STUDY ON MAJOR BIOLOGICAL AND ECOLOGICAL CHARACTERISTICS OF FRUIT FLY Bactrocera dorsalis Hendel ON FRUIT TREES AND CONTROL METHOD IN INTEGRATED PEST MANAGEMENT APPROACHES IN MOC CHAU, SON LA PROVINCE

MINISTRY OF EDUCATION
AND TRAINING
MINISTRY OF AGRICULTURE AND
RURAL DEVELOPMENT
VIETNAM ACADEMY OF AGRICULTURAL SCIENCES
******


NGUYEN THI THANH HIEN


STUDY ON MAJOR BIOLOGICAL AND ECOLOGICAL
CHARACTERISTICS OF FRUIT FLY Bactrocera dorsalis Hendel
ON FRUIT TREES AND CONTROL METHOD IN INTEGRATED
PEST MANAGEMENT APPROACHES
IN MOC CHAU, SON LA PROVINCE

Major: Plant Protection
Code: 62.62.01.12


SUMMARY OF AGRICULTURAL DOCTORATE THESIS



HANOI, 2014


The thesis was completed at:
Vietnam Academy of Agricultural Sciences

Supervisor:
1. Dr. Le Duc Khanh
2. Prof. Dr. Pham Van Lam

Peer reviewer 1:
Peer reviewer 2:
Peer reviewer 3:

This thesis will be defended at Thesis evaluation committee in
Vetnam Academy of Agricultural Sciences
At hour, date month year

The thesis can be accessed at:
1. Vietnam national library
2. Library at Vietnam Academy of Agricutural Science
3. Library at Plant Protection Research Institute
1
INTRODUCTION
1. Rationale
Oriental fruit fly, Bactrocera dorsalis Hendel (Diptera: Tephritidae), is an
important pest on fruit trees since larvae feed on and cause direct damage to fruits.
Furthermore, the oriental fruit fly is also in a list of quarantine pest for fruits
imported from Vietnam for many countries. Presently, control of fruit fly in
general and Oriental fruit fly in particular is based on bait traps to lure and kill
adult males and chemical pesticides, however these methods did not provide an
effective control. Current researches on biology and control of oriental fruit fly are
limited and do not provide effective tools for control of fruit fly in fruit tree
production. Management of fruit fly is an urgent need in agricultural production as

it challenges fruit production and export of Vietnam.
Hence this study has been conducted to “Study on major biological and
ecological characteristics of fruit fly Bactrocera dorsalis Hendel on fruit trees
and control method in integrated pest management approaches in Moc Chau,
Son La province”.
2. Objective
To study biology, ecology of fruit fly and other factors affecting occurrence
and abundance of fruit fly B. dorsalis in order to develop an effective and sustainable
integrated pest management (IPM) program to control B. dorsalis on local H’Mong
peach in Moc Chau, Son La province and other fruit trees in Vietnam.
3. Scientific and practical importance
- Comprehensive understanding biological, ecological characteristics and
other factors affecting the occurrence and development of B. dorsalis in Moc
Chau, Son La province at pre-harvesting stage of H’Mong peach.
- Successful development of IPM control program for oriental fruit fly B.
dorsalis based on its biological and ecological characteristics. Results from this
study provide effective tools for control of B. dorsalis on fruit trees in Vietnam
and particularly in Moc Chau, Son La province.
4. Scopes of study
4.1. Target insect pest
Oriental fruit fly B. dorsalis Hendel
4.2. Scopes of study
Comprehensive study on biological, ecological characteristics of oriental
fruit fly B. dorsalis. Develop and implement IPM program for control of this fruit
fly species taken to a case study in Moc Chau, Son la province.
5. Novel aspects of the study
- Determined and classified 21 fruit fly species on 31 host fruit trees in
Hanoi, Hoa Binh, Son La and Lao Cai provinces. A list of 21 fruit fly species on
20 different host fruit trees was also determined for Moc Chau, Son La province
for the first time.

