WEAVER ANT OECOPHYLLA LONGINODA LATREILLE (HYMENOPTERA FORMICIDAE) AS BIOCONTROL AGENT ON MAJOR INSECT PESTS OF CASHEW AND MANGO IN TANZANIA NASSOR RASHID ABDULLA A THESIS SUBMITTED IN FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY OF SOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA. 2016 ii EXTENDED ABSTRACT Experiments to determine the potential of Weaver ants, Oecophylla longinoda Latreille (Hymenoptera: Formicidae) as biocontrol agents of major insect pests of cashew and mango were conducted at Naliendele Agricultural Research Institute in Mtwara and Kibaha in the Coast region, during 2012/13 and 2013/14 fruiting seasons. Cashew is attacked by Coconut bugs, Pseudotheraptus wayi Brown; Mirid bugs, Helopeltis spp. and Thrips, Selenothrips rubrocinctus Giard. Mango is threatened by several fruit fly species and the mango seed weevils, Sternochetus mangiferae (Fabricius); both being quarantine pests. Farmers use synthetic insecticides to control these pests and no alternative measures are available for organic growers. Reliance on chemical control measures has not made it possible to suppress the pests‟ populations to uneconomic levels. Similarly, dependency on insecticides for the control of S. mangiferae during flowering season has not proven very successful. In the current study, the efficiency of O. longinoda as bio-control agents was compared with Karate® (lambda-cyhalothrin) and the control plots against Cashew insect pests. On mango, the efficacy of O. longinoda was compared with Dudumida (70WDG Imidacloprid) and the control against fruit flies and the S. mangiferae. The results indicated significantly lower (P<0.0001) damages for the three cashew pests in the protected trees compared to control. For two seasons, P. wayi damage was <5% in protected trees as opposed to 29% and 25% in the unprotected plots; Helopeltis spp damage was <3% in protected trees for two seasons as opposed to >8% and >6% in unprotected, and S. rubrocinctus damage was <11% in iii protected trees for both seasons as opposed to >41% and >39% in the unprotected plots in 2012/13 and 2013/14 respectively. Incidences of fruit flies was <6% and <8% in protected trees as opposed to >18% and >24% in the unprotected in 2012/13 and 2013/14 respectively, whereas incidences of S. mangiferae was <7% and <8% in protected trees as opposed to >24% and >30% in unprotected trees in 2012/13 and 2013/14 respectively. Throughout the experiments O. longinoda was as effective as insecticides in controlling major cashew and mango insect pests. Thus, O. longinoda can serve as a substitute to insecticides. iv DECLARATION I, NASSOR RASHID ABDULLA do hereby declare to the Senate of Sokoine University of Agriculture that this thesis is my own original work done within the period of registration and that it has neither been submitted nor being concurrently submitted in any other institution. _________________________________ _____________________ Nassor R. Abdulla Date (PhD Candidate) The above declaration is confirmed _________________________________ _____________________ Dr. G. M. Rwegasira Date (Supervisor) _________________________________ _____________________ Dr. Karl-Martin Vagn Jensen Date (Supervisor) v COPYRIGHT No part of this thesis should be reproduced, stored in any retrieval system, or transmitted in any form or by any means without a prior written permission of the author or Sokoine University of Agriculture in that behalf. vi ACKNOWLEDGEMENTS First and foremost I would like to thank the Almighty ALLAH (Subha‟anahu Wata'ala) who kept me healthy and strong from the commencement to the successful completion of this great task. I am highly indebted to my supervisor Dr. Gration M. Rwegasira, Department of Crop Science and Horticulture, Sokoine University of Agriculture (SUA) Morogoro, Tanzania and co-supervisor Dr. Karl-Martin Vagn Jensen, Department of Agroecology Aarhus University, Slagelse, Denmark for their dedicated supervision, technical advices, constructive criticism and guidance extended to me during early stages of research proposal development, entire field work and writing of the manuscripts. I am grateful to Prof. Maulid W. Mwatawala, Department of Crop Science and Horticulture, (SUA) Morogoro, Tanzania and Dr. Joachim Offenberg, of the Department of Bioscience, Aarhus University, Denmark who moulded me with their experienced scientific advices that resulted into the shaping of this work. Special appreciations and thanks are extended to the Director of Naliendele Agricultural Research Institute (NARI), Mtwara, Tanzania for granting a permission to conduct research in their cashew orchards and provision of technical assistance whenever needed. Support from Messrs; Hassan Libubulu, Hamza Mawazo, Mohammed Machunja and