bahir dar university college of agriculture
TRANSCRIPT
BAHIR DAR UNIVERSITY
COLLEGE OF AGRICULTURE AND ENVIRONMENTAL SCIENCES
POSTGRADUATE PROGRAM
ASSESSMENT AND MANAGEMENT OF WHITE MANGO SCALE (Aulacaspise tubercularis Newstead) ON MANGO (Mangifera indica L.) IN
BAHIRDAR ZURIA DISTRICT, NORTH WESTERN ETHIOPIA
MSc Thesis
By
ALEBEL ESKEZIA ADAM
April, 2022
Bahir Dar, Ethiopia
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BAHIR DAR UNIVERSITY
COLLEGE OF AGRICULTURE AND ENVIRONMENTAL SCIENCES
POSTGRADUATE PROGRAM
ASSESSMENT AND MANAGEMENT OF WHITE MANGO SCALE
(Aulacaspise tubercularis Newstead) ON MANGO (Mangifera indica L.) IN
BAHIRDAR ZURIA DISTRICT, NORTH WESTERN ETHIOPIA MSc Thesis
By
ALEBEL ESKEZIA ADAM
A THESIS SUBMITTED TO THE COLLEGE OF AGRICULTURE AND ENVIRONMENTAL SCIENCES
GRADUATE PROGRAM OF BAHIR DAR UNIVERSITY IN PARTIAL FULFILMENT OF THE
REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE (M.Sc.) IN PLANT PROTECTION
Department: Plant science
Program: M.Sc. plant protection
My adviser: Abaynew Jemal (PhD)
April, 2022
Bahir Dar, Ethiopia
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ACKNOWLEDGEMENTS
First of all, I would like to say thank you for sincere gratitude and appreciation to my major
advisor Dr. Abaynew Jemal for supporting me from the beginning up to the final work of
the thesis manuscript. Secondly, I would like to say thank you Amhara Region Agricultural
Research Institute (ARARI) and Ethiopia Agricultural Research Institute (EIAR) for giving
scholarship and financial support as well as Bahirdar University College of Agriculture and
Environmental Science.
I also extend my thanks to all staff members of Adet, Sirinka and Fogera Rice Research
and Training Centres for helping directly or indirectly during the implementation of this
research work.
Finally, I would like to express my love and passion to my wife, children, brothers, sisters
and friends who gave courage and hospitality during the study period.
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DEDICATION
This thesis is dedicated to my beloved family for their unwavering support, and for their
encouragement for everything follow up in my whole academic career, and for my life for
all success.
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TABLE OF CONTENT
Contents Page
THESIS APPROVAL SHEET Error! Bookmark not defined.
DECLARATION iii
ACKNOWLEDGEMENTS iv
DEDICATION v
LIST OF TABLES ix
LIST OF APPENDIX TABLES xii
LIST OF ABBREVIATIONS/ACRONYMS xiv
CHAPTER 1. INTRODUCTION 1
1.1. Background and Justification 1
1.2. Statement of the Problems 3
1.3. Objectives of the Study 4
1.3.1. General objective 4
1.3.2 Specific objectives 4
2.1. Mango, Origin, Taxonomy, Ecology 5
2.1.1. Mango origin and taxonomy 5
2.1.2. Ecology of mango 6
2.1.3. Management of mango tree 7
2.1.4. Mango production constraints 8
2.2. White mango scale origin, Taxonomy, Biology and Ecology 9
2.2.1. White Mango Scale origin and taxonomy 9
2.2.2. Biological characteristics of white mango scale 10
2.2.3. Ecology of white mango scale 12
2.2.4. Distribution of white mango scale 14
2.2.5. Host ranges of white mango scale 16
2.2.6. Sign and symptom of white mango scale 16
2.2.7. Damaging and economic impact of white mango scale 17
2.3. Management of white mango scale 19
2.3.1. Cultural and agronomical method 19
2.3.2. Biological control method 21
2.3.3. Use of tolerant mango variety 22
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TABLE OF CONTENT (continued)
2.3.4. Chemical control method 23
2.3.5. Integrated white mango scale practice 25
3.1. Assessment of White Mango Scale 26
3.1.1. Description of the survey area 26
3.1.2. Study design and sampling size 28
3.1.3. Procedures of survey work 29
3.2.1. Description of the experimental site 30
3.2.2. Insecticides and experimental design 30
3.2.3. Procedure of the study 31
3.3. Data collection 34
Response of the growers (%): About white mango scale infestation level, and the status of
mango tree plantation measured in each kebele in percent form. 34
3.3. Statistical data analysis 34
3.3.1. Analysis of survey 34
3.3.4. Experimental data analysis 36
CHAPTER 4. RESULTS AND DISCUSSIONS 37
4.1. Survey of White Mango Scale 37
4.1.1. Demographic characteristics of the respondents 37
4.1.2. Mango tree plantation status 38
4.1.3. White mango scale infestation and their perception 38
4.1.4. Growers response about pruning of mango tree 39
4.1.5. Agronomic practice of mango tree 40
4.1.6. Growers mango seedling source 41
4.1.7. Controlling practice of white mango scale 42
4.2. Assessment of White Mango Scale in mango orchards 43
4.2.1. Incidence, prevalence and severity 43
4.2.2. Mango variety and white mango scale infestation 43
4.2.3. Alternative host identification 45
4.3. Field Experiment 46
4.3.1. Severity of white mango scale on each phenology of mango tree 46
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TABLE OF CONTENT (Continued)
4.3.2. Severity of white mango scale in each growth of mango 46
4.3.3. Seasonal fluctuation of white mango scale 47
4.3.4. Screening of tolerance mango variety 48
4.3.5. Mango tree spacing and the severity of white mango scale 49
4.3.6. Effects of insecticides on white mango scale 51
4.3.7. Effects of insecticides on white mango scales mortality 52
5.1. Conclusions 54
5.2. Recommendations 54
REFERENCES 55
APPENDICES 70
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LIST OF TABLES
Tables Page
Table 4.1. Demographic characteristics of the respondents in Bahir Dar Zuria District from
2020/2021 cropping season 37
Table 4.2. Mango growing experience and the status of mango plantation in Bahir Dar
Zuria District from 2020/2021 cropping season 38
Table 4.3. White mango scale infestation and Perception of the respondent about the
infestation in Bahir Dar Zuria District during 2020/2021 cropping calendar 39
Table 4.4. Response of producers about pruning practice of mango tree in Bahir Dar Zuria
District during 2020/2021 cropping season 40
Table 4.5. Cultural practice of mango tree in Bahir Dar Zuria District from 2020/201
Cropping season 41
Table 4.6.Growers mango seedling source in Bahir Dar Zuria District during
2020/2021Cropping season 42
Table 4.7. Growers controlling practice of white mango scale infestation in Bahir Dar Zuria
District during 2020/2021 cropping season 42
Table 4.8. Infestation status of white mango scale in Bahir Dar Zuria District during
2020/2021 Cropping calander 43
Table 4.9. Cropping system of mango tree in Bahir Dar Zuria District from
2020/2021cropping season 44
Table 4.10. Alternative hosts of white mango scale in Bahir Dar Zuria District from
2020/2021cropping season 45
Table 4.11. Phenology of mango tree and the severity of white mango scale in Bahir Dar
Zuria District from 2020/2021 Cropping season 46
Table 4.12. Growth phase of mango tree and the severity of white mango scale in Bahir
Dar Zuria District from 2020/2021 cropping calander 47
Table 4.13. Mean fluctuation of White Mango Scale from August1/ 2020/September
1/2021 in Bahir Dar Zuria District cropping calander 48
Table 4.14. The severity of white mango scale in each mango variety in Bahir Dar Zuria
District from 2020/2021 cropping season 49
Table 4.15. The severity of white mango scale in each spacing of mango tree in Bahir Dar
Zuria District from 2020/2022 cropping season 50
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LIST OF TABLE (continued)
Table 4.16. The number of white mango scale colonies pre and post application of
insecticides in Bahir Dar Zuria District during 2020/2021 cropping season 52
Table 4.17. Mean mortality of white mango scale colonies in Bahir Dar Zuria District from
2020/2021 cropping season 53
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LIST OF FIGURES
Figure Page
Figure 2.1. Mango white scale biology 12
Figure 3.1. Location map of the survey site 28
Figure 3.2. Location of the experimental site 30
Figure 3.3. The avoiding mechanism of producers after pruning the infected branch 40
Figure 3.4. Host plants of white mango scale
Error! Bookmark not defined.
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LIST OF APPENDIX TABLES Appendix Table Page
Appendix Table 1.Base line survey questionnaire 70
Appendix Table 2.Anova tables of severity in each phenology eggs 71
Appendix Table 3.Anova table of crawlers in phenology of mango tree 71
Appendix Table 4.Anova table of adult white mango scale 71
Appendix Table 4.Anova of mango growth phase and severity 72
Appendix Table 5.Anova table of Seasonal fluctuation of white mango scale 72
Appendix Table 6.Anova table of tolerant mango variety leaf parameters 72
Appendix Table 7.Anova tables of on stem parameters 72
Appendix Table 8.Anova table of fruit of mango tree 72
Appendix Table 9.Anova tables of inflorcence of mango tree 72
Appendix Table 10.Anova tables of petiole of mango tree 72
Appendix Table 11.Anova table intra and inter row spacing of mango tree 72
Appendix Table 12.Anova table before spraying of the insecticides 73
Appendix Table 13.Anova table after 1st spraying of the insecticides 73
Appendix Table 14.Anova after 2nd spraying application of the insecticides 73
Appendix Table 15.Anova table of mortality of white mango scale after 1st 73
Appendix Table 16.Anova table after second application 73
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LIST OF APPENDIX FIGURES
Appendix Figures Page
Appendix Figure 1. Process of host plant of white mango scale identification 73
Appendix Figure 2. Host plants of white mango scale identified 74
Appendix Figure 3. Mango varieties adopted in the farm of mango 74
Appendix Figure 4. Experimental site and tested chemicals 75
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LIST OF ABBREVIATIONS/ACRONYMS
AD Anno Domini
ARARI Amhara Regional Agricultural Research Institute
BBCH Biologische Bundesanstalt, Bundessortenamt
and Chemische Industrie
BoA Bureau of Agriculture
CABI Centre for Agriculture and Bioscience International
CSA Central Statistical Agency
EC Emulsifiable Concentrate
FYM Farm Yard Manure
GLM General Line Model
IPM Integrated Pest Management
MCDM Multi-Criteria Decision Making
MoA Minister of Agriculture
MORD Minister of Agriculture and Rural Development
NMA National Meteorological Agency
WMS White Mango Scale
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Assessment and Management of white mango scale (Aulacaspise tubercularis) on mango
(Mangifera indica L.) In Bahirdar Zuria District, North Western Ethiopia
ABSTRACT
Mango (Mangifera indica L.) is the second perennial fruit crops in Ethiopia in its coverage
and economic importance. However, this fruit crop is constrained by white mango scale.
Therefore, this study was conducted to assess the status the infestation, and to evaluate
synthetic insecticides as management option in Bahir Dar Zuria District, Ethiopia during
2020/2021 cropping season. The method of the study was through structured questionnaire
and assessment of the orchards. The sampling techniques were purposive for the selecting
study sites, households as well as mango orchards. For this study, about 3 study sites, and
33 mango growers or orchards from each site were selected. The data collected includes
white mango scale status and host plants. The collected data was analyzed using SPSS and
STATA software. The prevalence as well as the incidence of white mango scale was 100%
while the severity was about 80.76%. Other than mango, white mango scale was occurred
on guava, lime, and orange and eucalyptus forest tree. The maximum severity of white
mango scale was 71.7 on 1m*1m inter - and intera row spacing while the minimum severity
(41.43) was recorded on 6m*6m spacing. The screening of insecticides as well as tolerant
mango variety was carried out at Zenzelima. From the screened tolerant mango variety,
Tommy Atkins was the tolerant mango variety with the lowest severity recorded as 31.7,
34.2, 23.7, 13.6 11 and 24.4 respectively on the leaf, stem, inflorcence, fruit and petiole of
mango tree. For the evaluation of insecticides, there were four treatments namely
Nimbecidence 3% EC, Karate EC 5%, Folmit 40% EC and untreated. The design of the
experiment was Randomized Complete Block Design with three replications. Insect’s data
were collected, and counted from 20cm twigs from 12 mango tree. The data was analyzed
using SASv23 software. Nimbecidence 3% EC insecticide control better than others. The
mortality rate of white mango scale using Nimbecidence 3% EC in the 1stand 2nd spraying
was 70.71 and 44.2 respectively, which is the highest compared to others. Therefore, it is
recommended to apply Tommy atikine mango variety, 6m*6m intra and inter row plant
spacing, and Nimbecidence 3% EC insecticide for the controlling of white mango scale in
the study area.
Keywords: Host, Mango, Nimbecidine, Prevalence, Spacing, white mango scale
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CHAPTER 1. INTRODUCTION
1.1. Background and Justification
Mango (Mangifera Indica L.) belongs to the Anacardiaceae family, which includes the genus
indica. The only species farmed commercially on a considerable scale is indica (Griesbach,
2003). Mango is a fruit that originated in tropical Asia and is now found in tropical and
subtropical lowland areas all over the world (Mukherjee and Litz, 1997; Dirou, 2004 and Crane
et al., 2008). In the tropics and subtropics, mango is a very important fruit crop (Singh, 1986).
Mango trees are erect and fast-growing trees with a canopy that can be broad and rounded or
more upright (Schnell et al., 2006).The tree is a deep-rooted, evergreen crop with the potential
to grow into massive trees. Mango is taproot descends to a depth of 20 feet, producing several
wide-spreading feeder roots as well as many anchor roots that penetrate for several feet
(Matsuoka, 2000). Mango tree is young, short-pointed, oblong and lanceolate. This crop has
the shape and measuring more than 30 cm in length and up to 13 cm in breadth, mango tree
leaves are simple, whole, leathery, dark green and glossy, pale green or red. The mango tree is
inflorescence is a branching terminal panicle that measures 4–24 inches in length and bears
500 to 10,000 flowers (Salim et al., 2002).
Mango is a very important fruit crop in the world. The crop is grown in over 85 countries with
a total production area of roughly 3.69 million hectares. The production was estimated to be
over 35 million tons per year worldwide (FAO, 2019). Mango output increased by 100 %
globally between the years 1971 and 2002 with production estimated at roughly 25.75 million
tons in 2002 (FAO, 2020).In Ethiopia, Mango fruit yield is large, and having the potential for
internal, and export markets as well as industrial processing (Takele Honja, 2014). According
to the Central Statistical Agency 2020 (CSA) estimate, the total production coverage was
around 1.08 million km2 .The total fruit production area coverage was about 107,890 hectares
(FAO, 2020).
Even though, Mango is the second most important fruit crop with the 1,857,387 households
contribute to mango production, which produces roughly 185,739 tons of mangos per year from
15,413.76 hectares. Despite the fact mango fruit cultivation has historically been important in
Ethiopia and the Amhara region, biotic and abiotic factors are presently limiting production
central statical agency (CSA, 2017).
Lack of inappropriate cultural practices which including planting pattern, planting system,
supplementary irrigation, lack of optimum rate of fertilizer application, lack of improved
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tolerant mango variety, varietal mixture, absence of proper mango pruning practice and
unavailability of high quality planting materials were some of the abiotic factors (Gashawbeza
Ayalew et al., 2015; Tewodros Bezu et al., 2015).
Insect pests are some of the most critical biotic limiting factors for mango production. White
mango scale is one of the most common insect pests of mango trees. This insect pest is also
one of the most critical insect pests of mango fruit crops (Griesbach, 2003). The first report of
white mango scale insect pest infestation in Ethiopia was in 2010 in a mango orchard owned
by Green Fосus Ethiopia (Abo-Shanab, 2012). That was utilized to import mаngо seedlings
from India, and it has been deduced that insect pests may have reached Ethiopia by chance on
those seedlings (Abo-Shanab, 2012).