- Provided a systematic literature reviews on biological and ecological
characteristics of oriental fruit fly B. dorsalis.
2
- Recommended an IPM program for control of oriental fruit fly B. dorsalis
in large fruit plantation area in Moc Chau, Son La province.
6. Structure of the thesis
This thesis consists of 119 pages including introduction; material, method;
results (containing 3 chapters); and discussion and recommendation. The thesis
also contains 19 Tables and 29 Figures. Ninety seven literatures have been
reviewed and cited in the thesis including 31 Vietnamese studies and 66 English
publications.
CHAPTER 1. LITURATURE REVIEW
1.1. The basic scientific of project
Fruit flies (Diptera: Tephritidae) are diversity in species composition and broad host
range of fruits (Ian and Marlence, 1992). However, the species composition of fruit flies is
differences in each ecological zones and the change is mainly dependent on the structure of
their host fruits
Larvae (maggots) of fruit flies lives and damages inside of fruits. Therefore,
the study of population dynamic of fruit flies can only observation through the
activities of fruit fly matures into traps.
Habitat of fruit fly larvae are inside fruits therefore the control methods
(including chemical methods) are usually ineffective. The scientific data on the
change of mature population dynamic are important for propose of the suitable
time to control of fruit flies.
Population variation of fruit flies in specific conditions will be important
scientific information for construction a suitable, sustainable and effective method
to control of fruit flies
1.2. International studies on fruit fly
1.2.1. Species composition, distribution and economic importance of fruit fly
Oriental fruit fly B. dorsalis was first recorded in Taiwan in 1912. Since then

it was found in many other regions in Asia and Pacific including India, Pakistan,
Nepal, Vietnam, Laos, Thailand and others (Wan et al., 2011). Oriental fruit fly is
among the most 5 important fruit fly species in Southeast Asia.
1.2.2. Biological characteristics of Oriental fruit fly B. dorsalis
1.2.2.1. Living behavior: Matured females and males oriental fruit fly and other
fruit fly species in general look for preferred host plants for their nutrient food
sources, particularly protein source to mate and lay eggs on. Fruit fly species
living in different climate conditions prefer different host plants as place for
mating. Oriental fruit flies are attracted to yellow color. Tropical fruit flies usually
choose ripen fruits with soft peel to lay eggs on (Allwood and Ema, 2003).
Developmental periods for egg, larval and pupal stages are 1-20 days, 9-35
days and 10-30 days, respectively. Adults live for 1-3 months (Ian and Marlene,
1992). A female adult can lay average 1,236.2 eggs or 10.2 eggs per day in
laboratory rearing conditions. Naturally developmental factor for Oriental fruit
flies is 0.14; population multiple factor for a generation is 712; a life cycle for a
generation is 50 days; and time period to double a population is approximate 4.3
3
days (Pablo Liedo and James Carey, 1996). Vargas et. al. (1997) also studied
biology of Oriental fruit flies and reported these factors for 560,2 for multiple
factor; 0.14 for developmental factor; 77,4 days for a life cycle; and 4,9 days for
double a population. Host range includes plant species in family Euphorbiaceae, 2
species in family Rhamnaceae and 3 species in family Rosaceae (Ian and Marlene,
1992). Hui and Jian (2005) reported 100 different fruits as food source for oriental
fruit fly larvae.
1.2.3. Ecological characteristics of oriental fruit flies
1.2.3.1. Impact of temperature on growth and development of Oriental fruit flies:
Temperature has strong impact on the growth and development of Oriental fruit
flies. Time period for egg, larval, and pupal stages developed at 30°C is as short as
half of their developmental time at 20°C (Liu et al., 1985). Likewise, it takes
females B. dorsalis 30.4 days pro-oviposition at 19°C, however this period is just

