ABSTRACT
Mango (Mangifera indica L.) is an important fruit crop in Nigeria. It is a source of essential vitamins and is also cultivated for its nutritional, medicinal and industrial uses. Fruit flies infest various commercial fruit crops and cause economic damage. Mass trapping and male annihilation technique (MAT) has been the most useful and common means of controlling fruit flies with special focus on Bactrocera dorsalis Hendel (Diptera: Tephritidae) on mangoes. This study was conducted during the mango fruiting period of April/May 2019 season, when the density of fruit flies was at their peak. It evaluate the effectiveness of four types of parapheromones namely, Methyl eugenol (liquid and solid forms), Cuelure, Terpinyl acetate and Trimedlure for mass trapping of fruit flies on Mango and the effect of the parapheromones on the mean number of flies trapped. Modified Lynfield traps containing the parapheromones were randomly set on the mango orchards in three replicates in National Horticultural Research Institute (NIHORT) orchard, Okigwe, Imo State, Southeast Nigeria. Effect of parapheromones on mean number of damaged dropped fruits was also evaluated. The mean populations of B. dorsalis and Ceratitis cosyra were significantly higher (P>0.05) in liquid methyl eugenol traps when compared to other parapheromones. B. dorsalis recorded more than 90% of the fruit flies that were trapped especially in the first 3 weeks of trapping. In orchard I, Liquid Methyl eugenol significantly (P<0.05) trapped highest number of B. dorsalis (270.20) in week 1. Mean population value (131.8) for Liquid Methyl eugenol was significantly different from all other treatments in both orchard 1 and 2. There was steady decline in damaged dropped mango fruits as the study progressed (Figures 4.1 and 4.2). Use of liquid Methyl eugenol was most effective in trapping B. dorsalis and C. cosyra, and it can be incorporated in Integrated Pest Management (IPM) programmes for the control of fruit flies.
Keywords: Mangifera indica, Ceratitis cosyra, Bactrocera dorsalis, mass trapping, Parapheromones, Lynfield trap
TABLE OF CONTENTS
Title
page ii
Declaration iii
Certification iv
Dedication v
Acknowledgements vi
Table
of Contents vii
List
of Tables x
Lists
of Figures xi
List of Plates xii
Abstract xiii
CHAPTER 1: INTRODUCTION
CHAPTER 2: LITERATURE
REVIEW
2.1
Taxonomy of the Oriental Fruit Fly 8
2.2
Mango Production Overview 8
2.3
Economic
Importance of Mango 10
2.4
Production
Constraints of Mango in Nigeria 11
2.5
General Overview of Insect Pests and Diseases
of Mango 12
2.6
Economic
Impact of Tephritid Fruit Flies 12
2.7
Interaction
Studies Between Native and Invasive Fruit Flies 13
2.8
Description of Oriental Fruit Fly (Bactrocera
dorsalis) 14
2.8.1
Life
cycle and damage symptoms 15
2.8.2 Taxonomy and
nomenclature of fruit flies 17
2.8.3 Distribution of fruit
flies 18
2.9
Fruit Fly Management Techniques 19
2.9.1
Fruit
fly monitoring 19
2.9.2
Protein baits 22
2.9.3
Male annihilation technique (MAT) 26
2.9.4
Female
biased traps 27
2.9.5
Physical protection 29
2.9.6
Sanitation
and farm hygiene 32
2.9.7
Biological control 34
2.9.8
Sterile insect release
method 35
2.9.9
Post harvest (regulatory
control) 36
CHAPTER
3: MATERIALS AND METHODS
3.1
Study Site 38
3.2 Experimental Design 38
3.3 Trapping Tools and
Placement of Traps 38
3.4
Data Collection 44
3.5
Percentage Damaged Fruits 44
3.6 Statistical Analysis 45
CHAPTER 4: RESULTS AND DISCUSSSION
4.1 Mean
Population of B. dorsalis Trapped
with Different
Parapheromones in
Mango Orchard 1 in NIHORT,
Okigwe 46
4.2 Mean Population of C. cosyra Trapped with Different
Parapheromones in
Mango Orchard 1 in NIHORT, Okigwe 49
4.3 Mean
Population of B. dorsalis Trapped
with Different
Parapheromones in
mango orchard 2 in NIHORT,
Okigwe 52
4.4 Mean
Population of C. cosyra Trapped with
Different
Parapheromones in