White mango scale is economic importance, and has been claimed to have a negative impact
on mangoes in various places of the world, including Ethiopia (Germain et al., 2010; Ofgaa
Digitra and Emana Getu, 2015).This insect pest is imperfect metaphoresis that means the insect
lacks pupal stage in its life cycle. White mango scale has polyphagous feeding habit which is
used two family vascular plants as its host (Germain et al., 2010).
The female armour is circular, flat, thin, and often wrinkled, and exuviae is near the margin,
and yellowish-brown, with a median black ridge, forming a dark distinct median line while
male armour is circular, flat, thin, and often wrinkled, and exuviae is near the margin, and
yellowish-brown, with a median black ridge, forming a dark distinct median line. Male armours
are small, white, and tricarinate, with sides that are nearly parallel. Crawlers are a rich vivid
brick red (Hodges and Hamon, 2006).
Currently, there was no quantifying the status of this insect and plantation status of mango tree.
Also there was no single insecticide, variety and spacing of mango has been authorized in the
early 1980s. Insecticides similar to those used to control white mango scale infested mango
were recommended for the control of Hemiptera insect scales like that of the red scale
(Aonidiella auranti) on citrus (Tsedeke Abate, 1994).
Several trials on white mango scale and insecticides demonstrated that Imidacloprid%SC,
Thiamethoxam 25%WG, Dimethoate%, and Lambda cyhalothrin17.5% SC were developed
and registered for the control of white mango scale (Andrew Manners, 2016; Parakash and
Patil, 2018). Meanwhile, insecticides such as Movento 150 OD, Methidathion 400 EC, and
Folmit 500 SL were developed in Ethiopia to suppress white mango scale (Gashawbeza
Ayalew et al., 2015; Ofgaa Djirata et al., 2016).
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According to Ferdu Azerefegne et al., (2009) and Ofgaa Djirata, (2017), there have been few
reports of insecticide screening against the white mango scale insect pest in Ethiopia since the
white mango scale was introduced in the country less than 10 years ago. Imidacloprid % SC,
Thiamethoxam 25% WG, Dimethoate 40%, and Lambda cyhalothrin 17.5% SC are some of
the insecticides (Andrew Manners, 2016; Parakash and Patil SB, 2018). In particular,
insecticides such as Movento 150 OD, Methidathion 400 EC, and Folmit 500 SL were
developed in Ethiopia to control white mango scale (Gashawbeza Ayalew et al., 2015; Ofgaa
Djirata et al., 2016).
As a consequence, there was very little available information on effective management options
for eliminating white mango scale in the Amhara region of the Bahirdar Zuria District mango
potential area. Apart from that, regular pest assessments will tell us the status of white mango
scale occurrence, distribution and its impact of on mango tree. Also the study indicates farmer’s
knowledge and pest control practices.
1.2. Statement of the Problems
Mango trees in Bahirdar Zuria District, Amhara Region, North Western Ethiopia, were just
being negatively affected by white mango scale. According to Temesgen Fita (2014) studies,
the yield obtained before white mango scale emergence was significantly higher than the yield
obtained after white mango scale emergence, regardless of the infested Districts. Mohammed
Dawd (2012) also mentioned that before the emergence of white mango scale, fruit harvest was
up to one ton, but then after the occurrence of white mango scale, fruit harvest was decreased
to 0.2 to 0.3 ton or nothing at all.
The appearance of white mango scale in the District as well as its increasing prevalence to
other nearby mango fields in the study region had a massive effect on mango tree plantation
and yield. Due to the infestation pressure of this insect pest in the area, the insect caused mango
panicle destruction and loss of quality and market.
Also, newly planted mango trees were uprooted due to an infestation of white mango scale and
the plantation status of mango trees in the study area declines from time to time. Hence, this
study was carried out with the aim of to understand the status of mango and develop
management option for the white mango scale.
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1.3. Objectives of the Study
1.3.1. General objective
To assess and develop management option for white mango scale in Bahirdar Zuria
District, North Western, Ethiopia
1.3.2 Specific objectives
To assess the plantation status of mango, and white mango scale infestation.
To assess alternative host ranges and tolerant mango variety for white mango scale.
To evaluate synthetic insecticides for the management of white mango scale.
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CHAPTER 2. LITERATURE REVIEW
2.1. Mango, Origin, Taxonomy, Ecology
2.1.1. Mango origin and taxonomy
Mango (Mangifera indica L.) is an important perennial tropical fruit crop. This perennial fruit
crop is a prized dietary component (Rocha Ribeiro et al., 2007). Mango tree is thought to have
originated in the region between north-east India and Myanmar (Samson, 1986; Yadav and
Singh, 2017). This tropical fruit crop is found under the categories of Kingdom plantae, class,
Mangoliopsida, phylum, magnoliophyte, order, Sapindales, family Anacardiaceae, genus
mangifera, and the species indica are the taxonomic classifications for mango tree (Wauthoz
et al., 2007).
This fruit crop is consumed as a fresh fruit crop. The fruit of mango has many forms of
preparations (Nabil et al., 2012). It is also utilized in animal feeds, poultry diets,
Ethnopharmacology, and a variety of chemical businesses around the world (Wauthoz et al.,
2007; Kayode and Sani, 2008). Mango fruit has a rich, fragrant aroma and a flavor that is
pleasantly balanced between sweetness and acidity (Hobson and Grierson, 1993).
Mango fruit is mature, the skin is usually a mix of green, red, and yellow colors, depending on
the variety (Matsuoka, 2000). The flesh of mango is bright orange and tender with a wide flat
pit in the middle (Ben-Dov, 2012). It has attractive color, sweetness, excellent flavor, delicious
taste, high nutritional value and health promoting qualities (Fowomola, 2010). Mango fruit has
high amount of sugar, protein, fats, and all known vitamins. Moreover, it is an excellent source
of dietary antioxidants such as ascorbic acid, carotenoids, and especially phenolic compounds
(Nabil et al., 2012).
The mature leaves of mango tree are simple, entire, leathery, dark green and glossy, pale green
or red while the young, short-pointed, oblong and lanceolate in shape and relatively long and
narrow and measuring more than 30 cm in length and up to 13 cm in width (Salim et al., 2002).
The inflorescence of mango tree is a branched terminal panicle 4–24 in length. The inflorcence
has the capability of bearing what has been variously estimated to range from 500 to 10,000
(McGregor, 1976, 200 to 6000 Free, 1993), and 1000 to 6000 (Mukherjee, 1953). The flowers
of mango tree are borne collectively on panicles. Individual mango flowers are small ranging
in size from five to ten mm in diameter (Scholefield, 1982; Mukherjee and Litz., 1997).
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The number of panicles of mango range from 200 to 3000 per tree depending on tree size and
extent of branching. Mango trees are often irregular in their cropping habit with no clear pattern
across different years and place. Plantings system of mango can also suffer from alternate or
biennial bearing of fruit where a tree or an orchard produces a large fruit crop in an on-year
followed by a small crop in the following off-year (Souza et al., 2004). There can be periods
of irregular bearing of mango and periods of alternate bearing in the same orchard (Fitchett et
al., 2016).
Mango trees are monogenic, and polygenic which bears both perfect and hermaphroditic
genetic nature. Flowers having both pistil and staminate structures are purely male or staminate
flowers. Both types of flowers are born on same inflorescence, and it is monoicous fruit crop
(Mukherjee and Litz, 1997). Knight (1997) reported that as mango fruit matures in 100 to 150
days after flowering and the fruit will have the best flavor if allowed to ripen on the tree.
Griesbach, (1992) reported that commercial marketability requires 13 % dissolved sugars and
the fruit ripens best on the condition placed stem end down in trays to prevent the sap from
spreading to other parts of the fruit and also to encourage even ripening at room temperature
20-25°C and covered with a dampened cloth to avoid shriveling, and that loss of fruit increases
dramatically after harvest as the fruit maturity increased (Bautista-Rosales, 2005).
Mango trees which grown in most parts of Ethiopia developed from seedlings, and they are
inferior in productivity in terms of fruit quality. Considering this, the inferior quality trait of
mango, improved mango varieties named Kent, Keitt, Tommy Atkins and apple were
introduced from Israel in 1983 and are being commercially produced by the Upper Awash Agro
industry enterprise and distributed in to different parts of the country (Mohammed Dawd et al.,
2012; Temesgen Fita, 2014).
2.1.2. Ecology of mango
The mango species can grow successfully from sea level up to 1200 meters above sea level.
The production and productivity of mango tree varied according to elevation, altitude, and
temperature. Mango has indeed been successfully developed in a wide range of climates from
hot and humid to cool and dry or arid, with mean annual rainfall of 400mm to 3600mm. The
crop grown in the temperatures of at least 21°C with an optimum of 25°C (Bally, 2006). This
tree is drought tolerant and may survive with very little as 300 mm of yearly precipitation
(Johnson et al., 1997; Al-Kazafy, 2015).
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2.1.3. Management of mango tree
Proper spacing of mango trees is crucial for all the tree physiological functions (Dirou, 2014).
The production of mango is hindered whenever adequate spacing, also which is not maintained,
and the pest outbreaks are more likely to happen (Seid Hussen and Zeru Yimer, 2013). Mango
tree spacing appears to be an essential consideration in production, and the pest management
according Olaniyan (2004). Mango trees can grow to be massive examples, orchards are
typically planted with a field condition and a lower population density (Khan et al., 2015).
Overpopulation of mango trees in cultivation of mango tree resulted in fewer fruits. When the
tree become more populated, the insect become more prone to be damaged and pest-infested
the tree. Tall trees can pose a harvesting challenge and make spraying and pruning exceedingly
difficult (Griesbach, 2003). Study showed that mango fruits grown in high-density planting
had a progressive decline in crop yield after 14–15 years (Sharma et al., 2006).
Since commercial fruit cultivation on a small scale in Ethiopia is indeed a floral crop,
agronomic procedures in nurseries and orchards of different fruit crops rely heavily on human
labor. Having the right tools, knowing how to use them, and making management decisions
about horticultural tools and equipment, practice selection, market availability, and storage
facility availability, among other things, are all important factors that can affect horticultural
operations and profits in a number of different ways (Andrew Manners, 2019).
Regular annual pruning is important for very well mango orchard. Pruning of mango tree is
maintaining of mango tree canopy size. Maintaining of mango canopy allows the entrance of
air and sunlight to penetrate mango tree (Bally, 2006). In Ethiopia, a significant portion of
mango growers utilize river water, even if only a significant fraction of smallholders uses
pound water. Mango yields are higher in river water irrigation than in pond water irrigation.
One of the parameters that determines mango yield is the quantity and quality of accessible
water. The amount and frequency of irrigation required is determined by a variety of variables
including soil type, property, climate, and others (Seid Hussen and Zeru Yimer, 2013).
The use of organic and inorganic fertilizers for the mango production purpose is rare except
some innovative farmers that use organic fertilizer. Similar study conducted by Ayelech
Tadesse, (2011) indicated that farm yard manure principally transported from homestead to the
field mostly during the dry season and spread in the bottom of each tree in circular form.
Fertilizer treatment, irrigation, pest and disease control, wind break, and trimming are among
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the mango production strategies used by smallholder farmers in the area, according to the same
study (Rosals et al., 2005).
Chemical inputs were entirely exploited neither for fertilization nor for pest treatment,
according to the assessment research report. According to different studies, smallholder
farmers in the area intercrop mango with maize, taro, ginger, chat, cabbage, and banana at
various phases of development, along with annual and perennial crops (Tesfaye Hailu et al.,
2014).
Collecting of mango tree by hand picking, scissor cutting, and stick harvesting are the methods
used mostly by smallholder farmers in Ethiopia. Hand picking is indeed a way of gathering
produce that preserves the quality of the fruit while also protecting it from mechanical damage.
It produces fruit with a stem, which reduces bruising and damage, whereas stick structures
enable fruit to drop and leave the fruit without a stem, which increases bruising and mechanical
damage to the fruit. Ayelech Tadesse (2011) demonstrated that harvesting typically begins after
fruit dropping, which is the primary maturity indicator, indicating that cuts, punctures, and
bruising boosted ethylene production and expedited fruit softening, resulting in mechanical
injuries and decay (Seid Hussen and Zeru Yimer, 2013).
2.1.4. Mango production constraints
Mango fruit production constrained by several factors. That means lacks of pest tolerant
improved mango variety, lack of proper agronomic practices, prevalence of wind and bird’s
postharvest loss and poor marketing and outbreak of pest with relation to the climate change
(Seid Hussen and Zeru Yimer, 2013; Tewodros Bezu, 2015).
The other constraints of the production of mango according to different research findings were
insect and disease pest. From diseases such as Anthracnose, Bacterial Black spot, stone and
from insect pests’ weevil (Sternochetus spp), fruit fly, mango gall flies, Mango leaf coating,
Mites, Mango seed weevil, Mealy bug, Powdery mildew, Scale, Spider mites, mango tip borer,
Stem-end rot, Termite, Thrips and White flies (Balock and Kozuma, 1963; Halteren, 1970;
Griesbach, 2003 and FAO, 2010).
In Ethiopia, the production and productivity of mango was constrained by insect pests such as
fruit flies, mango seed weevil, mites, thrips, mealy bugs and scale insects and reported to have
caused damages ranging from significant vegetative damage to total mango yield losses (Seid
Hussen and Zeru Yimer, 2013 and Alemayehu Chala et al., 2014). Moreover, Tewodros Bezu
et al., (2015) reported thrips, fruit flies, termites, and various fungal diseases constrain mango
9
production in Ethiopia, from the insect pests of mango, white mango scale was the most
important insects which was reported to have damaged mango in various parts of the world
(Cunningham, 1989; SRA, 2006; Germain et al., 2010 and Abo-Shanab, 2012).
White mango scale was among insect pests inflicting damage to mango trees in Amhara region
Bahirdar zuria District in Amhara Region, Western Ethiopia. The study finding of Temesgen
Fita, (2014) indicated that, infested Districts by white mango scale, the yield obtained before
white mango scale emergence was significantly higher than after white mango scale
emergence. Mohammed Dawd, (2012) also reported that fruit harvest up to one tons before the
occurrence of white mango scale decreased after the occurrence of mango white scale.
Literatures reported regarding the impact of white mango scale, and losses caused by fruit
rejection from Nayarit due to white mango scale infestation were ranged from 50 to 100%
(Hodges and Harmon, 2006).
2.2. White mango scale origin, Taxonomy, Biology and Ecology
2.2.1. White Mango Scale origin and taxonomy
White mango scale is an insect whose common names are cinnamon scale, mango scale, white
mango scale, escama Del mango, escama Blanca del mango. This insect was known by its
accepted name Aulacaspis tubercularis New stead in 1906 (Varshney et al., 2002). This insect
pest commonly known as armored scale insects, as one of the most species in the families and
it is composed of 2650 species in 400 genera (Osuna-García et al., 2016; Ben-Dov, 2012).
The feeding nature of White mango scale is polyphagous armored scale. The insect is
considered as one of the key pests of mango crops around the world (Llewellyn, 2000). It
produces conspicuous pink blemishes on the mango fruits, which depreciate their commercial
value, and it makes them unacceptable for export markets. In the absence of control measures,
the pest could cause up to 90% yield losses in mango groves, and which may pose a threat to
sustainability mango production (Hodges and Harmon, 2006).
The pest reproduces during both dry and wet seasons (Halteren, 1970). White Mango Scale
was a sucking insect that poses severe threat to mango plantations in various mango growing
countries (Labuschagne et al., 1996; Pena et al., 1998 and Juárez-Hernández et al., 2014).
The feeding nature of white mango scale is sap-feeding insects which injure plants directly by
depriving the plants of its food and water supply (Pellizzari and Germ, 2010). Indirect damage
of white mango scale is by gall formation, foliage disturbances such as bleaching or yellowing,
10
and deformation such as leaf curling. Generally, however, the effect of sucking insects upon
trees is much less conspicuous than the effect of defoliators (Juárez-Hernández et al., 2014).
The damage caused by White Mango Scale included yellowing of leaves, appearance of
conspicuous pink blemishes on mature and ripe fruits, and dieback of the plant (El-Metwally
et al., 2011 and Abo-Shanab, 2012). Infestation in young trees might lead to excessive fall off
leaves, retarded growth and death of the whole plant (Nabil et al., 2012).