17.4 days at 36°C (Yang et. al., 1994). Hence, the total life cycle is also
temperature dependent. The life cycle of Oriental fruit flies varies from 102 days,
to 77 days and 38 days at 20°C, 25°C and 30°C, respectively (Liu et al., 1985).
Similarly, other study also shows a strong reversible correlation between life cycle
of B. dorsalis and temperature, i.e. life cycle of B. dorsalis varies from 133,2;
77,4; 45,1; 33,4 to 28 days at 16°C, 18°C, 24°C, 29°C and 32°C, respectively. The
number of eggs laid by a female increases as temperature increases from 16°C to
24°C, i.e. 40.8 eggs per female at 16°C, 690.6 eggs per female at 18°C; and 1,512
eggs per female at 24°C; thereafter, females lay less eggs as temperature increases,
i.e. 602.8 eggs per female at 29°C; and 77.9 eggs per female at 32°C. Furthermore,
temperature is also known to have impact on survival of B. dorsalis at different
developmental stages (Vargas et. al., 1997).
1.2.3.2. Effect of nutrition on growth and development of oriental fruit flies :
Food source and nutrition cause difference in the maturity of larvae oriental fruit
flies. Developmental time for larval stages of B. dorsalis is 19; 23; 18.5; and 26
days as feeding on Robuta and Elakki banana, guava, papaya and mango,
respectively (Liu et. al., 1985).
Nutrition and diet also affect on sex ratio of B. dorsalis. Sex ratio for B.
dorsalis feeding on mango is 1:1.7 for male: female. This ratio varies on different
food source, i.e. 1.09:1; 1.0:1.0; 1.0:0.92; and 1:1.09 when fed on guava, papaya,
Robuta banana and Elakki banana, respectively. Feeding on diet containing
protein, soya flour and soybean protein results in the sex ratio of 50.5% male: 49.5
% femal (Khan et. al., 2011).
1.2.3.3. Occurrence and factors affecting occurrence of B. dorsalis
Occurrence, development and population abundance of B. dorsalis have been
intensively studied in Thailand, China and Hawaii (Frank and Henrry, 1970;
Keawchoung et. al., 2000; Yuan Meng et. al., 2008, Zhou et. al., 2008). Several
abiotic factors greatly affect population abundance and occurrence of B. dorsalis
including moisture (Allwood and Ema, 2003; Amice and Sales, 1995; Nripendra
and Hirak, 2010), temperature (Wu et. al., 2000; Frank et. al., 1970; He et. al.,

4
2002), and nutrition and diet (Amice and Sales, 1996; Leweniqila et. al., 1996; Ye
and Jian, 2005; Vargas et. al., 1990).
1.2.4. Control of fruit flies
Several control methods have been recommended for control of fruit flies as follow:
- Plant quarantine: fumigation using fenthion, dimethoate, Methyl bromide,
Ethylen dibromide; radiation treatment; cold and hot temperature treatment, hot
water treatment, hot water vaporization treatment and hot vaporization treatment;
- Cultivation method: change planting season, field sanitation, early
harvesting (Allwood, 1996; Khandelwal and Nath, 1978; Susanto and Tati, 1971;
Vijayseganran, 1996);
- Physical method: fruit packaging, pheromone traps, food traps (Drew and
Romig, 2010; Pinero et. al., 2010; Vickers,1996);
- Sterilization method: Pupa sterilization using Coban 60 and Cesium 137
implemented in Thailand, Japan and other countries (Obra and Resilva, 2011;
Orankanok et. al., 2011);
- Biological control: use parasitoid wasp as implemented in Hawaii and Fiji;
- Chemical control: application of chemical insecticide cover all plant canopy;
- IPM program: successfully prevent the immigration of fruit flies from
intercrop hosts and surroundings to commercial production fields.
1.3. In country literature review
1.3.1. Species composition, distribution and economic importance of fruit flies
B. dorsalis has been reported damaging in all fruit production areas in
Vietnam (Viện Bảo vệ thực vật, 1967-1968; 1997-1998; Drew et. al., 2001; Le
Duc Khanh et. al., 2008; 2010; Dang Xuan Ky et. al., 2008; Le Thi Dieu and
Nguyen Van Huynh, 2009; Nguyen Thi Thanh Hien et. al., 2011; 2012).
Several studies on species composition of fruit flies have also been
conducted in Long An province (Le Thi Dieu and Nguyen Van Huynh, 2009),
Tien Giang province (Viện Nghiên cứu cây ăn quả miền Nam, 2011) and Binh
Thuan province (Nguyen Thi Thanh Hien et. al., 2011).