Mohammed Salim during the field activities on cashew is acknowledged as well. vii I would also like to thank Mr. Lupembe, owner of the mango orchard at Kibaha for granting a permission to conduct the experiments in his farm. Furthermore I would like to thank Mr. Nsami, E. of the National Biological Control Unit (NBCU), Kibaha Tanzania for provision of space in the laboratory during fruit culturing experiments. Ms. Jesca Isaya and Mr. Saadani Mohammed of NBCU, Kibaha Tanzania are highly appreciated for their excellent assistance during the entire period of field and laboratory works on mango. The advice and encouragement from all members of the Department of Crop Science and Horticulture at SUA and my colleagues at the working station with whom I interacted throughout the course of this study are hereby acknowledged. Equally important are my fellow Postgraduate students in particular, Rozalia G. Rwegasira, William J. George; Wilson A. Nene; Ali Khatib Bakar and Mary A. Ndimbo. The encouragement and moral support from my spouse Asha, our beloved children and all family members for their never ending support, patience and stability during my long absence from home particularly at time of extreme difficulties will always be remembered. Lastly, but definitely not least my profound gratitude goes to the Danish International Development Assistance (DANIDA) for making my dream come true by sponsoring my PhD studies at SUA. The Ministry of Agriculture and Natural Resources (MANR), Zanzibar is acknowledged for granting me a study leave. viii DEDICATION This work is dedicated to my revered late parents Father, Sheikh Rashid Abdulla Nassor and Mother, Sheikha Nassor Mohammed, the fountain of inspiration in my academic achievements but sadly, they both passed away in 1969 and 2008 respectively. Oh Allah! Please rest their souls in holy spirits – A‟amiyn. ix TABLE OF CONTENTS EXTENDED ABSTRACT .......................................................................................... ii DECLARATION ....................................................................................................... iv COPYRIGHT.............................................................................................................. v ACKNOWLEDGEMENTS ....................................................................................... vi DEDICATION ......................................................................................................... viii TABLE OF CONTENTS ........................................................................................... ix LIST OF TABLES .................................................................................................. xvii LIST OF FIGURES ................................................................................................. xix LIST OF PLATES .................................................................................................. xxii LIST OF PUBLICATIONS (PEER REVIEWED JOURNAL PAPERS) (ABSTRACTS) .................................................................................... xxiii LIST OF ABBREVIATIONS AND SYMBOLS ................................................... xxiv CHAPTER ONE ......................................................................................................... 1 1.0 General Introduction and Literature Review ............................................................ 1 1.1 Cashew Taxonomy, Origin and Distribution ............................................................ 1 1.2 Description of the Cashew Plant .............................................................................. 2 1.3 Climatic and Soil Requirements .............................................................................. 3 1.4 Importance of Cashew Crop .................................................................................... 4 1.5 Contribution of Cashew in Cash Income Earnings ................................................... 5 1.6 Constraints in Cashew Production ........................................................................... 6 x 1.7 Cashew Insect Pests ................................................................................................ 6 1.7.1 The coconut bugs ............................................................................................... 7 1.7.1.1 Biology of P. wayi....................................................................................... 8 1.7.2 Tea mosquito bugs ............................................................................................. 9 1.7.2.1 Biology of Helopeltis anacardii ............................................................ 10 1.7.2.2 Biology of Helopeltis schoutedeni......................................................... 11 1.7.3