This insect pest caused economic problem on mangoes in most mango potential continents and
their countries. The ultimate economic impact of this insect pest could range from low to high
depending on the targeted market (local versus international) and part of mango infested
seedling, leaves and fruits (Daneel, and Joubert, 2009; Urias-López et al., 2010).
The insect pest was reported in most of the mango producing zones in African countries.
However, Majority of the farmers still do not know it nor consider it as a pest Likewise, the
incidence and impact of white mango scale in Ethiopia in Amhara region of white mango scale
has spread in all mango producing area has become problem of mango and to alleviate this
insect effect, there were several management options those were available for this insect pest
(Ofgaa Djirata et al., 2016).
2.2.2. Biological characteristics of white mango scale
White mango scale is a sessile armored, tiny shelled insect which belonging to the Hemiptera
order as well as the Diaspididae family (CABI, 2019). It is swollen angular, quadrate, prosoma
body, wide at conspicuous lateral tubercles in approximately level with anterior spiracle and
posterior spiracles usually associated with spiracle pores; gland spines and macro ducts absent
from thorax and head; circular, flat, thin, and wrinkled with opaque white shells (Moharum,
2012; Harmon, 2016).
Male white mango scales were tiny, white, and tricarinate, with nearly parallel sides. The body
of the white mango scale is broadest at prominent lateral tubercles, almost level with anterior
spiracles, and posterior spiracles are part of the growing with spiracle pores and gland spines,
and macro-ducts are absent from the thorax and head whenever mounted on a plate with an
angular prosoma (Soysouvanh and Hong, 2016). The white mango scale is a circular, flat, thin,
wrinkled adult male insect. Exuviae are yellowish-brown and have a median black ridge which
produces a dark prominent median line near the margin (Meyer and Whitlow, 1992). Male
covers acquire a reddish brown color and take on a more elliptical shape as they mature into
11
pre-pupal, pupal, and adult generations. For males, the second instar lasts 5–8 days (Williams,
and Watson, 1988).
The female scale cover is just about spherical, white, and transparent, with black, oval exuviae,
whereas the male scale cover is smaller, rectangular, white, and also has three prominent
longitudinal ridges exuviae (New Zealand, 2018). Food availability impacts white mango scale
sexual reproduction, but the sex ratio is typically 1:1 (male: female), though both male and
female colonies have been observed (Ahmad and Ghani, 1972).
Adult females of the white mango scale deposit 28–65 eggs in concentric circles underneath
the scale cover over the duration of 11–13 days, and might even produce 3 or 4 batches in
their lifetime (Gilbert, 1985). The white mango scale has a general look, and mature female
white mango scales can lay 80-200 eggs (Sayed, 2012). Females stay pale yellow, round and
somewhat visible in the second instar, which lasts for 8–10 days. Females nymphs are 0.6–1.1
mm long (Williams, and Watson, 1988).
Smooth, elongate, and whitish when it was first laid, eggs start turning pale yellow as they
mature. The eggs are placed behind the scale layer that surrounds the female's body. The
average egg length and breadth are 0.22 mm and 0.09 mm, respectively (Salahuddin et al.,
2015). The eggs hatch in eight days generating red-orange nymphs or crawlers that move to
branches, leaves, and flowers and attach themselves to feed on plant tissue where they grow
and reproduce (Bautista-Martinez, 2006). White mango scale crawlers are light green to
yellowish brown in color, translucent, and rectangular in shape, measuring 0.23 mm in length
and 0.11 mm in width (Salahud din et al., 2015).
Nymphs of white mango scale may emerge after that the female has begun depositing the next
batch of eggs (personal observation). About 80% of the crawlers of newly hatched nymphs'
white mango scale (also known as crawlers) become males The newly hatched nymph of WMS
is very small, elongate, oval, and completely devoid of any wax secretion, and the crawler
moves there until it finds a suitable place to settle on. Legs, antennae, and a pair of bristles at
the tip of the abdomen move over the leaf surface for 2–48 hours to find a feeding site, and the
crawler is free moving and recognized by the presence of legs, antennae and wings (Halteren,
1970).
The crawlers were deep bright red. The life cycle of white mango scale took between 35– 40
days for females and 23 – 28 days for males (Halteren, 1970). Depending on temperature
females lay 80 to 200 eggs and crawlers moved to feeding sites settling within 24 hours after
12
hatching. Male crawlers settled in groups close to females and female crawlers settled
randomly Up to 80% of crawlers become males in nurseries, infestation at early stage retards
growth of seedlings (Halteren, 1970).
After settling, females remain sessile throughout their development and Females released
pheromones through their anus to attract males (Moreno,1972) and adult males undergo a
pseudo-pupation, develop a pair of wings and can disperse by flying to find mates (Ghauri,
1962). The male pre-pupal and pupal stages are spent under the scale produced by the second
instar. The insect pest could produce five to six generations per year at a maximum day time
temperature of 26°C and night time minimum of 13°C (Miller and Davidson, 2005).
White mango scale was a pest that is present all year round-with overlapping generations.
Overlapping generation is growing the population within the same year. Increasing of the
generation of white mango scale damages organs of mango tree by feeding the parenchyma.
(Miller et al, 2005).
(A. tubercularis): A=A group of male covers with one female cover (lower right); B=High resolution
female white cover=High resolution male and female white scale
Figure 2.1. Mango white scale biology
2.2.3. Ecology of white mango scale
Weather is an important parameter that affects white mango scale distribution, abundance and
their management. According to Dharmendra et al. (2014) favorable weather condition for
13
high pest infestation ranges between 24-35°C and relative humidity 70-95% in both mango
orchards. Abo-Shanab (2012) reported a significant positive relationship between daily mean
temperature and relative humidity, and recorded population density of white mango scale. On
the other hand, the author reported a significant negative relationship between wind speed and
dew point, and population density of white mango scale which may be due to transference of
insect crawlers and early nymphal instars by the wind to another plants and/or places
(Dharmendra et al.,2014)).
White mango scale can produce five to six generations per year at a maximum day time
temperature of 26°C and night time minimum temperature of 13°C (Miller and Davidson,
2005). Weather is an important factor determines white mango scale distribution, abundance
and their dominance. According to Dharmendra et al., (2014) favorable weather condition for
high pest infestation ranges between 24-35°C and relative humidity 70-95% in both mango
orchards (Salem et al.,2015).
Studies reported as that has significant positive relationship between daily mean temperature
and relative humidity and recorded population density of white mango scale. On the other hand,
Literatures reported a significant negative relationship between wind speed and dew point and
population density of white mango scale which may be due to transference of insect crawlers
and early nymphal instars by the wind to another plants and/or places (Abo-Shanab, 2012).
The study on effective temperature requirement of scale (Hemiptera: Diaspididae) by
González-Zamora et al., (2012) reported that the first and second stage nymphs and young
female individuals require 24.4,11, and 13.2 days to complete their developments at 25°C
while showed no development at 30°C (Wong et al., 2008). Thus, it is possible to say that
Aulacaspise tuber cularise is more susceptible against seasonal and global temperature. Studies
conducted a two-sex life table study of white mango scale (Hemiptera: Diaspididae) at
20,23,25,28, and 31°C the intrinsic rate of increase under these temperatures was 0.06,
0.07,0.09, 0.10, and 0.08 d-1 (Ravuiwasa et al., 2012).
The same types of studies reported in the same ways as global warming modified
environmental conditions of different regions because of an increase in greenhouse gas
emissions, particularly temperature, rainfall, and relative humidity (Netherer and Schop
2010).The phenomenon generated changes in population development, and the ecology of
diverse plant, and animal species, thus favoring displacement of diverse pests and diseases to
14
other locations, an important problem in terms of pathogens such as fungi, bacteria, and viruses,
as well as the vectors involved (Netherer and Schop, 2010).
White mango scale does well at warmer temperatures 25-28°C; however, lower temperatures
adversely affect its performance. In a study of the life cycle of white mango scale (Hemiptera:
Diaspididae), the preoviposition period first and second nymph stage periods, and ovipositional
period were recorded as 6-13,7-18,9-26, and 28-59 days, respectively at 22.5–25.5°C under
laboratory conditions (Abd El-Razzik, 2000).
White mango scale could produce five to six generations per year in a maximum day time
temperature of 26°C and night time minimum of 13°C (Miller and Davidson, 2005). According
to Sayed, 2012, the total population of white mango scale had maximum value 1006.89
individuals/leaf on June 15th at 15.2-28.40 C and 56.8% relative humidity. The lowest level was
in mid-December 39.80 individuals /leaf at 15.0-22.20 C and 55.6% relative humidity
(Deloatch, 1974). The mean numbers of nymphal adult female per sample unit were the highest
in mid-March as 343.75 and 147.66 individuals (Davidson, 2005).
The gravid female and prepupae and pupae stages reached their maximum as 129.94 and
694.31 on July 15th and April 15th (Kogan and Ortman, 1978). The lowest densities of nymphs,
and gravid female were 12.33 and 5.33 individuals on Mid-December whereas the least values
of adult female and pre-male 3.94 and 15.49 were observed in early September and mid-
November respectively. The total population had maximum value of 1095.65 individuals on
April 15th at 12.3-23.80C and 57.20% R.H. The lowest total population 58.30 individuals were
observed during Dec. 15th 38.72 individuals/leaf at 15.2-21.80 C and 56.3% RH (Owens,
2016).
The pest was abundance throughout the period extended from mid-February up to mid-
September while it was lower in abundance from early October up to early February (Sayed,
2012).White mango scale females and males were randomly distributed on leaves, stems and
fruit in mango orchards under organic and conventional management although males were
grouped in colonies of a few individuals to more than 100, which eventually allows them to
occupy the entire leaf in depending on the season (Urias-López et al., 2010).
2.2.4. Distribution of white mango scale
White mango scale distributed more than 43 countries in tropical and subtropical countries,
Oceania, South America, the Caribbean, and Asia, where it feeds on more than 40 plant species
(Malumphy, 2014; Stocks and Pena, 2013). According to Hodges and Harmon, (2006), the
15
distribution of white mango scale in the world classified in different agro ecological zones with
the variability of ecology (Dinka et al., 2005).
After the occurrence of the insect pest, it was distributed to the other adjacent peasant mango
farm within a short period of time and infestation source once infested takes less time. At the
time of the infestation of white mango scale, most farmers were uprooted mango trees from
their farm due to lack of affordable management options since the pest was new for them. And
then, the infestation of pest has been speeded at an alarming rate into different districts (Ofgaa
Digrata et al., 2017), and the author shown the distribution of white mango scale from its first
observed into four directions. Once presence of white mango scale in the region, the pest
spreads more and more in the quickly manner because of its small body size and which makes
it easy to spread with fruits, seedlings, and even by the wind (Kondo Muñoz-Velasco, 2009).
This characteristic has made this pest to colonize most of the mango producing zones. Being
an invasive pest, the information about the pest and its management practices was less available
for researchers, policymakers, and farmers in the most region of mango potential area. In fact,
most research work in the region focused around assessing the distribution and population
dynamics (Tsegaye Babege et al., 2017; Teshale et al., 2019) with a few trying to answer
questions around management practices (Abo-Shanab, 2012; Gashawbeza Ayalew et al.,
2015).
The pest distributed over the air distances of 97, 98, 92 and 43 km to the east, south, west and
north directions respectively (Teshale et al., 2102). Study showed that white mango scale
distribution was expanded to the southwestern part of Ethiopia and considerably affecting
mango production and productivity and they recorded very low population density and the pest
free areas. The pest spreaded too many other neighboring districts including the mango
production belt in the area (Mohammed Dawd et al., 2012; Gashawbeza Ayalew et al., 2015).
The distribution of white mango scale in Western Oromia, East Wollega, spreaded quickly
from one mango growing area to another and now distributed to all Districts (2014).
Severity status of white mango scale in mango orchards was studied by Temesgen Fita (2014).
In central rift valley, more than seventeen Districts, over 200 hectares of mango orchard
infested by white mango scale recorded (Gashawbeza Ayalew et al., 2015). During 2020/2021
severity of White Mango Scale in South Western part of Ethiopia was very high except some
Districts were recorded from mid to very high infestation of white mango scale.
16
2.2.5. Host ranges of white mango scale
White mango scale had many alternative host plants with relation to the feeding nature of the
insect pest. This insect pest was mostly polyphagous species (Panda and Khush, 1995). And
they were more prone to become major pests when introduced to new areas because their wide
host range facilitates their establishment (Kosztarab, 1996; Stocks, 2013). White mango scale
was reported to have been 93 infesting plants other than mango in different countries
(Malumphy, 2014).
Plant species found under families Sapindaceae and Rutaceae served as host plants for white
mango scale (Sarwar, 2013). It was recorded mainly from hosts belonging to four plant
families: Palmae, Lauraceae, Rutaceae, Anacardiaceae, particularly on mangoes and cinnamon
(Miller and Davidson, 2005; Borchsenius, 1966). White mango scale species were polyphagous
(Kosztarab, 1996, Miller and Miller, 2003). Additional studies supported the idea as the insect
family Diaspididae (Hemiptera: Coccoidea) includes a number of important pests of wild and
cultivated plants (Beck, 1965).
The pest attacked common perennial crops and that included tropical fruits and ornamental
plants including banana, coconut, camellia, guava, mango, palm, papaya, breadfruit, ginger,
bird of paradise, sugarcane, ficus, apple, plumeria, avocado, citrus, grape, and palms, citrus,
papaya, avocado, ginger, cinnamon, and pumpkin (Dinca, 2017).Similar reports from several
countries indicated that white mango scale is a polyphagous pest that inflicts damage to many
host plants (Erichsen and Schoeman, 1992;Malumphy, 2014).
The first report of white mango scale infestation of mango in Ethiopia has now been near to a
decade (Mohammed Dawd et al., 2012). The insect pest spreaded and has caused damages to
mango production in western Ethiopia (Tesfaye Hailu et al., 2014; Temesgen Fita, 2014; Ofgaa
Djirata and Emana Getu, 2015; Urias-López et al., 2010).
2.2.6. Sign and symptom of white mango scale
The signs and symptoms of White Mango Scale in white mango scale fertilization taken place,
and the crawlers hatched out. The hatched white mango scale stage moved until they glue
themselves to the part of the plant. The insect stage developed, and remained sucking the juice
of the plant under their armors on the leaf of mango tree (Louw, et al., 2008). The insect sucking
by penetrating pattern of leaf. That pattern revealed as it could penetrate not only cell wall but
also the lignified xylem. The infested xylem materials leaving behind a reddish mass have been
17
phenolic acid. From infested mango leaves the slices followed the stylet bundle penetration
path through the leaf from the piercing site on the leaf epidermis (Goble et al., 2012).
Including oblique, and parallel orientations in relation to the leaf surface, the stylet bundle
changed directions several times depend upon entering the spongy mesophyll (Juarez, et al.,
2014). Histological evidence indicates that after penetrating the coriaceous cuticle and
epidermis, the white mango scale stylet bundle explores the interior of mango leaf tissue
including vascular bundles by changing its path yet maintaining most of its pathway in the
mesophyll (Rice-Evans et al., 1998).
The female feeds mainly on the mesophyll cells as it pierces them from the path of stylet bundle
without causing their collapse. The exploration pathway of the stylet bundle through the leaf
tissues is mostly intracellular, and the stylet bundle is capable of piercing the lignified cell
walls of vascular bundles (Selman and Dawd, 2012). The feeding nature of scale insects
depends on young mango growing tips and, which can cause distorted foliage. Feeding of the
leaf of mango leaves may cause them to turn yellow and plants may appear water stressed. The
heavily infestations of white mango scale can cause stems and branches to dieback and
unhealthy plants may die (Juarez-Hernández et al., 2014).
The presence of scales on mango fruit caused them to be blemished or distorted, particularly
on the condition of the infestations of white mango scale occurred when fruit were developing.
The small number of white mango scale species induces ornate galls in their host plants. As
mentioned above, the honeydew which released by white mango scale causes the development
of black sooty mold, which can be extremely unattractive and may cause plants to be unsalable.
Black sooty mold which is released by white mango scale can sometimes be removed with
some fungicide applications while it is only recommended after scale insects have been
eradicated (Andrew Manners, 2016).