1.3.2. Biological characteristics
Biological characteristics of B. dorsalis have been published by several
authors (Huynh Tri Duc et. al., 2001; Duong Minh Tu et. al., 2001; Nguyen Huu
Dat, 2003; 2007; Nguyen Huu Dat and Bui Cong Hien, 2004, Vo Thi Bao Trang
et. al., 2012), however, life table of B. dorsalis has not been studied in Vietnam.
1.3.3. Ecological characteristics
Population variation of B. dorsalis has been studied from 2009 to 2011 in
dragon fruit production area in Long An (Le Thi Dieu and Nguyen Van Huynh,
2009), Binh Thuan (Nguyen Thi Thanh Hien et. al., 2011) and Tien Giang (Viện
Nghiên cứu cây ăn quả miền Nam, 2011). Food, moisture and temperature were
reported to impact on the capture of B. dorsalis in pheromone traps in Tien Giang
and Binh Thuan. No result on population variation of B. dorsalis is available for
Northern part of Vietnam.
5
1.3.4. Control methods
Cultivation control method (field sanitary) and physical method (fruit
packaging, pheromone traps) have been trialed and recommended (Le Duc Khanh
et. al., 2008; Nguyen Van Chi et. al., 2010; Nguyen Minh Chau et. al., 2010;
Nguyen Thi Thanh Hien et. al., 2012).
IPM program for control of fruit flies has been successfully implemented in
dragon fruit plantation in Binh Thuan and Tien Giang (Nguyen Minh Chau et. al.,
2010; Nguyen Thi Thanh Hien et. al., 2012).
1.4. Conclusion and concerning issues
Oriental fruit flies have been extensively and systemically studied worldwide.
However, such studies on biological and ecological characteristics of B. dorsalis are still
limited, especially in the field study in Vietnam. Therefore, to meet the increasing
requirement for fruit production in Vietnam, it is necessary to have more comprehensive
studies on biology and ecology of B. dorsalis in Vietnam field conditions.
CHAPTER 2. MATERIAL, CONTENT AND METHOD
2.1. Study location: Study was conducted in Moc Chau district, Son La province.

2.2. Study duration: Study was conducted between 2009 and 2013.
2.3. Materials: Oriental fruit flies, common fruit trees and experimental materials
for collecting and rearing of the fruit flies.
2.4. Study content
- To determine species composition and damage of fruit flies on fruit trees
in some provinces in the North;
- To study biological characteristics of Oriental fruit flies B. dorsalis;
- To study ecological characteristics of Oriental fruit flies B. dorsalis;
- To develop an effective IPM control method of B. dorsalis in Moc Chau,
Son La province.
2.5. Methods
Study species composition and damage of fruit flies followed method
described by Drew et. al. (2001). Classification of fruit flies was based on
literatures from White and Harris (1992) and Lawson et. al. (2003).
Biological characteristics of fruit flies were studied following methods described by
Walker et. al. (1996), Vargas et. al. (1997) and Nguyen Van Dinh (1994).
Ecological characteristics, population dynamics and factors affecting population
dynamics of fruit flies were based on methods described by Drew et. al. (2001),
Walker et. al. (1996), Vargas et. al. (1997) and Nguyen Van Dinh (1994).
Field experiments for control of Oriental fruit flies B. dorsalis were
conducted in a complete randomized design with 3-4 replications.
Large scale experiment implementing IPM control program for control of
Oriental fruit fly B. dorsalis on local H’Mong peach was conducted in farmer
plantation with the control treatment as farmer’s practice.
2.6. Data analysis: Data were statistical analyzed based on method described by Vo Huy
Van et. al. (1997) and using IRRSTAT statistical analysis program (IRRSTAT 5.0).
6
CHAPTER 3. RESULTS AND DISCUSSION
3.1. Species composition and damage of fruit flies in some provinces in
Northern Vienam

