. .. 60 4.1.3 Mosquito bugs .. .. .. .. .. .. .. 62 4.1.4 The leaf beetle .. .. .. .. .. .. .. 63 4.2 Insect pests that cannot be fully controlled by weaver ants .. .. 64 4.2.1 Fruit flies .. .. .. .. .. .. .. 64 4.2.2 The mango seed weevil .. .. .. .. .. 66 4.2.3 Fruit thrips .. .. .. .. .. .. .. 68 4.3 Insect pests that are associated with weaver ants .. .. .. 69 4.3.1 The flat scale .. .. .. .. .. .. .. 69 4.4 Other common beneficial organisms found in mango orchards .. 70 4.4.1 Spiders .. .. .. .. .. .. .. 70 4.4.2 Preying mantids and mantispids .. .. .. .. 71 4.4.3 Ladybirds .. .. .. .. .. .. .. 72 4.4.4 Other beneficial organisms .. .. .. .. .. 72 Part 5 Mango diseases and their management .. .. .. .. .. 73 5.1 Powdery mildew disease .. .. .. .. .. .. 73 5.2 Anthracnose .. .. .. .. .. .. .. .. 74 5.3 leaf algal spot .. .. .. .. .. .. .. .. 75 Part 6 Why weaver ants protect cashew and mango trees .. .. .. .. 76 6.1 Sugar solution .. .. .. .. .. .. .. .. 76 6.2 Meat .. .. .. .. .. .. .. .. .. 77 6.3 Ant pheromone .. .. .. .. .. .. .. 77 10