2.2.7. Damaging and economic impact of white mango scale
Mango trees are subjected to infestation by different pests. Among these pests, White mango
scale insect is considered as the one and the major destructive sap feeding insect pests of mango
trees (El-Zoghby, 2019). White mango scale insects are known to survive on plants completely
submerged at high tide (Harrison, 1916). Many of them are important pests of agriculture
(Miller and Davidson, 2005; Peronti et al., 2001) and may injure or kill plants by depleting
them of their sap, injecting toxins, transmitting viruses or excreting honeydew, which serves
as a medium for sooty moulds (Williams, 1992; Gullan and Martin, 2003).
18
The adaptation of feeding nature of mouth of white mango scale had the form a beak which
was used to pierce the tissues and suck the fluid from the leaf. These types of nature of feeding
of white mango scale mouth was piercing and sucking mouthparts that may damage mango
plants which cause loss of plant vigor due to removal of excessive quantities of sap. When the
infestation level become extreme cases, the leaf of mango become wilting and foliage distortion
(Schoeman, 1992; Miller and Davidson, 2005).
White mango scale infestation cause stunting of vigor of mango tree, damage floral organs and
reduce seed production cause premature leaf-fall by injecting toxins into the plant body using
saliva and then mango tree finally become distortion, proliferation (galls) or necrosis (Duressa,
2018). Some of examples capsid damage on bean leaves and shoots and the stem necrosis on
plants by Helopeltis and other Heteroptera provide entry points for pathogenic fungi and
bacteria (Great head and Pope, 1977).
White mango scale injured mangoes by different mechanism by feeding on the plant sap
through leaves, branches and fruits causing defoliation, drying up of young twigs, poor
blossoming and so affecting the commercial value of fruits and their export potential especially
to late cultivars where it caused conspicuous pink blemishes around the feeding sites of the
scales (Erichsen, 2005).
The insect sucks sap from the plant and secretes honeydew, which deposits on the leaves or
other parts of the plant (Duressa et al., 2018). The honeydew provides conducive substrate
for growth of black sooty mould (Erichsen, 2005). At the beginning of the infestation, only the
leaf base was affected. However, the entire leaf becomes covered with mealy bugs over time
disrupting normal photosynthetic activities and thereby decreasing fruit production (Fitchett
et al., 2016).
White mango scale infestation significantly reduces fruit production and causes substantial
reduction in income to mango and fruit farmers throughout West Africa. Moreover, the
infestation of mango trees by this insect pest significantly reduces the esthetic and shade value
of mango trees in communities (Baker et al., 2009).
The infested areas on leaves turned pale green or yellow and ultimately died. Heavy infestation
of white mango scale could kill leaves, branches and attack of the pest on mango fruit causes
development of conspicuous pink blemishes around its feeding sites and as a result export
potential of the fruits and their commercial value are greatly affected (Joubert et al., 1999;
Hodges and Hamon, 2006; Abo-Shanab, 2012).
19
In the nurseries of mango orchard, the severe infestation white mango scale on the early stage
of mango retards the growth rate of it. Early stage of mango is particularly vulnerable to
excessive leaf loss and death of twigs, during hot dry weather. The heavily infested premature
fruits dropping and the mature fruits became small in size with lacking of juice ((Fitchett et
al, 2016).).
This pest injures the shoots, twigs, leaves, branches and fruits and sucks the plant sap. The
mouth parts of white mango scale were causing, thereafter deformations, and defoliation,
drying up of young twigs, dieback, poor blossoming and death of twigs. The action of the toxic
saliva of this insect pest affecting the commercial value of fruits, and their validity for
exportation potential especially too late cultivars where it causes conspicuous pink blemishes
around the feeding sites of the scales ((Fitchett et al., 2016).).
Attacked fruit is particularly susceptible to this loss in quality as seen by skin blemishes and
hard scales on mango fruit. Contamination by insect faeces, exuviae, and corpses all reduce the
marketability of a crop as do black and sooty moulds growing on the honeydew excreted by
various homopterous bugs. A major problem in the tropics is ‘stickiness’ of cotton lint caused
by honeydew from cotton whitefly, the sticky cotton is difficult to gin and its value is
diminished (Nabil et al., 2012).
2.3. Management of white mango scale
There were management options developed for insect pest controlling in general and for white
mango scale in particular. Managements of white mango scale is genetically by developing
tolerant mango variety from varietal improvement point of view (Dharmendra, et al., 2014)).
Agronomically by practicing appropriate agronomic management and in the field of plant
protection from pest management point of view such as using artificial insecticides; cultural
approach; biological, botanical methods and integrated pest management and the widespread
and rapid establishments of white mango scale in mango orchards or gardens required
immediate changes in integrated pest management program as promising prospect (Sarwar et
al., 2014).
2.3.1. Cultural and agronomical method
Cultural control is one of the management principle in plant protection in order to make the
environment less favorable to pest establishment, growth and development which means
application of optimum amount of fertilizer, pruning, mulching and supplementary irrigation
20
promote plant vigor, tolerance to pest damage, and reduce sap-sucking insect population
growth (Dreistadt, 2014; Dreistadt, 2007).
There were trials with organic and inorganic fertilizer that applied in conventional plantations
of mango management and the infestation increase more in organic farming. White scale
females were more abundant in organic than conventional mango orchards possibly because of
the six monthly applications of fertilizer as indicated by Altieri and who claimed that pests
increased with excessive use of fertilizer especially nitrogen and phosphorus (Bautista-Rosales
et al., 2013).
Plantations of mango under organic farming means, there is no application of input that favored
the presence of natural enemies of white scale like the trash-carrying lacewing Cereaochrysa
sp. (Neuropteran: Chrysopidae), Chilocorussp., Cybocephalus sp (Coleoptera: Coccinelidae)
(Urias-Lopez and Flores, 2005, Isiordia-Aquino et al, 201). The author suggested that organic
farming system increased nutritional quality of plants, and favors reproduction and dispersal
of this insect pest (Nicholls, 2003; Chau et al., 2003).
Pruning is removal of unwanted infested branches from a tree. It is one of the effective in
removing infested plant tissues and reducing populations of scale insect (Kabashima and
Dreistadt, 2014). This types of cultural practice are one of the most important for fruit tree
insect pest management by the improvement of air circulation and reaching of sun light
radiation evenly distribution in order to modify the microclimate of the insect so as to suppress
them. This is one of the most important mechanism to prevent the incidence of insect pest
(Fivaz, 1997).
There are different ways of pruning such as formative pruning which is done in the first years
of the young tree to guide the tree into the desired shape. In the first year, when the trees are
about one meter from the ground, that cap the seedling in order to encourage side branches 3
to 4 well branches. Structural pruning should be done for proper maintenance of the trees. The
height of the trees should be controlled about 3.5 m in height and at this stage, all branches at
knee level should be pruned. Any dead branches and sucker branches should be removed to
allow more sunlight through the canopy to the ground under the tree. There should be done
every year in order to maintain the tree at and develop a suitable canopy density. Post-harvest
pruning was an effective control measure and also helped the penetration of chemical sprays
through the tree canopy (Fitchett et al, 2016).).
21
Different authors suggested that the other possible cultural control measures such as quarantine
new plants and treat before placing them with established plants spot treat with insecticidal
soap if needed taking care to cover all crack cervices and other possible hiding places water
and oil treatments. The application of a garden hose with water in a hard spray and washing off
white scales can be removed following the application of oil wash plants with soapy water
(Tsegaye Babege et al., 2017).
2.3.2. Biological control method
Biological control of insect pest was the utilization of natural enemies. The mechanism reduce
the damage of the crop caused by organisms to tolerable level (Ofgaa Djirata et al., 2016). The
study of white mango scale parasitoids on infested mango in the presence parasitoids was the
common parasitoids represented 40% followed by Encarsia sp., 34% and A. citrinus 26%. Over
40 species of parasitoids and predators, and several fungal pathogens are known to attack the
insect pest of mango (Ben-Dov et al., 2012).
There were commercially available natural occurring parasitoids and predator’s insects. The
parasitoids helped to maintain populations below levels that cause significant damage to the
plants (Hodgson and Martin, 2001). The most known natural enemies used as bio-control
agents in frequency of their application include parasitoids (parasitic wasps and flies) predators
(some insects, spiders and predatory mites) and pathogens (fungi, protozoa, bacteria and virus
(Mills and Daane, 2005).
In the absence of these natural enemies, population explosions of the pest can occur. Aphytis
melinus DeBach and Aphytis lingnanensis Compere (Hymenoptera: Aphelinidae) are the most
common parasitoid species controlling white mango scale populations (DeBach 1974; Watson
et al., 2015).
It was recommended to seek advice from the biological control agent producer prior to
releasing a predator for the first time so that their release was optimized (Mani and
Krishnamoorthy, 2001). If pesticides applied, ensure that a sufficient time period elapses
before releasing beneficial insect’s (Sarwar, 2015). White mango scale was under good
biological control in most other mango producing countries and therefore it was decided to
introduce an exotic biological control agent and try to establish it in different mango producing
areas (Eagling, 2009).
Both the parasite and predators were successfully augmented and released in to mango orchards
and became well established (Daneel, and Dreyer, 1997 and 1998), the predatory thrips
22
Auleurodothrips fasciapennis franklin and the parasitoid (Setegn et al., 2015). White mango
scale was reported as the manageable by predators (Labuschagne, 1996). According to Sayed,
(2012) Cybocephalus sp., Chrysoperla carnea (Stephens), Chilocorus bipustulatus L.). And
predacious mites are predators of white mango scale and Aphytis spp., Aspidiotiphagus citrinus
(Craw) and Encarsia sp. are parasitoids of white mango scale with regard to the collected
numbers of predators (Setegn et al., 2015).
The larvae of the ladybird beetle Chilocorus sp. (Coleoptera: Coccinelidae) infested with white
mango scale and they were found feeding on both male and female white mango scales. When
feeding, the larvae easily destructed coat of the male mango scale and reached it where as they
forcefully pushed their heads inward and partly opened up cover of the female captured and
chewed it (Ikewuchi and Ikewuchi, 2008). In all instances of observations, the presence of the
larvae was associated with colony of white mango scales (Ofgaa Djirata et al., 2016).
In Ethiopia, there were white mango scale (Homoptera: Diaspididae), and its associated natural
enemies and according to the suggestion of him, there were identified and confirmed pecimens
of A. tubercularis, its predators, and its parasitoids were identified via di nucleic acid (DNA)
sequencing. Di nucleic acid sequences of the (COI) gene of all Ethiopian scales sampled were
identical and confirmed as a single haplotype of white mango scale and the author generalized
the predators of white mango scale were recovered. These included two Coccinelidae
(Coleoptera), Rhizobius lopanthe (Blaisdell) and species of Platynaspis and the third
unidentified beetle species from the family Nitidulidae. Di nucleic acid (DNA) sequences of
the parasitoid specimens identified two species of Encarsia, E. lounsburyi Berlese and Paoli
and E. citrina Craw (Hymenoptera: Aphelinidae). These natural enemies were identified for
the first time as resident natural enemies of white mango scale in Ethiopia (Temesgen Fita et
al., 2014; Daneel and Joubert, 2006).
2.3.3. Use of tolerant mango variety
Tolerance plants can be described as the extent to which a plant can support an insect infestation
without loss of vigor, and the reduction of crop yield (Beck, 1965). This does not consider that
tolerance falls within the definition of resistance (Vasugi et al., 2012). The mechanisms of
resistance are divided into three categories namely no preference, antibiosis and tolerance
(Inayatullah and Fargo, 1990). Resistant cultivars are economically feasible and
environmentally safe, and socially acceptable method for controlling various pests and diseases
including insects like white mango scale (Painter, 1951).
23
Host plant resistance to scale insects is likely conferred by an interaction between plant genetic,
physiology, and biochemistry (McClure, 1985; Iyer and Schnell, 2009). The term non-
preference has subsequently been replaced by antixenosis because non-preference refers to the
insect and this is incongruous with the notion of resistance being a property of the plant (Kogan
and Ortman, 1978).
White mango scale infestation on mango was varied among different mango cultivars.
Different literature have different suggestion, Apple mango variety was among the least
infested cultivars (Ofgaa Djirata et al., 2016) on the contrary, Tommy Atkin mango variety has
the capability of tolerance for white mango scale (Camacho and Chong, 2015).The variety of
Alfa and Espada Stahl mango were susceptible compared to Tommy Atkins mango variety to
white mango scale (Rossetto et al., 2006).
2.3.4. Chemical control method
Controlling of insects using chemical method refers to the use of synthetic or organic
compounds capable of killing white mango scale. Various insecticides are registered for control
of white mango scale for mango fruit crop (Stark and Banks, 2003). Crawler are the most
susceptible stage of white mango scale to insecticides. Contact action insecticides including
horticultural oils, become progressively less effective once the scale insects develop their waxy
cover. Insect growth regulators may be effective, provided they are applied when the immature
stages are present (Souaya et al., 2012).
Location of the insect on the plant, growth stage of the plant, and solubility of the insecticide
influence the effectiveness of systemic insecticides applied for control of white mango scales.
Several spray applications at 15–20 day intervals might be necessary for complete management
of a heavy infestation. The toxicity of insecticides to parasitoids and other beneficial insects
should be considered before starting a spray program for scale insects. Since scale is a
quarantine pest in many areas, phytosanitary treatment with gamma irradiation has been
developed as a potential control measure for this scale (Al-Kazafy, 2015).
Synthetic insecticides registered for soft scale management can be broadly categorized into
contact and systemic insecticide. Systemic insecticides include members of organophosphates,
neonicotinoids, tetramic acid derivatives and diamides and which function as contact
insecticides when applied as topical sprays directly on the scale insects. When applied as soil
drench, soil injection, basal trunk spray, trunk injection, granular broadcast and pellet broadcast
24
systemic insecticides were absorbed by plant tissues and translocate to the canopy (Frank,
2012).
Scale insects were difficult to manage using pesticides in the egg and adult phase of life. If
pesticides were to be used to manage scale insects, it is recommended to apply contact products
only when there is a high proportion of crawlers present because crawlers are very susceptible
to many pesticides including oil based products. On the condition of high populations are
present, a systemic product was probably of being required (Andrew Manners, 2016).
The application of the insecticides had to be made just before crawler emergence to ensure the
highest concentration of active ingredients in the plant tissues. Although systemic insecticides
had the benefits of greater flexibility and residual longevity, recent studies suggested that
neonicotinoids should be used carefully because of their potential impact on pollinator health
(Cowles, 2014; Pisa et al., 2015; Johnson and Corn, (2015) and their implication in spider mite
outbreaks (Szczepaniec et al., 2011; Raupp, 2013).
According to Smith et al., (1997) suggestion, petroleum sprays were important for the control
of hard scales in Australia. Application of systemic or growth regulators helped to prevent
population increase. Pre-harvest applications to prevent the scale insects built up during
harvest. High volume (1200L/ha) cover sprays after pruning with mineral oils and methidathion
depending on scale activity. Chloropyrifos, methidathion, Dimethoate 40%EC, (Howard,
1989), Diver and CAPL oils have been found successful in reducing the population of white
mango scale (Abo-Shanab, 2012; Abhilash, and Singh, 2009).
According to Andrew Manners,2016 suggestion in his recommendation, active ingredients
registered against scale insects relevant to Australian mango nurseries included Carbaryl,
Chloropyrifos, Diazinon, Dimethoate, Methylation, Imidaclopride, Pyriproxyfen, Buprofezin,
Paraffinic oil and Sulfer. The studies of Gashawbeza Ayalew et al., (2015) reported to the
Move to be effective pesticides against integrated white mango scale.
According to Ofgaa Djirata et al., (2016) Folimat 500SL was found to be the most effective
of the three insecticides and the best period for application of insecticide for the control of
white mango scale is from April to June when white mango scale crawlers are more abundant
in western Ethiopia. White mango scale introduced to Ethiopia recently from its origin and
related natural enemies should be conducted for the designing and implementation of classical
biological control. The population density of white mango scale was above the economic injury
25
level so that there should be the implementation of insecticides and Folmit 500SL was found
to be the most effective insecticides against white mango scale.
