the challenge and prospects of dispute settlement mechanisms in addis ababa civil service agency

149 Pages·2017·3.93 MB·English

Addis Ababa University
Graduate Programme

College of Natural and Computational Sciences
Department of Zoological Sciences (Insect Sciences Stream)

The role of grasses in natural breeding habitats of gravid female Anopheles
mosquitoes (Diptera: Culicidae) on oviposition preference as well as larval
development and survival
By
Yelfwagash Asmare
A dissertation submitted to the Graduate Programme of Addis Ababa University in partial
fulfilment of the requirement for the degree of Doctor of Philosophy in Biology (Insect Sciences)

August/ 2017
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Dedication
The thesis is dedicated to my beloved father Asmare Kessete (Baba) and mother Birhane
Demeke (Tata) for their prayers, innumerable love and encouragement.

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Acknowledgement
First and foremost, I thank Almighty God for His help to undertake this research and for His
infinite blessings throughout my life.
I would like to express sincere gratitude to my supervisor, Dr. Habte Tekie, Associate Professor
at the Department of Zoological Sciences, Addis Ababa University (AAU), for accepting me as a
PhD student and his patience, guidance, encouragement and invaluable advice throughout my
time as his student. I am also sincerely thankful to the late Dr. Emiru Seyoum, Associate
professor, AAU; may God place his soul in heaven.
I am deeply grateful to Prof. Rickard Ignell, Head of Division of Chemical Ecology, Department
of Plant Protection Biology, Swedish University of Agricultural Sciences (SLU), Alnarp,
Sweden, for his invaluable support and advice throughout this study as well as in writing the
manuscripts to be achieved for publication. In addition, I would like to express my heartfelt
thanks to Dr. Sharon Hill, Associate professor at Division of Chemical Ecology, Department of
Plant Protection Biology, SLU, Alnarp, Sweden. I am grateful for her support, invaluable
comments, and statistical advice. Moreover, I would like to thank Dr. Richard Hopkins, Head of
Pest Behaviour, Natural Resources Institute, Faculty of Engineering and Science, University of
Greenwich, U.K. for his constructive ideas in my studies. I sincerely thank all members of the
chemical ecology group at Alnarp, SLU for their supports with great scientific environment.
In addition, I like to gratefully express my sincere thanks to Prof. Abebe Getahun, Chairman,
Department of Zoological Sciences (AAU) for his encouragement and patience to accept my
justification for the extension of study period at AAU. I would also like to express my sincere
thanks to all staff members and students of the Insect Science stream at the Department of
Zoology (AAU) for their support and assistance.
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I would like to acknowledge the Swedish Institute Guest Scholarship Program for providing me
the scholarship and their financial support which helped me to pursue my work at SLU, Alnarp,
Sweden. Without their invaluable support, it would have been impossible to conduct this
research.
I would like to express my heartfelt thanks to Debre Markos University (DMU), my employer
and sponsor, for granting me the study leave and financial support for my study. I sincerely
thank and acknowledge the School of Chemical and Food Engineering, Bahir Dar University
(BDU), for their support with laboratory facilities in plant oil extraction for mosquito larval
bioassays. I would like to extend my thanks to the Ethiopian Public Health Institute (EPHI) for
their generous support in mosquito rearing and laboratory bioassays. I would like to express my
appreciation to all staff members at these institutions; special thanks to Dr. Adugna Weyessa at
EPHI for his cooperation to provide the latest revised mosquito rearing manual. I am also
sincerely thankful for the people in the villages around Lake Tana and Mecha Wereda
Agriculture and Rural Development Office in Merawi town for their kind assistance and support
during my field visits for sample collection.
I am very grateful to my parents (Asmare and Birhane), brothers (Kassahun, Yohanes and
Yacobe), and sisters (Tazash, Shega, and Mintwab) for their love, encouragement and prayers.
My family deserves a lot of credit and appreciation. I am extremely grateful to my beloved
husband Esubalew Mengistie for his love, understanding, prayers, consistent encouragement and
patience to complete my study. I am also thankful to my children (Selamawit, Hanna, and
Paulos) for their love that makes me happy and strong.

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Abbreviations and Acronyms
ACT Artemisinin-Based Combination Therapy