Mango Orchard 2 in NIHORT, Okigwe 55
4.5 Dropping of Infested Mango Fruits 58
4.6 Mean Population of B. dorsalis and C. cosyra Trapped
on
Mango in Orchard 1 and
Orchard 2 in NIHORT, Okigwe 61
4.7 Discussion 63
CHAPTER 5: CONCLUSION AND
RECOMMENDATIONS
5.1 Conclusion 65
5.2
Recommendations 65
REFERENCES 67
LIST OF TABLES
4.1 Mean population of B.dorsalis trapped with different
parapheromones
in orchard 1 in NIHORT, Okigwe 47
4.2
Mean population of C. cosyra trapped with different
parapheromones in orchard 1 in NIHORT, Okigwe 50
4.3
Mean population of B.dorsalis trapped with different
parapheromones in orchard 2 in NIHORT, Okigwe 53
4.4
Mean population of C. cosyra trapped with different
parapheromones in orchard 2 in NIHORT, Okigwe 56
LIST
OF FIGURES
4.1 Percentage
damaged mango fruits in orchard 1 59
4.2 Percentage
damaged mango fruits in orchard 2 60
4.3 Mean
population of B. dorsalis and C. cosyra trapped in
NIHORT, Okigwe 62
LIST
OF PLATES
1:
Life history of Bactrocera spp. 16
2:
Parapheromone treatments used in the
Study 41
3:
Modified Lynfield trap 42
4:
Setting up the traps 43
5:
Catches of B. dorsalis 48
6:
Catches of C. cosyra 51
7:
Trapped fruit flies for week 1 in
Orchard 2 using liquid
methyl eugenol 54
8:
Trapped fruit flies for week 4 in
orchard 2 using solid
methyl eugenol. 57
CHAPTER 1
INTRODUCTION
Fruit
flies of the family Tephritidae in the order Diptera; are the largest and
phylogenetically diversified group known as acalypterate flies. (Steck, 2008).
These are commonly called fruit flies due to their close association with
fruits and vegetables. Of the 4500 known
species of fruit flies worldwide, nearly 200 are considered as pests, but about
70 species are regarded as agriculturally important throughout the world
(Clarke et al., 2005). Freidberg (2006) stated that only about 5 per
cent of all tephritid species are economically important.
The
genera Bactrocera and Ceratitis in the tropical and
subtropical regions of Africa consists of over 500 well distributed species
(Smith et al., 2003). Oriental fruit
fly Bactrocera dorsalis (Hendel)
is the most invasive and notorious pest of mango and other horticultural
crops (Rwomushana et al., 2008).
Sub-Saharan Africa is the native home to 915 fruit fly species from 148 genera,
of which 299 species grow in either wild or cultivated fruits (Ekesi, 2012). In
the tropics, fruit fly devastation is further compounded by the predominantly
conducive weather conditions and the availability of host fruits throughout the
year. With intensified fruit trade, the
African continent has also become exposed to introduction of alien invasive
fruit fly species (Ekesi, 2012). Fruit flies identified in major Mango-producing areas in Nigeria
according to Umeh et al. (1998) belong to the genera Bactrocera, Ceratitis,
Dacus and Trirhithrum. Besides fruit crops, they are also
destructive to many vegetables, oilseeds and ornamental plants (Hanna et al., 2008). Female fruit flies lay
eggs in fruits and destroy more than 400 diverse fruits
and vegetables comprising mango,
guava, citrus, melon, papaya, peach, passion fruit, plum, apple and star fruit.
The
Mediterranean fruit fly Ceratitis
capitata Wied. (Diptera: Tephritidae), also known
as medfly, is regarded as one of the most important fruitfly pests worldwide
(Malacrida et al.,
2007). The species affects fresh fruit production, regional and international
trade of mangoes, due to its high fecundity rate (CABI, 2014). C. capitata originated from sub-Saharan
Africa (Gasparich et
al., 1997), and has spread
to the Mediterranean basin countries and from there it had become a global
invasive threat. It is currently found in Latin America, the Middle East,
Australia and the Hawaiian islands, with invasions in the US mainland
(Malacrida et al.,
2007). It is widely dispersed in South America, with the solely exception of
Chile (CABI, 2014).