2.3.5. Integrated white mango scale practice
Proper and constant scouting and monitoring of pest populations is another important (IPM)
strategy towards management of white mango scale pests. Monitoring is the process of
searching, and watching regularly for the appearance of white scale pests to help in early
detection and control before causing injuries. White scale should be monitored fortnightly from
flushing stage after mango harvesting (here, check on leaves) and when fruits are 1.5-2 cm
across (here, check for both fruits and leaves) (Duressa, 2018).
It minimizes pest damage with minimal disturbance to the natural balance of the agro-
ecosystem and minimal risk to human health. It does this by decreasing the net chemical
pesticide inputs to agriculture. This eventually minimizes dependence on chemical pest control
(Goodwin, 2000).
Integrated pest management falls between conventional and organic agriculture. The
introduction of integrated pest management presents ecologically feasible, socially acceptable
and economically effective alternative to conventional agriculture by significantly lowering the
costs of chemical pesticide application as well as an alternative to organic agriculture
(Vayssières et al., 2010).Controlling white mango scale using individual management
strategies of pest management principle is impossible so that white mango scale has to be
applied that would consist of a combination of pesticides, tolerant mango variety, biological
control agents, botanical, cultural practices and chemical together is the best option (Meyerdirk,
2002).
White mango scale management strategies were often the exception rather than the norm
because of their higher labor demands and this was generally the reason why they practiced on
a small scale. In many cases, it demonstrated not to substantially affect productivity (Kumari,
et al., 2014). According to Ofgaa Djirata, et al., (2016) integrated approaches to managing
white mango scale management was effective in Ethiopia. The study was revealed that cultural
practices such as cyclic pruning and consistent scouting for white mango scale infestation and
removal of infested parts are essential management practices (Wageningen, et al., 1999).
It can be enhanced by proper canopy management practices, especially for commercial fruit
cultivation, the natural form and shape of fruit trees are to be modified through the practice of
pruning to achieve the targeted yield by scientific approach. The allowance of a plant to
26
develop naturally since unwanted portions may develop at the expense of those which are
essential. Appropriate pruning practices keep the plant in such shape and condition as to yield
fruits of desired quality.
CHAPTER 3.MATERIALS AND METHODS
3.1. Assessment of White Mango Scale
3.1.1. Description of the survey area
The survey was conducted at Wogelsa, Sebatamit and Gombat rural kebele in 2020 cropping
season located in Bahir Dar Zuria District in Amhara region, North Western Ethiopia from
September 2020 to September 2021 (Figure 3.1). The District was situated at 576 km
Northwest of Addis Ababa, the capital city of Ethiopia.
Bahir Dar Zuria District is geographically located at 11° 14' 60.00" N North latitudes and 37°
09' 60.00 East longitudes. The maximum rainfall of the study area was 430mm per year while
the minimum rainfall was 380mm per year. The maximum temperature of the study area was
27C0 while the minimum temperature was 10.7C0.
The average elevation is about 1801meters above sea level. The land scape is flat with some
small hills to the east and west (BoARD, 2020). The area consist three ecology types. The
farming practices of the study area is cultivated major crops like Finger millet, maize and tef;
and from fruit crops mango, orange, Guava and banana were the major once.
27
Figure. 3. Meteorological data Source: Bahir Dar meteorology service agency, 2021
0
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30
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28
Figure 3.1. Location map of the study site
3.1.2. Study design and sampling size
The perception of the growers about the insect, status of mango tree, white mango scale,
alternative host range, seedling source, grower’s management practice was carried out from
September 1, 2020 to August 15, 2021.For the survey research work, about thirty-three mango
orchards or growers in Wogelsa, Sebatamit and Gombat were selected for the survey work with
the help of (Yemane taro, 1967). The sample areas of the survey sites were selected with the
help of the District administration based on mango growing potentiality.
The focus of survey was the infestation of white mango scale as a hot spot area. The selected
mango growers had minimum of ten mango tree in their mango orchards. The total area
coverage of mango tree in hectares nine, eleven and fifteen respectively for Wogelsa, Sebatamit
and Gombat rural Kebele. Farmers participated in the growing of mango were about 256 in
Wogelsa,244 in Sebatamit and about 229 in Gombat.
29
3.1.3. Procedures of survey work
3.1.3.1. Procedures of survey of grower’s perception
The survey was started from Wogelsa rural Kebele in Bahirdar Zuria District, West Gojjam
administrative Zone. In the first step growers in Wogelsa rural kebele was interviewed with the
help of close, and open ended standard structural quatinaire. That means in the close ended
questions only from us for them whereas in the open ended respondent can give from them for
us. The growers were asked in Amharic. The interviewing of growers was carried out in the
face to face approach. The selected mango Growers for interview lived at series of spots within
intervals of 5 to 10 kilometers land distance considered their village in each household. The
survey continued to Sebatamit, and finally to Gombat. Growers gave response based on their
observation and experience for the prepared questions (Appendix Table. 1).
3.1.3.1. Procedures host plant identification
In the identification of host of white mango scale, the activity was carried out in mango
orchards. In the mango orchard that means Mango, Guava, Orange, Papaya, Banana, and
Avocado and, forest plants like eucalyptus, and Wanza farms potential areas, there was
diagnosed activity. In this work, four sample leaves per selected vascular plant cut from four
cardinal compass directions with 10Km distance interval in each farm. The collected sample
leaves in each vascular plants were collected, pressed and mounted, and taken to Bahir Dar
University College of Agriculture and Environmental sciences, Department of Plant sciences
plant protection laboratory (Appendix Figure. 2).
3.1.3.2. Procedures of infestation survey
In the assessment of prevalence, incidence, and severity, the survey was carried out with the
similar procedure of the above, ten mango leaves (3 from upper, 3 from center and 4 from
lower canopies) were plucked from every mango tree selected from about 50 central position
within each farm. Collecting of sampling continued as far as there were mango farms and
infestation of the insect pest along with mango farm. Sampling was terminated when it was
confirmed that there was achieving the number, over land distance of about 5 Km from the spot
of the last sampling. However, considering a report on quick spread of the pest to the west
(Temesgen Fita, 2014).
3.1.3.3 Procedure of mango variety selection
30
For the surveying of mango variety, varieties were characterized with the help of phenotypic
features of mango tree. That means Morphological characters were the first step that should be
done before more profound biochemical or molecular studies were carried out (Hoogendijk
and Williams, 2001). In this regard, in mango cultivars character, mango leafs were used in the
identification of the variety with the help of morphological features like precocious, dwarfness,
regular and prolific in bearing, early flowering and fruit setting, canopy architecture, growing
habit, attractive fruit color and size of leaf (Litz, 2009; Davis et al, 2012).
3.2. Field Experiment
3.2.1. Description of the experimental site
Experiment study was conducted at Zenzelima located in Bahir Dar District, Amhara Region
North Western, and Ethiopia during 2020/2021 cropping calendar in private mango orchards.
Zenzelima lied between the 11°37'8.86"N latitude and 37°27'38.04"E longitude, and the mean
altitude 1820 meters above sea level. Zenzelima situated at the out skirt of Bahir Dar city about
10km.The minimum temperature of the area is 10.7C0 while the maximum temperature was 25
C0.The maximum rainfall of the area was 380 mm while the minimum rainfall was 300mm.The
Agro-ecological zone classified as being too cool to sub-moist mid-highlands. The kebele has
this kebele consists of the three villages Sesaberet, Gedro and Michael (Figure 3.2).
Figure 3.2. Location of the experimental site
3.2.2. Insecticides and experimental design
There were four tested insecticides. These were Nimbecidence (3%) EC, Folmit (40%) EC,
Karate (5%) EC, and untreated check. These insecticides had their own features namely
31
Nimbecidence (3%) EC is a neem-oil-based botanical insecticide, and occurs naturally in neem.
This insecticides is foliarly applicable with multipurpose namely antifeedant, repellent,
ovipositional deterrent, antifeedant, insect growth regulator and sterility (Patil, 2009). The
insecticide was important for pests of Hemiptera diaspidea family. The manufacturer
recommendation of this insecticide per hectare ratio was 3 liters of Nimbecidence (3%) EC
with the volume of 300-liter water (Maha, 2009).
Folmit (40%) EC is the systematic insecticides chemical group organ phosphorus. It is suitable
for the controlling of sucking types of insects. The insecticide penetrates the tissue of the plant,
and that becomes toxic for sucking types of insect. The insecticide was recommended 2 liters
folmit (40%) EC per hectare with the volume of water 500-liter ratio (Walthall and Stark,
1997).
Karate (5%) EC was a group three emulsifiable concentrate contact. This is stomach insecticide
for the control of various insects. This insecticide is broad spectrum synthetic parathyroid
insecticide for the control of insect pests (Smiley and Yan, 2011). It was effective product, and
had the capability of controlling several crop pests in one spray with knockout properties.
Karate EC 5% was formulated with the active ingredient lambda cyhalothrin its novel granular
formulation-pours like a liquid. Karate (5%) EC was recommended with quantity of volume of
2 litters per insecticides per hectare ratio of this insecticide with the amount of water 300L
(MoA, 2016).
The variety used for chemical evaluation was Tommy mango. The variety was selected with
the help of morphological and physiological features. That means Tommy mango variety has
scatred canopy, less melting of the organic compounds. That features of mango tree make it
less susiptable. The selected mango trees were uniform in size, similar in age about four years
old (Table, 3.1). The experimental study of chemical screening was single factor experiment
so that Simple Randomized Complete Block Design (RCBD) with three replications was used
for the evaluation.
3.2.3. Procedure of the study
3.2.3.1. Procedure of the experimental study
Tommy mango tree was blocked into three blocks considering as a plot. Each of mango tree
was marked as plot. Before the spraying of the insecticides: The insect occurrence was checked
with the help of hand lense in economical threshold level, the flowering of mango takes into
consider relation to abortion so that the selected mango trees were treated before the flower
32
induction, and spray was taken place during active stage of mango flowering stage by
considering abortion effect (Williams et al., 2002).
The collection of recording data of white mango scale was carried out randomly from four
sample 20 cm twing of mango tree. The 20 cm length twing were collected from four directions
with the totality of 16 sample twing per replication and 48 sample twing from the three
replication in 12 treatments. While recording the insect data, the death and live insects was
identified using hand lenses (Gashawbeza Ayalew et al., 2014 and Ofgaa Djirata et al.,
2017).
Before the application of the insecticides, mean number of white mango scale population per
plot 4 twing which had the length of 20 cm prior to treatment application four 20 cm sample
twing plunked by measuring using pocket meters from one mango tree with the totality of 48
mango twing was plucked from each mango tree, and collected in bags as a base line data. The
collected base insect data from each mango tree was counted, and recorded in the data recording
sheet of mango tree. Then the calibration of the insecticides as well as volume of water per
hectare was calculated per hectare ratio. The amount of insecticides was measured siring and
needle. The amount of insecticide as well as water volume rated according to the leveling of
the manufacturer. The amount of insecticides was measured based on four hundred mango tree
per hectare ratio.
The amount of insecticides, and volume of water was calculated per mango as treatment. About
0.0075L of Nimbecidine EC 40% with 1.5 L,0.0075L Karate EC 3% with 0.75L water, and
0.005L Folmit EC 5% with 1.25L water. The rated insecticides of each plot was mix in the
knap sack for each of mango tree turn by turn finally spraying of the insecticides implemented
from starting from the top section of mango tree with the help of ladders.
Spraying of the first round insecticides application was implemented in December 15/2021
before 3:00 Ethiopian local time for each mango tree, while spraying the direction of the wind
was considered using personal techniques by wearing gloves. One week after the first round
spraying application, mean number of insects from post treatment was used to assess efficacy
of the suggested management option four 20cm sample mango twigs 48 twigs from each mango
tree was cut, and which was inserted into the bags paralally in their plots according to their
level. Then the second round spraying application was applied one week later from the first
round spraying application then the application of the second phase considered interval of
33
application two weeks during December 22/2020 before 3:00 Ethiopian local time using
motorized knapsack sprayer.
Spraying of the second round application of the insecticides, mean number of white mango
scale population per plot 4 twing which had the length of 20 cm prior to treatment application
the plucked 20cm mango twigs with the totality of 48 mango twigs inserted in posta and dead
and live insects collected, identified recorded and counted with the help of hand lenses.
Other mango variety in the middle of the experimental site was considered as protector of drift
problem as well as insect transportation. The untreated checks were maintained
for comparison purposes. The untreated control mango tree was wetted two times with water
to avoid moisture difference between mango trees. All the non-experimental variables were
kept in the same way for all mango tree during the experimental period.
3.2.3.2. Procedures of phenology study mango tree
Mango trees were selected in the private mango orchards. The selected mango variety were
marked.The sample scoring data were collected one time from representative farmer’s mango
orchards. In the first round, 20cm length sample mango twigs were plucked from four compass
directions in the first of the activity. These cuttings were put into posta and finally counting of
the numbers of white mango scale was with the help of handlense. The recording of the number
of white mango scale number was carried out randomly from four sample 4 mango leaves. The
counting of the insect continued in similar way in each phase of mango tree (Gashawbeza
Ayalew et al., 2014 and Ofgaa Djirata et al., 2017).
3.2.3.3. Procedures of study of variety selection
In the selection of mango variety, The selected mango trees were designed and marked.
Then in each mango tree, the scoring of insect’s severity has been determined using the scoring
techniques (Williams et al., 2009). According to the nature of the study. The scoring of white
mango scale on the leaf of mango tree in the phenological nature of mango tree, growth phase,
spacing and variety selection were determined with the help of scoring techniques from 0 to
5 scale using different ranges as follow: Free= <5% (0) of the panicle destroyed, minimal
damage = 5 to 24% (1-2%) of the panicle destroyed, Moderate = 25 to 50% (2-4%) damage,
Severe =51 to 70% (4-5%) damage and Very severe = 71 to 100% (5) damage (Williams et al.,
2009 ) rating and categorizing white mango scale in different life cycle of white mango scale
namely eggs, nymph and adult.
34
3.3. Data collection
Response of the growers (%): About white mango scale infestation level, and the status of
mango tree plantation measured in each kebele in percent form.
Awarmess level of white mango scale (%): The response of growers about their knowledge of
white mango scale counted and determined in the percent form.
Distribution (%): It was determined by calculation the number of study unit kebele that
occurred or not white mango scale, and measured in the percent form.
Incidence (%): It was determined by the number of plant infested from the total observed
plants in the percent form.
Severity (%): It was collected by scoring using scoring ranges from (1-5) in the infested plant
parts.
Insect colonies (N): This was counted and recorded of white mango scale by counting out
from the sample 20 cm length twing of mango tree.
Eggs of white mango scale (N): It was determined by counting the scale of white mango on
the leaf surface of mango tree.
Nymphs of white mango scale (N): It was counted on the leaf of mango tree with the help of
hand lense.
Adults of white mango scale (N): Adult insect of white mango scale was measured by
counting from the surface of tree.
Severity level of white mango scale (%): It was recorded by scoring with the scoring gade (1-
5) the damaging leaf surface of mango tree with the help of hand lense.
3.3. Statistical data analysis
3.3.1. Analysis of survey
3.1.1.1. Analysis of infestation of white mango scale
The percent of prevalence, incidence and severity of white mango scale were determined as
suggested by earlier researchers. The frequency of white mango scale occurrence at each
locality (mango farm) was calculated by the use of equation adopted from Kataria and Kumar
(2012). This value was used to define severity index from which severity status at each farm
was determined. Abundance at each the distribution of white mango scale refers to the total
number of district assessed farms divided by the total number of samples kebele and it is
expressed by the following formula:
Frequencies of WMS prevalence (%) =Number of WMS recorded per study site x100
35
Total number of WMS recorded from surveyed
The frequency of white mango scale incidence expresses as the percentage of the number of
total samples relation to total sample occurrence. It is obtained from the relationship between
the number of samples containing the farms and the total number of samples in the case of the
total white mango scale sampled.
Percentage of WMS incidence (%) = Number of infested mango tree plants X100
Total number of observed mango plants
The frequency of white mango scale severity was expressed as the percentage of the number
of total samples relation to total sample plant leaf scored. It is obtained from the relationship
between the number of samples containing the farms and the total number of samples in the
case of the total white mango scale sampled.