BH-660 Bako Hybrid-660

Bti Bacillus thuringiensis israelensis

Bs Bacillus sphaericus

DEET N, N-Diethyl-meta-toluamide

DDT Dichlorodiphenyltrichloroethane

IRS Indoor Residual Spraying

ITNs Insecticide Treated Nets
IVM Integrated Vector Management

IMVM Integrated Malaria Vector Management

LLINs Long-Lasting Insecticidal Nets

PMD p-menthane-3, 8-diol

SIT Sterile Insect Technique

WHO World Health Organization

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Table of Contents
Dedication-----------------------------------------------------------------------------------------------------iii
Acknowledgements------------------------------------------------------------------------------------------iv
Abbreviations and Acronyms-------------------------------------------------------------------------------vi
Table of Contents--------------------------------------------------------------------------------------------vii
List of Figures------------------------------------------------------------------------------------------------xii
List of Tables-------------------------------------------------------------------------------------------------xv
Abstract-------------------------------------------------------------------------------------------------------xvi
Chapter 1. General Introduction .............................................................................................. 1
1.1. Malaria transmission trends and interventions .................................................................. 1
1.1.1. Global malaria disease burden ................................................................................1
1.1.2. Malaria situation in Ethiopia ..................................................................................1
1.1.3. Malaria parasites ....................................................................................................2
1.1.4. Anopheles mosquitoes and malaria .........................................................................3
1.1.5. Factors regulating malaria transmission..................................................................4
1.1.6. Emerging approaches in malaria vector management .............................................5
1.2. Rationale of the study ........................................................................................................... 7
1.3. Objectives of the study ......................................................................................................... 8
1.3.1. General objective........................................................................................................8
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1.3.2. Specific objectives ......................................................................................................8
Chapter 2. Literature Review ................................................................................................... 9
2.1. Malaria parasite biology and transmission pattern ................................................................ 9
2.2. Biology and life cycle of Anopheles mosquitoes ................................................................. 12
2.3. Distribution of major malaria vectors in Africa ................................................................... 14
2.4. Ecology and behavior of Anopheles mosquitoes ................................................................. 16
2.4.1. Sugar feeding in Anopheles mosquitoes .................................................................... 17
2.4.2. Mating, host-seeking, and blood feeding in Anopheles mosquitoes ........................... 17
2.4.3. Oviposition site selection by gravid Anopheles mosquitoes ....................................... 19
2.5. Factors regulating Anopheles mosquito populations ............................................................ 21
2.5.1. Environmental factors .............................................................................................. 21
2.5.2. Biotic resources in Anopheles breeding habitats ........................................................ 22
2.5.3. Biotic mortality factors in Anopheles mosquitoes ..................................................... 23
2.6. Vector management in malaria control ............................................................................... 24
2.6.1. Chemical insecticide-based vector management ....................................................... 25
2.6.2. Non-chemical vector management options................................................................ 26
2.6.3. Genetic modification in mosquito vector management .............................................. 28
2.7. Challenges and perspectives in malaria vector management ............................................... 29
Chapter 3. The Role of Grass Volatiles on Oviposition Preferences by Anopheles arabiensis
and Anophele coluzzii .............................................................................................................. 32
3.1. Introduction ........................................................................................................................ 32
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3.2. Materials and methods ........................................................................................................ 34
3.2.1. Description of study sites and Anopheles larval sampling ......................................... 34
3.2.2. Headspace odour collection from grasses in breeding habitats .................................. 35
3.2.3. Anopheles mosquito rearing ...................................................................................... 36
3.2.4. Wind tunnel attraction bioassay ................................................................................ 37
3.2.5. Two-choice oviposition bioassay in experimental cages ........................................... 38
3.2.6. Multi-choice oviposition bioassay in semi-field tent experimental setting ................. 39
3.2.7. Statistical analyses .................................................................................................... 41
3.3. Results ............................................................................................................................... 41
3.3.1. Anopheles arabiensis larval density in natural grass habitats ..................................... 41
3.3.2. Attraction of Anopheles arabiensis and Anopheles coluzzii to grass volatiles ............ 43
3.3.3. Oviposition response of Anopheles arabiensis and Anopheles coluzzii to grass
volatiles ............................................................................................................................. 45
3.3.4. Tent experiments response of gravid Anopheles arabiensis and Anopheles coluzzii to
grass volatiles .................................................................................................................... 47
3.4. Discussion .......................................................................................................................... 49
3.5. Conclusions ........................................................................................................................ 51
Chapter 4. Grass Pollen Affects Survival and Development of Larval Anopheles arabiensis
Patton ...................................................................................................................................... 52
4.1. Introduction ........................................................................................................................ 52
4.2. Materials and Methods ....................................................................................................... 54
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4.2.1. Pollen collection ....................................................................................................... 54
4.2.2. Pollen nutrient analysis ............................................................................................. 55
4.2.3. Pollen grain size analysis .......................................................................................... 56
4.2.4. Mosquito rearing ...................................................................................................... 56
4.2.5. Larval development and survival analyses ................................................................ 57
4.2.6. Data analyses............................................................................................................ 58
4.3. Results ............................................................................................................................... 59
4.3.1. Pollen grain size and nutrient content ....................................................................... 59
4.3.2. Anopheles larval survival .......................................................................................... 60
4.3.3. Effect of pollen on pupation of Anopheles arabiensis ............................................... 63
4.3.4. Effect of grass pollen in the larval diet on adult emergence ....................................... 65
4.4. Discussion .......................................................................................................................... 66
4.5. Conclusions ........................................................................................................................ 69
Chapter 5. Effects of Oil Extracts from Typha latifolia and Cyperus papyrus on Survival of
An. arabiensis Larvae .............................................................................................................. 71
5.1. Introduction ........................................................................................................................ 71
5.2. Materials and Methods ....................................................................................................... 73
5.2.1. Test plant oil extraction procedures .......................................................................... 73
5.2.2. Experimental mosquito rearing procedures ............................................................... 75
5.2.3. Bioassays on Anopheles arabiensis larval survival with grass oils ............................ 76
5.2.4. Statistical analyses .................................................................................................... 77
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