3.1.1. Species composition and distribution
Survey using pheromone traps and collecting of damaged fruits from 4
provinces in the North of Vietnam has revealed 21 fruit fly species including 19
Bactrocera species and 2 Dacus species, Tephritidae family. Among these
determined fruit fly species, 11 Bactrocera species were common found in all
investigated locations in Hanoi, Son La, Hoa Binh and Lao Cai provinces. The
other 10 species were distributed individually in particular provinces.
3.1.2. Species composition and host plants
Study has recorded 31 host fruit species for fruit flies in 4 studied provinces
including Hanoi, Son La, Hoa Binh and Lao Cai. 22 fruit species out of 31
reported fruits were from fruit trees including 17 sub-tropical fruit tree species and
5 temperate fruit tree species. The rest was fruit vegetables and wild fruit trees.
B. correcta, B. carambolae, B. dorsalis, B. pyrifoliae and B. verbacifoliae were
found damaging fruit trees; B. cucurbitae, B. tau, B. latifrons caused damage on both fruit
vegetable and wild fruit trees. Oriental fruit fly B. dorsalis damaged on both cultivated
fruit trees including subtropical and temperate fruit tree species and wild types.
3.1.3. Fruit flies abundance and their host plants in Moc Chau, Son La
21 fruit fly species have been recorded in Moc Chau including 19
Bactrocera species and 2 Dacus species, Tephritidae family. Among these
determined fruit fly species, B. carambolae was also found on fruit trees in Moc
Chau, Son La.
31 fruit tree species were determined as host plants for fruit fly. Oriental
fruit fly has a most diverse host plants (20 species).
3.1.4. Feeding damage
In the field, fruit flies were active and damaged their host fruits from March to
November. They attached their hosts at different developmental stages of the fruit
depending on fruits tree species. Fruit trees were usually infested at ripen stage,
whereas fruit vegetables were infested starting at earlly fruit stage and all other later
stages. Fruit trees were more severe damaged than other host plants, i.e. fruit vegetable
and wild type. For instance, damage severities of fruit flies were 63.2%, 44,1% and

36.8% on local H’Mong peach, rose apple and kaki, respectively. Lower damage
severity was found on bitter gourd, the most severe damage among fruit vegetables,
accounting for 42% severity. The hosts for Oriental fruit flies included fruits of
Rosasae, Myrtaceae, Ebenaceae, Cucurbitaceae and Anacardiaceae families. Among
the host plants in Rosasae family, H’Mong peach was most severe damaged.
3.2. Biological charateristics of Oriental fruit fly B. dorsalis
3.2.1. Living behavior of B. dorsalis
Adult flies laied eggs deep into fruit flesh under the peel. Larvae fed and
developed inside fruit, caused fruit rotten and shed from tree. Matured larvae left
fruit and dropped into soil to pupate. Pupae were made at 2-3 cm underground.
7
3.2.2. Life cycle
Under rearing conditions on H’Mong peach at 28°C and RH 75% it took
1,98 ± 0,04 days for B. dorsalis eggs to hatch. Time for larvae to complete their
stage was 6,48 ± 0,04 days. Pupae needed 9,28 ± 0,09 days before emerging to
adults. Pro-oviposition adults lived for 14,79 ± 0,04 days before being ready for
laying eggs. The average life cycle of B. dorsalis was 32,53 ± 0,06 days. Males
can live for about 120 ± 3,8 days, while lifespan of females were about 140 ± 10,6
days (Table 3.4).
Table 3.4. Developmental stages and life cycle of B. dorsalis (Plant Protection
Research Institute- PPRI, 2012-2013)
Developmental stages Unit Time period n
Egg (*) day 1.98 ± 0.04 30
Larva (*) day 6.48 ± 0.04 30
Pupa (*) day 9.28 ± 0.09 30
Pre-ovipostional periods (*) day 14.79 ± 0.04 30
Life cycle day 32.53 ± 0.06 30
Lifespan of male (**) day 120 ± 3.8 19
Lifespan of female (**) day 140 ± 10.6 19
Note: (*) At temperature 28°C and RH 75%; (**) At temperature 26-28°C and RH 60-

75%, reared on H’Mong peach; n: sample size.
3.2.3. Reproductive behavior
3.2.3.1. Reproductive system: Oviduct of the female B. dorsalis consists of 3
movable segments. Male’s testes are at seminal vesicles and in pale yellow color.
Testes turn darker as males close to mature.
3.2.3.2. Sex ratio: Four out of six evaluations on sex ratio of B. dorsalis resulted in
higher ratio of females to males.
3.2.3.3. Ratio of female oviposition: Results from 3 laboratory experiments
showed that ratio of female B. dorsalis oviposition range from 91.7- 94.4 %
3.2.3.4. Day time preference for oviposition: Females prefered laying eggs from
13 to 16 p.m. (Figure 3.6).
0
20
40
60
80
100
120
Số trứng (quả)
9-12 giờ 13-16 giờ 16-19 giờ
Thời gian thu trứng trong ngày