Severity (%) =Sum of total grade point (1-5infestation grade) of the infested plantx100
Total number of infested plants observed
3.3.1.2. Analysis of grower’s perception
Demography characteristics, plantation status of mango, white mango scale status and all farm
assessment agronomic data namely pruning, irrigation, mulching and others that were collected
from the sample farms survey was managed, and analyzed using Microsoft excels software
version 2010, and the Statistical Program for Social Sciences (SPSS) software version 2016,
and (STATA) considering the aforementioned suggestion. Descriptive statistics (percentage)
were used for computing data on distribution and Constance of white mango scale was carried
out.
Appropriate statistical method, T test and chi square(X2) was used for computing the
distribution, and frequency of white mango scale occurrence in sex determination and avoiding
of the pruning of mango tree recorded from sampled mango orchards of the study area
Significant differences between means were separated by Turkey’s honestly significant
difference (THSD) test at 95% confidence interval level.
3.3.1.3. Analysis of host plant
For confirmation of the white mango scale, about 10 leaves, 5 twigs and 5 fruits which present
at different heights were cut from every vascular plant found within the proximity of infested
mango trees by measuring using pocket meters. These Cutting plant leaf and twing was checked
by hand lens for the presence/absence of white mango scale. They are host or not for white
mango scale with the help of hand lenses. Mango, Guava, Orange, Papaya, Banana, Avocado
and, forest plants like eucalyptus, and Wanza farms potential areas (Appendix Figure.1).The
36
procedures, and keys of the books related to white mango scale insect pests, and other
arthropods by different authors (Hag strum, et al., 2013;Hagstrum and Subramanian, 2006;
Rees, 2004, 2007) were used for identification this insect.
Identification of white mango scale hosts plants was done using sign and symptom of white
mango scale such as white scale or nest on different vascular plants among others, using keys,
and morphological characters of the aforementioned books. Then after, sample leaves were
sorted according to the crop family and counted for each sub sample leave different.
3.3.4. Experimental data analysis
The mean number of white mango scale, and the mean severity of each white mango scale
colonies were subjected to one-way analysis of variance to compute mean severity, and mean
number of white mango scale in each factors. Moreover, the status of each pest was determined
using distribution, and frequency of occurrence of the pests as suggested by the aforementioned
scholars. Significant differences between means were separated by least significant difference
(LSD) test at 95% confidence interval level (Gomez and Gomez, 1984 and SAS Institute,
2009). Percent reduction in white mango scale population over control was worked out after
each treatment using Henderson and Tilton (1955) formula of mortality correction.
Where n=white mango scale population
T= treated, and Co=control
37
CHAPTER 4. RESULTS AND DISCUSSIONS
4.1. Survey of White Mango Scale
4.1.1. Demographic characteristics of the respondents
From the total number of participants considered for the study, the response rate obtained was
100 % .From the total respondent,72.8 % was male while 27.2 % of the growers were female.
About 17.17 % of the respondents were below 30 years while 19.9 % of them were ranging
from 30-40 years, and 12.23 % of them were from 41-50 years while 13.5 % of them were
from 51-60 years and 35.6 % of them were over 60 years old. About 34.73 % of them had
less than 5 families while 37.1% of them had from 5-10 family, and about 28.26 % of them had
greater than 10 family members. About 32.5 % of them were illiterate while 32.0 % were
in primary school, and about 19.05 % of them were secondary school, and about 16.45 % of
them were University and College level (Table 4.1).The study indicated the variability of
educational sex, education, family size as well as age of the respondent.
Table 4.1. Demographic characteristics of the respondents in Bahir Dar Zuria District from
2020/2021 cropping season
Proportions of the respondent (%)
Variable Wogelsa Sebatamit Gombat Total
Sex
Female 29.3 25.5 26.8 27.2
Male 70.7 74.5 73.2 72.8
Age categories
Below 30 31.1 11.2 9.2 17.17
31-40 29.2 19.3 11.2 19.9
41-50 13.2 13.2 10.3 12.23
51-60 10.3 10.1 20.1 13.5
Above 60 16.2 46.2 49.2 37.2
Sum
Family size
<5 44.5 30.5 29.2 34.73
5-10 35.4 34.4 41.4 37.1
>10 20.1 35.1 29.4 28.26
Education status
Illiterate 34.4 33.3 30.4 32.5
Primary school 35.1 30.3 30.4 32.0
Secondary school 13.2 16.2 27.0 19.05
University/college 17.3 20.2 12.2 16.45
38
4.1.2. Mango tree plantation status
About 13.06 % growers were increase while 62.08 % of them were decreasing, and 24.76 %
of them were no change of mango tree number from the previous. About 28.8 % of them were
two years while 45.03 % of the growers from 3-5 years, and 28.17 % they were before 6 years.
About 22.23 % of the producers had < than 15 mango tree while 34.36 % of them had ranging
from 16-20 numbers of mango tree, and 16.86 % of them possessed from 21-40 numbers of
mango tree and 15.83 % of the producers had > 41 numbers of mango trees in their orchards.
(Table, 4.2).
The study perceived that as this insect infestation pressure on mango tree. The infestation
pressure of the insect is directly connected with the introduction of white mango scale. Studies
supported that white Mango Scale was a sucking insect that poses severe threat to mango
plantations mango growing countries (Labuschagne et al., 1996; Pena et al., 1998 and Juárez-
Hernández et al., 2014).
Table 4.2. Mango growing experience and the status of mango plantation in Bahir Dar Zuria
District from 2020/2021 cropping season
4.1.3. White mango scale infestation and their perception
22.8 % growers were unfamiliar of this insect pest problem while 77.2% of the producers were
informed about white mango scale. About 63.63 % of them were increase while 15.85 % of the
respondents decrease, and 16.99 % of them were had no clue (Table, 4.3).
Proportion of the respondent (%) Variables Wogelsa Sebatamit Gombat Total
Number of mango
tree
<15 20.2 29.4 17.1 22.23
16-20 43.4 40.4 19.3 34.36
21-40 22.0 13.1 22.4 16.86
>41 14.2 12.0 21.3 15.83
Status of plantation
Increasing 9.1 9.7 20.4 13.06
Decreasing 63.5 72.7 52.3 62.83
No change 27.4 16.7 30.2 24.76
Time of decrease
<2 years 35.4 29.7 21.3 28.80
3-5 years 38.4 48.3 48.4 45.03
> 6 years 26.2 22.0 30.3 26.17
39
About the awareness of white mango scale in terms of gender, they had not significant different
(F 0.226, P> 0.05%). This might due to less attention giving for the occurrence and impacts of
white mango scale.
Table 4.3. White mango scale infestation and Perception of the respondent about the
infestation in Bahir Dar Zuria District during 2020/2021 cropping calendar
Proportion of the respondent (%)
Variable Wogelsa Sebatamit Gombat Total
Awareness
Yes
21.3
22.9
24.3
22.8
No 78.7 77.1 75.7 77.2
Infestation status
Increasing 67.2 56.3 67.4 63.63
Decreasing 15.6 18.2 13.8 15.86
No change 17.2 25.5 18.8 20.5
Gender Yes % X2 (P-value)
Female 22 43.13
Male 29 56.86 0.226(0.635)ns
4.1.4. Growers response about pruning of mango tree
From the interviewed growers, 84.7 % of mango growers did not prune their mango trees while
15.7 % of them pruned their mango trees. About 15 % the respondents was used as mulched
materials while 9% of them were used for fencing. About 4 % of them were avoided by buried
while 2 ሰ% of them avoided by burned (Table, 4.4).
Concerning to the avoiding mechanisms of pruned mango tree, there were no significant
difference among the avoiding mechanisms of pruned branches (F14.08, ns, P>.05) when
compared each other (Figure 3.3). The study indicated that canopy management depends on
the nature and growth pattern of plant number of plants per hectare and pruning techniques
(Temesgen Fita, 2014).
The results of the study revealed as mango growers lack of comprehension of the usefulness of
pruning as a cultural practice in the management of white mango scale. According to the
literature, pruning allowed air, sunlight, reducing pests, and improving fruit color (Bally,
2006). Also pruning of the tree increases output, minimizes costs of production, improves fruit
quality both size and color, eliminates insect pest and disease incidence, sustains productivity,
and extends the productive age of a fruit tree. The fruit size of Tommy Atkins and Sensation
mango cultivars for example was enhanced by pruning after fruit set (Fivaz et al., 1997).
40
Most growers were unfamiliar only with dumping technique even if they had sought to manage
white mango scale culturally. Similar studies have indicated that distributing vegetative
elements, and other plant parts as well as any material beneficial in destroying white mango
scale habitat (Williams et al., 2009).
Table 4.4. Response of producers about pruning practice of mango tree in Bahir Dar Zuria
District during 2020/2021 cropping season
Proportion of the respondent (%)
Pruning Wogelsa Sebatamit Gombat Total
No 69.9 40.2 13.3 84.7
Yes 30.7 39.5 19.9 15.3
Disposing
Response
Percent
X2 (p-value)
Burning 2 7.0
Buried 4 23.0
14.708ns
Mulching 15 50.0
Fencing 9 30.0
Ns=Non-significant difference.
Figure 3.3. The avoiding mechanism of producers after pruning the infected branch
4.1.5. Agronomic practice of mango tree
From the assessed mango farms, 37.73% was mulched while 62.27 % of the tree was not
mulched. About 47.97 % of the farm had not irrigated while 52.03 % of the farm did non-
irrigated. About 40.2 % of the farm did not use input for mango, and 59.08 % of them were
used input. About 31.93 % of them were used conventional farming practice while about 68.06
% of them were used organic farm (Table, 4.5).
The study perceived that white mango scale insect incidence had relationship with the cultural
practice of mango tree. When mango tree was practiced in conventional and cultural, the
pressure of white mango scale varied accordingly. Literatures supported that study as excessive
41
use of chemical, insecticides, and traditional farms influenced mango production and
productivity. Improper agricultural practices encourage the incidence of insect pests
(Salahuddin et al., 2015; El Llano et al., 2010).
Table 4.5. Cultural practice of mango tree in Bahir Dar Zuria District from 2020/201
Cropping season
Proportion of the respondent (%)
Variable Wogelsa Sebatamit Gombat Total
Mulching
Yes 50.1 42.6 20.5 37.73
No 49.9 57.4 79.5 62.27
Irrigation
Yes 42.8 55.6 45.5 47.97
No 57.2 44.4 54.5 52.03
Fertilization
Yes 55.7 39.5 25.4 40.2
No 44.3 60.5 74.6 59.8
Farming system
Organic 9.6 70.4 15.8 31.93
Inorganic 90.4 29.6 84.2 68.06
4.1.6. Growers mango seedling source
About 46.43 % of the growers got their mango seedling from government grafting nurseries
while 24.96 % of the respondent were used their own mango seedlings, and 28.61 % they got
their seedling from a private multiplication site. About 30.9 % of mango tree were improved
mango variety while 34.3 % the trees were indigenous mango trees, and 34.08 % of mango
trees were consolidated both local and improved (Table, 4.6). This indicated government
multiplication site is the main source of mango seedlings. White mango scale spreaded by the
transfer of infested plant material and the importation of fruit, as according various research
findings (Suit, 2006).
This study indicated that the fruit crops grown was less in terms of quality. Literatures
supported that Mango trees which grown in most parts of Ethiopia developed from seedlings,
and are inferior in terms of in productivity in terms of fruit quality. Considering this, the inferior
quality trait of mango, improved mango varieties named Kent, Keitt, Tommy Atkins and apple
were introduced from Israel in 1983 and are being commercially produced by the Upper Awash
Agro industry enterprise and distributed in to different parts of the country (Mohammed Dawd,
et al., 2012; Temesgen Fita, 2014).
42
Table 4.6. Growers mango seedling source in Bahir Dar Zuria District during
2020/2021Cropping season
4.1.7. Controlling practice of white mango scale
About 91.5% was implemented integrated white mango scale controlling practice while 93.7%
of the growers were applied cultural practice, and 34.2% of them were applied botanical insect
pest management, and 24.2% of them were used chemical insect pest management practice.
About 41.5% of the respondent were uncertain about the effectiveness of the effectiveness of
practice while 30.3% of them were not successful in their controlling practice, and 12.2% of
the growers were succeed to some extent in their controlling practice, and the rest 9.1% of the
growers were successful in their controlling techniques (Table, 4.7).
This implied as growers were not satisfied for what they have practiced for their management
option of white mango scale. The management of white mango scale was influenced by the
nature of the insect itself.
Table 4.7. Growers controlling practice of white mango scale infestation in Bahir Dar Zuria
District during 2020/2021 cropping season
Proportions of the respondent (%)
Variables Wogelsa Sebatamit Gombat Total
Management
Cultural 33.0 33.0 33.0 33.0
Botanical 16.9 17.8 20.3 18.33
Chemical 17.8 16.9 14.8 16.5
IPM 32.3 32.3 31.9 32.17
Effectiveness
Yes 19.0 19.0 19.0 19.0
Proportion of the respondent (%)
Variables Wogelsa Sebatamit Gombat Total
Seedling sources
Government nursery 48.6 49.4 41.3 46.43
Own seed/seedlings 21.5 22.8 30.6 24.96
Privet multiplication 29.9 27.8 28.1 28.61
Variety
Local 34.2 29.9 28.6 30.9
Improved 32.8 31.0 39.1 34.3
Both mango variety 33.0 39.1 32.3 34.8
43
To some
extent
12.8 23.9 19.9 18.86
Not at all 27.2 24.1 29.0 26.77
Not aware 41.0 33.0 32.1 35.37
4.2. Assessment of White Mango Scale in mango orchards
4.2.1. Incidence, prevalence and severity
The distribution of white mango scale was 100% while the occurrence of white mango scale
were 100%, and the severity of white mango scale were 80.76% (Table, 4.8).
The findings of this study indicated that white mango scale had been influenced by several
factors. Study reports indicated as White mango scale pest spread so fast, and is expected to be
present throughout the year with high incidences at flowering and fruit maturation stages. In
Ethiopia. The incidence of white mango scale was reported to vary between 40 and 100%
(Duressa, 2018). Weather is an important factor determines white mango scale distribution,
abundance and their dominance. According to Dharmendra et al., (2014) favorable weather
condition for high pest infestation ranges between 24-35°C and relative humidity 70-95% in
both mango orchards (Salem et al.,2015).
Table 4.8. Infestation status of white mango scale in Bahir Dar Zuria District during
2020/2021 Cropping calander
Proportions of the respondent (%)
Infestation Wogelsa Sebatamit Gombat Total
Prevalence 100.0 100.0 100.0 100.0
Incidence 100.0 100.0 100.0 100.0
Severity 74.5 88.1 79.7.0 80.78
4.2.2. Mango variety and white mango scale infestation
About 20.26 % of mango tree were planted with other crops while 79.73 % of mango tree were
planted without other crops. About 37.5 % of mango were planted in triangular planting
technique, while 39.9 % of mango farm were planted in rectangular planting ways, and 22.8%
of mango farm planted in square planting method (Table. 4.9). About 33% of the tree were
local while 30.5% of the variety were Tommy, and 29.7% of the variety adopted were Kent,
and 28.4 % of the variety were Apple, and 30.2%% of the mango variety were Keitt mango
variety (Appendix Table, 3).
44
The result of the study indicated that white mango scale incidence had direct relation with the
planting system, and pattern of mango tree. According to studies, the most significant element
in attaining a reasonable return by controlling the incidence of insect was the regular planting
pattern of mango trees (Verheij, 2006). This types of practice become the cause for competition
and stress for mango tree. Such kinds of agronomic practice make the crop succulent for insect
pests. According to studies, the most significant element in attaining a reasonable return by
controlling the incidence of insect was the regular planting pattern of mango trees (Verheij,
2006).