Various management strategies, such as the use
of food baits, parasitoids, pathogens, field sanitation, fruit bagging, sterile
insect technique (SIT), bait application techniques (BAT) and male annihilation
technique (MAT) are presently used for the control and management of many
species of fruit flies (Ekesi and Billah, 2007). There are different control
measures against Bactrocera dorsalis and
Ceratitis capitata, Asawalam et al., (2009) reported that the use of Methyl
eugenol and nulure placed in Lynfield trap proved to be one of the best
alternatives for the control of Bactrocera
dorsalis. They observed an improvement in the taste and quality of the
citrus, after trapping the fruit fly. This work was designed to evaluate the efficiency
of some more recently available but yet untested Parapheromones in the Nigerian
market.
Methyl
eugenol (ME) baits are also being used to monitor and control male fruit flies
but it is not potentially effective against gravid females that lay eggs on
maturing fruits and aid in spread of the local population of fruit flies (Shelly and Edu, 2008). Parapheromones enhance breeding performance
in male fruit flies that have been exposed to them and they do not usually
attract female fruit flies. Although ME-based MAT has been used either alone or
in combination with other fruit fly control techniques for management of fruit
flies, using it alone for management of fruit flies in Africa needs to be
assessed.
In
sub-Saharan Africa, where the pest is now well distributed, MAT is applied on
limited bases usually in integration with other control strategies (Vargas et
al. 2008; Ndlela et al., 2016).
In Kenya, an IPM package, aiming several species and stages of fruitflies,
comprising of (1) spot use of bait spray, (2) MAT, (3) parasitoid release, (4)
biopesticide use and (5) orchard sanitation, is being encouraged and applied in
diverse major mango-growing zones (Ekesi and Billah, 2007; Ekesi et al.,
2007, Ekesi, 2010). This initiative has caused a severe decrease of target
fruit fly pest populations, especially B. dorsalis. This has led to
production of high-quality fruit that has also opened access to export markets.
Parapheromones are chemicals that are not
naturally used in intraspecific communication but which do elicit responses
similar to true pheromones. Parapheromones are produced for use both in
commercial liquid state and polymeric plugs in the form of a controlled-release
formulation. The parapheromone Methyl eugenol (ME) has high rate of capture on
species of the genus Bactrocera (including B. dorsalis, B.
zonata, B. carambolae, B. dorsalis, B. philippinensis and
B. musae) (IAEA, 2003). However, several studies
(Nishida et al., 1988a, b; Tan and Nishida, 1995,
1998, 2007; Tan et al., 2011) have
showed that definite male lures (e.g., Methyl eugenol, raspberry ketone, and
zingerone) are applied in synthesizing male sex pheromones, and so the original
definition of parapheromone does not applies to tephritids. Most parapheromones
are also known to attract a particular species of fruit fly (Fay, 2012).
Tephritids had evolved sophisticated mating systems over the decades
and plants exudates play an important role in shaping male lekking and mating
success in many ways (Diaz-Fleisher and Aluja,
2000). A fruit fly with a narrow host range prefers
mating on the plant parts that encourage mating activities. This is the case of
the apple maggot fly, Rhagoletis pomonella
(Walsh) where males rest on host fruit waiting for the females, with which they
mate upon arrival (Shelly and Dewire, 1994). Most Tephritidae species are
polyphagous, therefore, predicting female location is difficult, but males
aggregate and release sex pheromone in groups (termed leks) to attract females
(Tan and Nishida, 1996).
Plant compounds have also been found to affect sexual
communication in these lekking species. Bactrocera
dorsalis (Hendel) males are known to ingest methyl eugenol, a natural
compound found in certain species of plants, which serves as a precursor in the
synthesis of sex pheromone and enhance the attraction of females (Nishida et al., 1997). Likewise Bactrocera tryoni (Froggatt) showed an
enhancement of mating success, most likely related to changes in pheromone
composition when males fed on cuelure and zingerone (Kumaran et al., 2013; Kumaran et al., 2014). Although the mechanisms
underlying this phenomenon are less understood than for B. dorsalis, the increase in mating success seems to be related to
an increase in male pheromone calling behavior
(Shelly et al.,
2008). For Ceratitis capitata (Wiedemann), the exposure of males to fruit
volatiles increases male mating success (Shelly and McInnis, 2001; Shelly and
Villalobos, 2004; Papadopoulos et al., 2006). This research looked at
the activities and efficiency of this various parapheromones in trapping the
fruit flies in the region of the study.