Figure 3.6. Eggs production collected at different time period within a day in
laboratory conditions (PPRI, 2012)
Note: at temperature 26-28°C and RH 60-75%. n= 50
3.2.3.5. Female fecundity and frequency of oviposition: Oviposition behavior of B.
dorsalis was evaluated on 19 male and female couples in laboratory from July
8
2012 to January 2013 throughout their lifespan. Male and female adults were
separated and coupled right after emerging. Results showed that a female laid

average 6.68 eggs a day. Total number of eggs laid by a female varied
significantly from 574 to 1,298 eggs. In average, a female laid 949.73 eggs during
their lifespan (table 3.7). Egg production per female recorded in this study was
higher than that published by Nguyen Huu Dat and Bui Cong Hien (2004). These
authors reported an average egg production per female vary from 601-721 eggs.
Other authors reported more productive females laid 1,200-1,551 eggs in average
in their lifespan (Ian and Marlene, 1992; Pablo and James, 1996). This variation in
productivity of female Oriental fruit fly B. dorsalis can be explained by different
sources of B. dorsalis used for studies. Moreover, food sources also strongly
affected productivity of female B. dorsalis. This study performed on the 8
th

generation of laboratory B. dorsalis fed on H’Mong peach whereas Nguyen Huu
Dat and Bui Cong Hien (2004) studied the 3
rd
-4
th
laboratory generations fed on
carrot. Ian and Marlene (1992) also fed B. dorsalis with carrot, however the
productivity test was conducted on 65
th
laboratory generation of B. dorsalis.
Table 3.7. Average total oviposition time duration for a female and its
fecundity( PPRI, 2012-2013)
Observations
Range
Average
Total oviposition time period for a female
(day)
57 – 96 81.32 ± 2.8

Fecundity (Number of eggs/female/day 1- 46 6.68 ± 0.14
Total eggs laid/female
574-1298
949.7 ± 38,84

Note: Rearing condition at T=26-28°C and RH 60-75%, reared on H’Mong peach

Frequency of B. dorsalis female oviposition was also not continuously. This
study also observed “off-the job day” when female did not lay eggs (Figure 3.7).
0
5
10
15
20
25
30
35
1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103 109 115 121 127 133 139 145 151 157
Tuổi ruồi mẹ

Figure 3.7. Oviposition frequency of female B. dorsalis (PPRI, 2012-2013).

Note: Rearing condition at T=26-28°C and RH 60-75%, reared on H’Mong peach

3.2.4. Lower temperature threshold and generations in a year
B. dorsalis was reared at 2 temperature regimes, i.e. 23°C and 28°C, RH
75% and fed with H’Mong peach. Lower temperature threshold was calculated
9
based on life cycles determine at 2 studied temperature regimes. Lower
temperature threshold was determined at 10.2°C. Total effective degree day for B.

dorsalis to complete a generation was about 589.67 degree day. Hence,
theoretically, there were 6.0; 4.7 and 4.6 generations, on average in Moc Chau in
2010, 2011, and 2012, respectively.
3.2.5. Life tables
Under laboratory rearing conditions at 26 ± 2°C, and RH 60-80% B.
dorsalis fed on H’Mong peach has had high survival rate, relatively long female
lifespan and fecundity (Figure 3.8).
0
0.2
0.4
0.6
0.8
1
1.2
1 11 21 31 41 51 61 71 81 91 101 111 121 131 141
Ngày đẻ
0
2
4
6
8
Sức sinh sản (mx)
(con cái/ngày)
Tỷ lệ sống Sức sinh sản

Figure 3.8. Survival (lx) and fecundity (mx) of Oriental fruit fly B. dorsalis
(PPRI, 2012-2013).
Adult lifespan was longest at 162 days. Female started oviposition at day
21-21 after emerging. Some females can still laying eggs until 160 days after
emerging. Thus the lifetime for female oviposition was relatively long, accounting