The results of the study indicated that grower is adopted all mango varieties considering their
yield quantity and quality and adaptability, but not, gave focused for tolerant level of the insect
pests.Literatures supported that improved mango cultivars named Kent, Keitt, Tommy Atkins,
and apple mango varieties were brought from Israel in 1983 and were commercially cultivated
by the Upper Awash Agro Industry Enterprise and distributed throughout the country because
of their high yield and ecological adaptability (Mohammed Dawd, et al.,2012; Temesgen Fita,
2014).Mango trees are often irregular in their cropping habit with no clear pattern across
different years and place due to the variability of mango ecological adaptation and genotypes
of mango tree.
Table 4.9. Cropping system of mango tree in Bahir Dar Zuria District from
2020/2021cropping season
Proportions of the respondents (%)
Variables Wogelsa Sebatamit Gombat Total
Cropping system
Sole crop 34.7 14.3 11.8 20.26
Intercrop 65.3 85.7 88.2 79.73
Cropping pattern
Rectangulate 52.5 39.2 20.7 37.5
Triangulate 18.4 40.4 60.8 39.9
Square 29.1 20.4 18.5 22.8
Variety
Local 33.0 33.0 33.0 33.0
Apple 28.3 32.6 30.6 30.5
Kent 30.9 28.6 29.6 29.7
Keitt 28.5 30.6 26.2 28.4
Tommy 30.1 30.4 30.1 30.2
45
4.2.3. Alternative host identification
From the assessed vascular plants farm about the occurrence of White mango scale in the
survey mango orchards, there were fruit and forest tree plants infested (Appendix Figure. 2).
From the selected vascular plants in the survey, Mangifera indica and Guava from tropical fruit
crops while lime and orange from citrus family and Eucalyptus from field forest tree plants
were infested by white mango scale (Figure, 3.4). Each of the vascular plants in the field of
crops had been identified as host plant of white mango scale (Table 4.10).
The result of the study indicated that white mango scale infested other vascular plants other
than mango tree with relation to its polyphagous feeding nature. Studies other than Ethiopia
reports supported as polyphagous species were the most prevalent insect, and they were more
become major pests when introduced to new areas because of their wide host range facilitates
their establishment (Kosztarab, 1996) leading to a shortage of natural enemies to control their
populations (Stocks, 2013).
However, Studies reported as mango was the only host of white mango scale in Ethiopia (Ofgaa
Digitera et al, 2017). According to the explanation of him abundance of mango plantation may
be one possible reason to have been the only colonized plant by white mango scale in western
Ethiopia.
The author stated described that host plant abundance is known to positively influence host
plant use, in both specialist and generalist herbivorous insects. The rate at which a dispersing
or foraging insect finds a host plant can be limited by abundance of the plant. It is obvious that
western Ethiopia is one of the most known mango producing regions in the country (Ethiopian
Ministry of Agriculture and Rural Development, 2009; Takele Honja, 2014).
Table 4.10. Alternative hosts of white mango scale in Bahir Dar Zuria District from
2020/2021cropping season
Botanical Name Common Name White Mango Scale
Psidium guajava Guava R
Key lime Lemon R
Eucalyptus globulus Blugum R
Mangifera indica Mango R
Citrus sinensis Orange R
Carica papaya Papaya Nr
Musa spp. Banana Nr
Persea Americana Mill Avocado Nr
Cordia Africana Wanza Nr
Nr = non recorded, R= recorded
46
4.3. Field Experiment
4.3.1. Severity of white mango scale on each phenology of mango tree
The presence of white mango scales populations ranging from 61 (15.1%) to 14 (4.4%) per
four leaves per tree was significant different (F 35.09=992.07, P<.05%) when compared to the
other parameters (Appendix Table. 3).
The number of eggs, nymphs and adult colonies respectively on phenological cycles of mango
was about 76.0,61.4 and 55.4 for fruit set while 67.5,40.3 and 37.4 for young shoot, and
54.3,29.2 and 37.4 for inflorcence,46.3,20.7 and 19.4 for fruit development while 44.7,15.8
and 14.5 sensenced;21.2,13.4 and 13.2 for maturity, and 16.8,9.9 and 12.2 for bud
development, and 15.0,8.4 and 5.33 for old shoot of mango tree respectively (Table. 4.11).
This explains that white mango scale infests throughout entire phenological cycle of mango
tree (Rajan, et al., 2011). This insect exploits this crop as a nutrient availability as well as a
source of protection. White mango scale infestation on various parts of mango organs such as
leaves, twigs, branches, and roots, with some currently residing inside plant domatia (Peronti,
2001; Miller and Davidson, 2005; Culik et al., 2007). This may injure or kill plants by
depleting sap, injecting toxins, transmitting viruses, or excreting honeydew, which serves as a
medium for sooty moulds (Mitra, 2016).
Table 4.11. Phenology of mango tree and the severity of white mango scale in Bahir Dar
Zuria District from 2020/2021 Cropping season
Phenology Egg Crawlers Adults
Fruit set 76.0a 61.4a 55.4a
Young shoot 67.5b 40.3b 37.4ab
Inflorescence 54.3c 29.2c 23.2ab
Fruit development 46.3d 20.7cd 19.4ab
Sensenced 44.7d 15.8cd 14.5ab
Maturity 21.2e 13.4de 13.2ab
Bud development 16.8f 9.9de 12.2ab
Old shoot 15.0f 8.4 de 5.33ab
Mean 42.7 24.8 22.56
LSD (0.05%) 3.2 9.2 47.05
Mean values in the column of the same letter have not significantly different. Mean values have
the different letter have significant different (P<0.05).
4.3.2. Severity of white mango scale in each growth of mango
White mango scales were recorded in numbers ranging from 42 (7.1) to 9 (1.5) per four leaves
per tree was significant different among the growth stage of mango tree. The infestation of
47
white mango scale was varied in each of them (F 52.83=669.137, P<0.05%) comparing to each
other (Appendix Table.4). The mean severity values of white mango scale for different growth
phase of mango tree was about 56.7, 34.82, 29.7, 21.3 and 18.5 for flowering, yield formation,
late vegetative, early vegetative and establishment stage of the fruit crop respectively (Table,
4.12).
This indicated that the infestation of white mango scale was influenced by the growth phase of
mango tree. The active physiological stage of the mango tree is directly related to the severity
of mango growth. The photo assimilation nature of the mano tree is affected insect pest.
Therefore, leads flower, and fruit set to failure. Study supported that the severity was become
less due to the mango stage being non-physiologically activity. Flowering stage of mango tree
allows for less absorption. The results of the study were supported by Abo Shanaba (2012) in
which the author stated that mature fruits are extensively infested due to immature fruits drop,
and become tiny in size. Moreover, the fruit contained insufficient juice. Finally, the entire
plant might be die (Abo Shanaba, 2012).
Table 4.12. Growth phase of mango tree and the severity of white mango scale in Bahir Dar
Zuria District from 2020/2021 cropping calander
Mango growth Mean + SEm Flowering 56.7(3.09)a Yield formation 34.9(2.74)b Late vegetative 29.7(1.54)b Early vegetative 21.3(0.14)c Establishment 18.5 (0.21)c Mean 31.95 LSD(0.05) 6.5
Mean values in the column of the same letter have not significantly different.
Mean values have the different letter have significant different (P<0.05%).
4.3.3. Seasonal fluctuation of white mango scale
The mean white mango scale infestation was different in the study months (F 17.5=313,
P<.05%) comparing to others (Appendix Table. 5). The maximum number of white mango
scale was recorded in April whereas the minimum insect numbers was recorded in August. The
mean numbers of white mango in the recorded months was described. In June 72.2, May 69.16,
February 50.1, March 48.6, December 39.9, January 38.6, April 34.7, October 26.0, September
22.9, November 22.8, July 20.1 and August 20.5 respectively (Table, 4.13).
This study, therefore, underlines decline and buildup of mango scale population is affected by
rainfall in two ways, even though other contributing factors shall be investigated further. First,
48
minimum amount of average monthly rainfall of about 50mm is required to initiate buildup of
mango scale population, whereas the optimum rainfall for the insect to reach its peak may vary
spatially and temporally, as it was found to be 110mm in April at and 140mm in May at buildup
of mango scale population coincides with mango fruit physiological maturity; both happening
at the beginning of rainy season in the study area.
Studies reported that maturation and ripening of mango fruit begin to take place during the first
months of rainy season as of March-April and continues for few months, vis-à-vis significant
infestation of mango fruits by white mango scale, in western Ethiopia. The study's findings
revealed that white mango scale infestation might be connected directly to the variability of
seasons and precipitation (Ofgaa Djirata and Emana Getu (2015).
Table 4.13. Mean fluctuation of White Mango Scale from August1/ 2020/September 1/2021
in Bahir Dar Zuria District cropping calander
Months Mean severity
June 72.76a
May 69.16b
February 50.1c
March 48.6cd
December 39.9cd
January 38.6cd
April 34.7e
October 26.0ef
September 22.9ef
November 22.8ef
July 20.1ef
August 17.5ef
Mean 38.08
LSD (0.05) 4.9
Mean values in the column of the same letter have not significantly different. Mean values have
the different letter have significant different (P<0.05).
4.3.4. Screening of tolerance mango variety
The severity of white mango scale in different mango variety in Bahir Dar Zuria District
2020/2021 in the study orchards was significantly different in mango tree (F 35.4=2528.3, P<
0.05%) when comparing to the other treatments (Appendix Table.6). The maximum severity
of white mango scale was recorded on Apple mango variety, and the minimum severity of
white mango scale was recorded on Tommy mango variety. The severity of white mango scale
for leaf, stem, fruit, inflorcence and petiole for different mango variety was about 54.4, 63.63,
84.9, 81.7, 61.1 for Apple while 42.5, 51.08, 51.08, 53.9, 58.5 and 59.9 for kitte mango variety
49
while 35.9, 50.4, 42.35, 52.8 and 42.1 for Kent mango, and 31.9, 43.2, 42.3, 64.3 and 40.2 for
local, and 31.7, 34.2, 23.7, 13.6 and 24.4 for Tommy mango variety respectively (Table 4.14).
The result of the study indicated that as Tommy mango exhibited the highest tolerance level in
this investigation, owing to its morphological, physiological, growth habit, and genetical
characteristics. On the contrary, other studies, Apple mango was one of the least infected
cultivars (Ofgaa Djirata, et al., 2016). According to Camacho and Chong's (2015)
investigation, the Tommy Atkin mango variety has the capability to withstand white mango
scale, even though in similar studies, the types mango Alfa and Espada Stahl were highly
susceptible to white mango scale compared to Tommy Atkin mango variety (Rossetto et al.,
2006).
Tommy mango variety was ended up finding to be a more tolerant variety, according to that
studies. Unlike other mango varieties, this fruit crop has a reduced melting chemical
carbohydrate content. Secondly, the morphological characteristics of this type, which is
characterized by a long and dispersed canopy architecture that is exploited for light and air
circulation. Tommy mango has dwarf, compacted, denced, interlocked self-branches structure
and growth habit (Mukherjee and Litz, 1997).
Table 4.14. The severity of white mango scale in each mango variety in Bahir Dar Zuria
District from 2020/2021 cropping season
Variety leaf Stem Fruit Inflorcence Petiole
Apple 54.4a 63.63a 84.9a 81.7a 61.1a
Keitt 42.5b 51.08b 53.9b 58.5b 59.9a
Kent 35.9bc 50.4b 42.35c 52.8bc 42.1b
Local 31.9cd 43.2bc 42.3d 64.3cd 40.2b
Tommy 31.7cd 34.2bc 23.7e 13.6e 24.4c
Mean 39.3 48.5 49.5 52.49 45.6
LSD(0.05) 7.4 9.4 5.6 10.001 4.2
Mean values in the column of the same letter have not significantly different. Mean values
have the different letter have significant different (P<0.05).
4.3.5. Mango tree spacing and the severity of white mango scale
White mango scale severity had shown significantly different in different mango spacing
(F20.64=864.62, P<0.05%) when compared to the other treatments (Appendix Table.11). The
mean maximum severity of white mango scale was recorded on the spacing of 1mx1m while
the mean minimum severity of white mango scale was recorded on 6mx6m.The severity of
white mango scale recorded on different mango tree spacing was about 73.3 for 1mx1m while
50
53.0 for 2mx2m, and 43.4 for 3mx3m while 37.1 for 4mx4m, 29.1 for 5mx5m and 28.6 for
6mx6m mango tree spacing respectively (Table 4.15).
The study indicated that non consistent spacing of mango tree between rows and trees. Spacing
of mango tree is influenced by the ecology. Spacing of 10mx10m in the dry zones and
12mx12m in wet and rich soils is recommended for the production of grafted mango tree. In
the study area, the study area is potential for mango growth in terms of soil fertility and altitude,
but planted them in the marrow spacing (Ngethe et al, 2019).
Planting systems with a high density allow for a greater number of plants per unit area. Mango
trees are normally planted 10 meters apart, with only 100 plants per hectare. The result of the
study indicated that there is no consistency in the spacing used among farmers with others
planting as narrow as 2mx2m leading to the high densities (Dessalegn et al., 2014; Neguse et
al., 2019). Mango tree spacing is influenced by climate, soil fertility and variety. According to
Ngethe et al. (2019) spacing of 10mx10m in the dry zones and 12m x12m in wet and rich soils
is recommended for the production of grafted mango tree (Dessalegn et al., 2014).
Optimum spacing ensures that plants do not compete for growth factors leading to better pest
resistance. Again, avoiding crowded fields reduces the rate at which these pests spread.
Currently, according to this study, as the population density of mango trees grows. Similar
research found that mango fruits planted in high-density planting had a progressive drop in
crop output after 14-15 years due to canopy overcrowding, implying that constant canopy
management was required (Sharma et al., 2006).
Table 4.15. The severity of white mango scale in each spacing of mango tree in Bahir Dar
Zuria District from 2020/2022 cropping season
Intra and Inter row spacing
M/square Mango/hectare Mean severity
1m*1m 1m2 10,000 73.3a 2m*2m 4m2 2,500 53.0b 3m*3m 3m2 1,100 43.4bc 4m*4m 16m2 625 37.1cd 5m*5m 25m2 400 29.1cd 6m*6m 36m2 277 28.6cd Mean 44.2 LSD (0.05) 11.6
Mean values in the column of the same letter have not significantly different. Mean values
have the different letter have significant different (P<0.05).
51
4.3.6. Effects of insecticides on white mango scale
The pre-spraying of the number of white mango scales was from 254 (93.0) to 254 (98.1) per
tree per four leaves, had significant variation (F 1.476=63.0 ns, P >. 05) comparing from other
treatments 12). This had shown uniformly distribution of white mango scale (Appendix Table
.12).
The number of white mango scale in each insecticide seventh day after the first spraying
application was ranged from 99.1(1.7) to 239.3. The number of white mango scale per four
leaves per tree was significantly different in different treatments (F 0.04=72.32, P<.0.05)
comparing others (Appendix Table .13). The mean maximum number of white mango scale
was recorded on Control treatment, on the contrary, the minimum mean number of white
mango scale was recorded on Nimbecidine EC 3% insecticides. The mean number of insects
recorded after the first round application of the insecticides were about 213.0 for local, and
183.0 for Karate EC 5% while 172.7 for Folmit EC 5%, and 148.7 for Nimbecidine EC (40%)
treatments respectively (Table 4.16).
The results of the study indicated that Synthesized Nimbecidine was able to influence the
fecundity potential of white mango scale. Similar studies supported as this insecticide can
control Hemiptera insect orders such as aphid with multiple mode of action (Kora and
Teshome, 2021).
The mean number of white mango scale revealed after second spraying application of the
insecticides was ranged from 44 (3.91) to 92.67 (12.18) per four leaves per tree in different
treatment were significantly different among treatments (F0.0=60.11.08, P<0.05) comparing
to other treatments (Appendix Table. 14). The mean number of white mango scale recorded on
different insecticides was about 253.7 control while 144.4 for Karate EC 3%, and 123.0 for
Folmit EC 5%, and 99.4 for Nimbecidence EC 40% treatments respectively (Table, 4.16).
This indicated that Nimbecidine achieved in the reduction of the number of the nymphs
produced by adults. Kraiss and Cullen, (2008) found that azadirachtin significantly increased
nymphal mortality (80.0 and 77.0% respectively).