Suppression or elimination as a control measure of
fruit flies population is of extreme significance for the economy of growing
countries whose income is greatly relying on agriculture. Pre-harvest
management techniques for fruit flies comprise control techniques like the
application of baiting and male annihilation techniques (MAT), Sterile Insect
Technique (SIT), biological control (entomopathogens, parasitoids and
predators), fruit bagging, early harvesting, and orchard sanitation (Allwood,
2000; Barnes, 2004; Mau, et al.,
2007; Ekesi and Billah, 2007). To permit entrance to quarantine sensitive
markets, pre-harvest technologies are supplemented with postharvest methods
such as fumigation, heat treatment, cold treatments and irradiation (Ekesi and
Billah, 2007).
The effectiveness of most of these management
techniques rely on the capacity to create economical rearing methodologies. To
conduct preliminary study on biology, response to attractants, and
effectiveness of the several biological control agents, a steady supply of good
quality insects of pre-determined reproductive stages and age is essential.
Early tephritid management strategies
used products like fermenting sugar baits, yeast and sub-products of liquor
industry such as
brewers’ yeast and related products, protein improved by hydrolysis of proteins
and
ammonium solutions among
others to attract the fruit flies (Epsky
et al., 2014).
Currently,
protein baits are not very effective they attraction range are limited and they
attract mainly female fruit flies. Evaluating the effectiveness of available
parapheromones in the local market can help small scale farmers to adequately
control the fruit flies and
inform
them of the best use practices. Majority
of farmers in the country are not acquainted with efficient fruit fly control
options, hence, mango production in Nigeria is currently being
constrained by the attack of B. dorsalis. Current control
measures against fruit flies mainly incorporate the use of insecticides
as a cover spray or bait and targeting the adult flies (Raga and
Sato, 2006).
The
key advantage of mass trapping method is exclusion of fruits and whole
canopy by contamination of insecticide sprays. The mass trapping methods
can be applied by traps of different constructions, which have to be set
on the tree canopy. The traps are filled with different types of attractants
and treated by insecticide, or they could be filled with
attractant-insecticide water solution (Bjeliš, 2006). Mass trapping has been
reported to show better efficacy over bait sprays and it has lower cost of
application especially human labour ( Bjeliš, 2006.) Traps designs and
efficacy of the parapheromones, including different colors and shapes, are
essential to obtain a high efficacy in fruit fly catches. Since, these
parapheromones have varying rates of attracting and trapping the fruits, they
need to be evaluated.
The
agricultural industry has been experiencing losses due to spoilage and fruits
which fall extensively prior to maturity as well as deformed fruits which are
not appreciated on the market. Little information is available on the fruit
flies of Burundi (Ndayizeye
et al., 2017),
and this is true of our country too. Recent studies of Ugwu et al., (2018) reported that
horticultural farmers in Nigeria, which are small scale farmers that are
responsible for the
large percentage of fruit production, are seeing the magnitude of damage. They
are not aware of the existence of these pests and the identification of the
major pests is required to develop an effective control strategy (Mwatawala et al., 2009). The identification of
species is possible with parapheromones (Modjonnesso et al., 2012; Vargas et al., 2013).
Large proportions of yields are lost annually due to fruit fly damage from not
using food baits. Cost of importation, clearance and delay at the ports are some
of the major reasons that prevent the local farmers from gaining access to
these protein baits. To prevent these constraints; development, improvement and
assessment of the efficacy of indigenous baits may offer substitutes for
small-scale and medium-scale growers to improve fruit fly trapping, and for
suppression of the fruit fly population (Epsky et al., 2014). Since
parapheromones are common and are widely used, their efficacy and cost
effectiveness evaluation is required.
Objectives of the
Study
The objectives of this study were to:
i.
Evaluate the use of
Parapheromones for mass trapping of B.
dorsalis and C. cosyra
populations on mango.
ii.
Determine whether there
will be population reduction of the fruit flies after application of the parapheromones.
iii.
Evaluate the levels of
trapping of B. dorsalis and C. cosyra by the parapheromones.
iv.
Determine the level of damage
of the mango fruits at the application of the parapheromones.
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