for about 141 days calculated from the first to the last day of oviposition.
However, it was recorded that during the oviposition period there was some days
that female did not lay egg, hence the actual effective oviposition duration for B.
dorsalis in this study was about 81.32 ± 2.8 days. Highest fecundity of the females
was recorded at age of 26 to 85 days old. The fecundity decreased gradually from
day 90 after emerging. Female B. dorsalis usually ceased laying eggs at 1-3 days
before died.
Major biological parameters of B. dorsalis damaging on H’Mong peach was
calculated based on results of this study. Population developmental rate was
determined at r = 0.126 which means B. dorsalis individuals in a population
increase 12.6% over a period of 24 hours. Life cycle of a generation was 45.67
days based on lifecycle of females. Time for a population being double was
relatively short accounting for 5.63 days. This parameter implied that B. dorsalis
population will be double after 5-6 days. Population multiple factor (Ro) of a
generation was high (Ro = 325.65) mean every female individual can produce 325
female progenies. Population increasing limit λ = 1.135 implied that the number of
individuals in a population increased 1.135 times after 24 hours (Table 3.10).
10
Table 3.10. Some major biological parameters of B. dorsalis (PPRI, 2012-2013)
Parameter Value
The net reproductive rate Ro (
♀/generation)
325.65
Mean reproduction time T(days) 45.65
Life cycle of a generation Tc (days) 73.59
Doubling time DT (days) 5.63
Intrinsic rate of increase r (per days) 0.123
The finite rate of increase λ (per days) 1.131
Note: Rearing conditions at temperature 26 ± 2°C; RH 60 - 80%; day: night time
10:14hrs, fed on H’Mong peach.

3.2.6. Host range of B. dorsalis
From 2010 to 2012, 1,682 fruit samples with feeding evidence have been
collected from fruit trees, fruit vegetables and wild fruit plants in Moc Chau, Son
La province. 20 fruits was recorded as host for B. dorsalis including litchi, longan,
pomelo, star fruit, fig, mango, papaya, H’Mong peach, imported peach, stone fruit,
plum, sapote, custard apple, guava, rose apple, kaki, apple, …. in Moc Chau, Son
La province. This is the first study on host range of B. dorsalis in Moc Chau.
3.3. Ecological characteristics of B. dorsalis
3.3.1. Impact of temperature on developmental stages of B. dorsalis
Temperature had a strong impact on all developmental stages of B. dorsalis.
At laboratory rearing conditions at temperature 23°C, B. dorsalis developed
through egg, larval stage and pupal stage in 3.76, 11,3 and 13,7 days, respectively.
Life cycle of B. dorsalis at this temperature was 63.65 days. Females needed 17.46
days before copulated and oviposition. Shorter developmental times have been
recorded when reared B. dorsalis at 28°C. Times for egg, larval stage and pupal
stage were 1.98, 6.48 and 9.82 days, respectively. Likewise, shorter times were
also recorded for life cycle and pro-oviposition females accounting for 32.53 and
14.79 days respectively (Figure 3.9; 3.10; and 3.11).
0.00
20.00
40.00
60.00
80.00
100.00
Thời gian phát
triển (giờ)
23°C 28°C
Điều kiện nhiệt độ

Figure 3.9. Impact of temperature on
egg stage of B. dorsalis (PPRI, 2013)
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
Thời gian phát
triển (ngày)
23°C 28°C
Điều kiện nhiệt độ
Pha sâu non
Pha nhộng

0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
Thời gian phát
triển (ngày)

23°C 28°C
Điều kiện nhiệt độ
Trước đẻ trứng
Vòng đời

Figure 3.10. Impact of temperature on
larval and pupal stages of B. dorsalis
(PPRI, 2013)
Figure 3.11. Impact of temperature on
pre-oviposition female and life cycle
of B. dorsalis (PPRI, 2013)
11
3.3.2. Impact of food source on developmental stages of B. dorsalis
3.3.2.1. Impact of food on developmental stages of B. dorsalis: In this study, larvae
B. dorsalis were fed with different fruits including H’Mong peach (Prunus persica
L.), mango (Mangifera indica L.), guava (Psidium guajava L.), papaya (Carica
papaya L.) and carrot (Daucus carota subsp. sativus) to demonstrate the impact of
different food sources on the developmental stages and lifecycle of B. dorsalis.
Significant shorter in developmental time for egg stage of B. dorsalis eggs
manually placed on ground carrot, accounting for 1.8 days, compared to the eggs
on H’Mong peach, papaya, mango and guava, accounting for 3.76, 2.38, 2.49 and
2.59 days, respectively (p<0.05) (Table 3.12). Different moisture of the food,
where eggs were placed, was attributed to difference in incubation duration of
eggs. Ground carrot can keep better moisture. The incubation times of B. dorsalis
eggs in this study were still longer than that reported by Nguyen Huu Dat and Bui
Cong Hien (2004), Duong Minh Tu et. al. (2001), Vo Thi Bao Trang et al. (2012)
and Manoto and Tuazon (1992-1993).
Duration of the larval stage shortest on papaya, mango and carrot, ranged
from 9.04 to 9.83 days, whereas larval fed with guava and H’Mong peach longer,
10.66 days and 11.26 days respectively (table 3.12). Time for larval fed papaya