52
Table 4.16. The number of white mango scale colonies pre and post application of
insecticides in Bahir Dar Zuria District during 2020/2021 cropping season
Insecticides Before Spraying After 1st spraying After 2nd spraying
Nimbecidine 3%EC 257.7a 148.7d 99.4d
Folmit 40% EC 253.7a 172.7c 123.0c
Karate5% SL 247.4a 183.0b 144.4b
Control(check) 254.4a 213.0a 253.7a
LSD(0.05) 12.712 53.4 3.9
Mean values in the column of the same letter have not significantly different. Mean values
have the different letter have significant different (P<0.05).
4.3.7. Effects of insecticides on white mango scales mortality
The mortality of white mango scale was significantly different among treatments seven days
after the first application (F268.65=682.287, P<0.05) when compared from other treatments
(Appendix Table. 15). The maximum percent mortality of colonies was recorded on
Nimbecidine EC 40% synthetic insecticides, on the contrary, the minimum mortality percent
of colonies were recorded on control treatments. The mean percent of mortality colonies after
the application of different insecticides was about 41.43 for Nimbecidine EC 40% while 36.6
for Folmit EC 5%, and 29.3 for Karate 5%, and about 6.2 for un treated control treatments
respectively (Table, 4.17).
This indicated that the persistent nature of the insecticide influences the insect reproduction.
Nimbecidine has the capability of influencing egg hatchability, and finally the eggs not viability
and the nymphal production was reduced significantly. This ingredient increase development
time of those surviving to adult insects and fecundity of adult’s insects.
Seven days after the second application of different insecticides, the number of colonies was
significantly different (F 630.79=16260.71, P<. 05%) comparing to the other treatments
(Appendix Table.16).
The mean number of colonies mortality after second round application of insecticides were
about 71.1on Nimbecidine 40% while 58.9 for Folmit EC 40%, and 42.3 for Karate SL 5% and
9.7 for untreated control insecticides respectively (Table, 4.17).
This implied as Nimbecidine EC 40% had the capability of persistent nature and multiple
modes of action namely anti-feed ant, volatile repellent, ovipositional deterrent, growth
regulator and sterility. Similar literatures supported as Nimbecidine insecticides have the
enabling potential with the nature of controlling by influencing egg hatchability, and finally the
53
eggs not viability, and the nymphal production was reduced significantly. Nimbecidine
achieved reduction in the number of the nymphs produced by adults (Liu et al., 2001).
The mortality rate of white mango scale using Nimbecidence 3% EC in the 1st and
2nd spraying
was 70.71 and 44.2 respectively, which is the highest compared to others. Also, Bayhan et al.,
(2006) found that Nimbecidine clearly reduced adult longevity, survival rate (zero survival),
fecundity and life table parameter of the aphid. (Liu, et al., 2001). Kraiss and Cullen, (2008)
found that azadirachtin significantly increased nymphal mortality while significantly
increasing development time of those surviving to adult of the insect.
Table 4.17. Mean mortality of white mango scale colonies in Bahir Dar Zuria District from
2020/2021
Insecticides After 1st spraying After 2nd spraying
Nimbecidence 3% EC 41.43a 71.1a
Folmit 40%EC 36.6b 58.9b
Karate 5% SL 29.3c 42.3c
Un treated 6.2d 9.7d
Mean 87.6 87.6
LSD (0.05) 3.0 11.4
Mean values in the column of the same letter have not significantly different. Mean values have
the different letter have significant different (P<0.05).
54
CHAPTER 5. CONCLUTIONS AND RECOMMENDATIONS
5.1. Conclusions
White mango scale insect pest occurred, and distributed in all locations. On the one hand the
infestation of white mango scale increased and on the other hand the plantation status of mango
tree decreased from time to time. This insect pest had several host fruit crops including forest
tree.
There were improper application of mango management practices such as pruning, removal
mechanism of infested branches, planting pattern, plantation system, and irrigation, mulching
and farming system which were aggravating factors for the prevalence and severity of this
insect pest.
White mango scale infested young shoot of mango tree. Young shoot of mango tree was
mostly infested by nymphal stage from white mango scale colonies. The insect pest mainly
influenced fruit bearing stage of mango tree. Tommy atikine mango variety is one of the
tolerant varieties among others. High mortality rate of white mango scale was recorded in
Nimbecidence 3% EC insecticide.
5.2. Recommendations
From the assessment and management of white mango scale study, the following
recommendations are forwarded.
Most of mango producers did not aware regarding to this insect pest so that it should
be interested to give more focus for awareness creation training to mango producers.
Proper agronomic practices are imperative, but, mango orchards were not practiced in
the proper way so that producers have to be practiced with the proper planting system
and planting pattern.
The insect pest influenced other vascular plants beyond mango tree so that producers
and other concerned body should give more emphasis for these newly infested crops.
Combination of proper inter and intra row spacing of mango tree with 6mx6m with
Tommy atikine variety and Nimbecidence (3%) EC insecticide can be the best
management option for the white mango scale.
In addition to assessment and management, dissemination of this study result would be
imperative. Therefore, it is necessary to extend the result of the study as technology of
white mango scale management so that concerned bodies should move it forward to the
mango sector through demonstration and scale out it.
55
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APPENDICES
Appendix Table.1 Base line survey questionnaire
The survey study was carried out in the survey area with structural quationaire. The quatinaire included
quation in each variable. The variables included in the quation were perception, demographic
characteristics, infestation status, adopted mango variety, geographical distribution, occurrence and
severity management practice, host range and status of mango plantation, source of mango seedlings
and mango variety adopted.
Social demographical characterization format
A. Environment (locality)
1.Region------------------zone---------woreda------kebele--------village-----------
2.Location----East----------------North---------------------------Altitude-------------
Name of the farmer---Age----Sex------Martial status-----Education status------
B. Status of mango tree plantation
D. Name of Farmers___________________ State or private farm____________
1. What is your Educational level? 0=no education 1=primary 2=secondary 3=institution
4=university
2. How many mango tree in your mango orchards do you have? Age
3. What was the plantation status of mango tree? A/increase/b/decrease/c/no change
4. If the answer for Q3 is insect, what type of insect?
5. Is there any local name given to this pest?
6. If the answer is ‘Yes’ for Q5 what is the name?
7. Have you pruned mango tree? “Yes’ or No”
8. When the period of time since white mango scale has been known in the survey area? (1)
Below 5 years (2) 5 - 10 years (3) not aware
9. How did you manage white mango scale?
(1) High (2) Medium (3) Low
10. What was the extent of severity in your respective?
(1) High (2) Medium (3) low
11. Which parts of the plants attacked by the pest?
12. By which ways you identify the pest? 1. Color/sign 2. Symptom
13. What is the color/sign you used for identification?
14. What type of mango variety have you planted?
15. How the pests distribute / spread?
16. How long take to spread to your neighborhood farms (week/months)?
17. In which season the white mango scale insect pest become serious?
18. On which farm site you observed the pest infestation were serious?
71
(1) Field farm (2) Backyard (3) No difference (4) Not aware
19. Did you have observation whether the pest was affected the local varieties and exogenous ones
equally or not? (1) Yes (2) No
20. If they answer, no, please ask them the reason why?
21. Did you observe other than mango tree which is attacked by MWS? (1) Yes (2) No
22. If ‘Yes’ for Q21, ask what type of plant?
23. What was the pest prevalence level variation over time?
(1) Increasing (2) Decreasing (3) No change
24. What type of management practice you attempt to control white mango scale?
(1) Cultural (2) Pesticide (3) IPM (4) No measure
25. What are the types of mango tree did you have?
26. If Q24 cultural practices were used as one type of control measure, what type of cultural
practices used?
27. Did the management option you used was successful?
(1) Yes (2) To some extent (3) No (4) Not aware
28. What were the agronomic practice that influence white mango scale?
29. What were the management practice of white mango scale?
30. Did you get extension service for the management of white mango scale? (1) Yes (2) No
31. If the Q30 ‘No’ do you have interest to take
Appendix Table 2: Anova tables of severity in each phenology eggs
Source DF Sum of Squares Mean Square F Value Pr > F
Model 7 11341.29333 1620.18476 472.82 <.0001
Error 16 54.82667 3.42667
Corrected Total 23 11396.12000
Appendix Table 3: Anova table of crawlers in phenology of mango tree
Source DF Sum of Squares Mean Square F Value Pr > F
Model 7 6944.509583 992.072798 35.09 <.0001
Error 16 452.340000 28.271250
Corrected Total 23 7396.849583
Appendix Table 4: Anova table of adult white mango scale
Source DF Sum of Squares Mean Square F Value Pr >F
Model 16 5593.65958 799.09423 1.08 0.4189
Error 23 738.89875 17416.03958
Corrected Total 11822.38000
72
Appendix Table 4: Anova of mango growth phase and severity
Source DF Sum of Squares Mean Square F Value Pr > F
Model 4 2676.550667 669.137667 52.83 <.0001
Error 10 126.666667 12.666667
Corrected Total 14 2803.217333
Appendix Table 5: Anova table of Seasonal fluctuation of white mango scale
Source DF Sum of Squares Mean Square F Value Pr > F
Model 11 12014.20306 1092.20028 129.54 <.0001
Error 24 202.36000 8.43167
Corrected Total 35 12216.56306
Appendix Table 6: Anova table of tolerant mango variety leaf of mango tree
Source DF Sum of Squares Mean Square F Value Pr > F
Model 4 2157.415333 539.353833 14.05 <.0001
Error 25 959.418333 38.376733
Corrected Total 29 3116.833667
Appendix Table 7: Anova tables of on stem parameters
Source DF Sum of Squares Mean Square F Value Pr > F
Model 4 2836.624667 709.156167 11.48 <.0001
Error 25 1544.150000 61.766000
Corrected Total 29 4380.774667
Appendix Tables 8: Anova table of fruit of mango tree
Source DF Sum of Squares Mean Square F Value Pr > F
Model 4 12256.32533 3064.08133 121.42 <.0001
Error 25 630.88833 25.23553
Corrected Total 29 12887.21367
Appendix Table 9: Anova tables of inflorcence of mango tree
Source DF Sum of Squares Mean Square F Value Pr > F
Model 4 10113.20867 2528.30217 35.74 <.0001
Error 25 1768.53833 70.74153
Corrected Total 29 11881.74700
Appendix Table 10: Anova tables of petiole of mango tree
Source DF Sum of Squares Mean Square F Value Pr > F
Model 4 5597.520000 1399.380000 111.98 <.0001
Error 25 312.406667 12.496267
Corrected Total 29 5909.926667
Appendix Table 11: Anova table intra and inter row spacing of mango tree
Source DF Sum of Squares Mean Square F Value Pr > F
Model 5 4323.111111 864.622222 20.64 <.0001
Error 12 502.666667 41.888889
73
Corrected Total 17 4825.777778
Appendix Table 12: Anova table before spraying of the insecticides
Source DF Sum of Squares Mean Square F Value Pr > F
Model 2 126.0000000 63.0000000 1.40 0.2965
Error 9 406.2500000 45.1388889
Corrected Total 11 532.2500000
Appendix Table 13: Anova Table after 1st spraying of the insecticides
Source DF Sum of Squares Mean Square F Value Pr > F
Model 2 144.66667 72.33333 0.04 0.9597
Error 9 15772.00000 1752.44444
Corrected Total 11 15916.66667
Appendix Table 14: Anova after 2nd spraying application of the insecticides
Source DF Sum of Squares Mean Square F Value Pr > F
Model 2 22.16667 11.08333 0.00 0.9976
Error 9 41928.75000 4658.75000
Corrected Total 11 41950.91667
Appendix Table 15: Anova Table of mortality of white mango scale after 1st
Source DF Sum of Squares Mean Square F Value Pr > F
Model 3 2061.862500 687.287500 268.65 <.0001
Error 8 20.466667 2.558333
Corrected Total 11 2082.329167
Appendix Table 16: Anova Table after second application
Source DF Sum of Squares Mean Square F Value Pr > F
Model 3 6382.443333 2127.481111 58.26 <.0001
Error 8 292.113333 36.514167
Corrected Total 11 6674.556667
Appendix Figure 1. Process of host plant of white mango scale identification
74
Appendix Figure 2. Host plants of white mango scale identified
Appendix Figure 3. Mango varieties adopted in the farm of mango
A. Local mango
B. Tommy mango
C.Keitt mango
D.Apple mango E. Kent mango
75
Appendix Figure 4. Experimental site and tested chemicals
76
Appendix Figure 4: Meteorological data of the study area
Element: Monthly Rain fall
Station: Zenzelima
Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2011 1.5 0.0 16.4 13.3 137.1 162.9 384.8 377.5 311.6 72.3 33.7 0.8
2012 2.1 0.0 3.5 1.0 21.3 209.4 442.2 408.1 361.6 29.8 23.2 33.9
2013 0.0 0.0 0.0 0.0 110.7 178.3 683.5 421.2 170.0 203.8 34.1 0.0
2014 2.8 2.1 38.2 49.6 177.3 112.2 339.6 387.4 223.7 104.1 3.2 0.0
2015 na na na na na na na na na na na na
2016 0.0 0.0 6.0 18.9 186.0 333.3 351.0 na 138.9 80.5 0.0 0.0
2017 0.0 17.3 1.7 39.6 94.3 53.3 837.4 334.2 193.7 101.8 0.0 na
2018 1.4 na 37.7 na na 30.1 370.4 210.7 26.6 na na na
2019 1.6 9.5 na 4.0 96.8 na 422.5 na na na 99.6 na
2020 2.3 9.9 4.3 71.3 285.3 359.8 455.2 229.1 na na na 8.6
mean 1.2 3.9 10.8 19.8 110.9 143.9 428.7 236.8 142.6 59.2 19.4 4.3
total 11.7 38.8 107.8 197.7 1108.8 1439.3 4286.6 2368.2 1426.1 592.3 193.8 43.3
1.3 4.85 13.475 24.7125 138.6 179.9125 476.2889 338.3143 203.7286 98.71667 27.68571 7.216667 1514.801
Months Rainfall (mm) Maximum temprature (oC) Minimum teprature (oC)
Jan 1.2 25.7 12.6
Feb 3.9 29.8 12.1
Mar 10.8 30.5 14.2
April 19.8 25.7 12.6
May 110.9 25.6 11.5
June 143.9 24.4 11.1
July 428.7 24.9 9.2
Aug 236.8 24.8 9.1
Sep 142.6 24.1 9
Oct 59.2 22.3 9.02
Nov 19.4 21.8 9.01
Dec 4.3 20.5 9.05
Mean 25 10.7
Total 1181.5
Appendex table 1. Mean monthly rainfall (Zenzelma station), monthly minimum and maximum tempratures (Bahir Dar station) for the years from 2011 to 2020
source : Bahir Dar meteorology service agency, 2021
0
5
10
15
20
25
30
35
0
50
100
150
200
250
300
350
400
450
500
Ja
n
Fe
b
Ma
r
Ap
ril
Ma
y
Ju
ne
Ju
ly
Au
g
Se
p
Oct
No
v
De
c
Tem
pratu
re (o
C)
Rain
fall (m
m)
Months
Rainfall (mm) Maximum temprature (oC) Minimum teprature (oC)
77
BIOGRAPHICAL SKETCH
The author of this paper was Alebel Eskezia Adam. He was born from his Mother Fenta Asaye and his
Father Eskezia Adam in Yilmana Densa District in Adet Town in Amhara Region Ethiopia in
1980.When his age reached for education, he had started to learn in Adet Town. He had learnt from
grade 1-6 in Adet Gafat Primary school, from 7-8 in Adet junior school and from 9-12 in Adet secondary
and preparatory school.
The author had got his first degree in plant science in 2005 E.C in Debre Markos University. He worked
in different Agricultural Research Centers in different plant protection disciplines in weed and insect
management research case team. From 2006 up to 2009 in Amhara Region Agricultural Research
Institute in Sirinka Agricultural Research Center in North Wollo from 2009 up to 2012 in Amhara
Region Agricultural Research Institute (ARARI) in Adet Agricultural Research Center. Currently He
has worked in Fogra Rice Research and Training Center in Ethiopian Agricultural Research Institute
(EIAR) in insect pest management research directorate.