and mango was different in not significant, but also significant at H’Mong peach,
carrot and guava formulars (P< 0.05). Development duration of larval in this study
was prolong than that results of Nguyen Huu Dat and Bui Cong Hien (2004),
Duong Minh Tu và nnk. (2001), Vo Thi Bao Trang và nnk. (2012), Manoto and
Tuazon (1992-1993).
Table 3.12. Time duration of different developmental stages of B. dorsalis
on food sources (PPRI, 2012-2013)
Food
source
Time period for developmental stages (days)
Life cycle
(days)
Egg Larva Pupa
Female pre-
oviposition
Peach 3.76

c 11.26 d 13.67

b

17.46 d

46.15 d


Papaya 2.38 a 9.62 b 12.23

a

15.19 b 39.43 b
Carrot 1.84

a 9.04 a 11.84

a

14.00 a 36.73 a
Mango 2.49 a 9.83 b 12.33 a 13.85 a 38.51 b
Guava 2.59 b

10.66 c 15.30 c 16.20 c 44.75 c
LSD
0,05
0.71 0.37 0.68 0.47 1.24
CV (%) 1.5 2 2.9 1.7 1.7
Note: Mean in the same column followed by the same letter are not significantly
different (P< 0.05);Temperature: =23°C; RH =75%; n = 30
Similarly, pupae completed their development shortest on carrot, 11.84
days, whereas pupae collected from larvae fed with papaya formula , mango
formula , peach formula and guava formula prolonged their developmental
duration to 12.23, 12.33, 13.67 and 15.20 days (Table 3.12). Duong Minh Tu et.
12
al. (2001) also reported 11.5 days for pupae developed on carrot. However this
time periods were only 7-8 days as reported by Nguyen Huu Dat and Bui Cong
Hien (2004), and Manoto and Tuazon (1992).
Significant difference was also found in the pre-oviposition stage of female
before laying eggs, which varied from 13.85 days for larvae fed on mango to
17.46 days for that fed on H’Mong peach (p<0.05). Life cycle of B. dorsalis was
also significantly different on different food sources. Longest life cycle was

recorded on H’Mong peach (46.15 days), while shortest life cycle was recorded on
larvae fed on carrot (36.73 days) (Table 3.12). Life cycle of B. dorsalis in this
study is as long as about 1.5 times that reported by Jayanthi (2002), and Nguyen
Huu Dat and Bui Cong Hien (2004) which accounts for 18.5-26.5 days.
3.3.2.2. Impact of larval diet on sex ratio and female fecundity: Larva fed on
papaya and carrot resulted in more female adults than males, sex ratios in these
cases were 0,9:1 and 0,77: 1 male: female. On the contrary, more males were
found on larva population fed on peach, mango and guava. The sex ratios (male:
female) were calculated at 1.3:1 on peach; 1.05:1 on mango; and 1.3:1 on guava.
Results of this study supports others studies on the effects of larval diet on the sex
ratios (Jayanthi, 2002; Khan et. al., 2011).
Relatively high percentage of females oviposited and this percentage was
also larval diet dependent. 78.33% females from larvae fed on mango were
oviposited, this number was 84.44% for females from guava and carrot. However,
differences in percentage of female oviposited were not statistically significant
(p<0.05) (Table 3.13).
Table 3.13. Impact of diet on percentage of female B. dorsalis oviposition
(PPRI, 2012-2013)
Larval food
source
Percentage (%) of females oviposited
Maximum Minimum Average
Peach 88.33 80.00 83.89 ± 2.42 a
Papaya 90.00 76.67 83.33 ± 3.85 a
Carrot 88.33 80.00 84.44 ± 2.42 a
Mango 86.67 75.00 78.33± 4.19 a
Guava 85.00 80.00 83.33 ± 1.67 a
LSD
0,05
= 0.13 CV (%) = 6.1

Note: Within a column, similar letters denote not significant difference at α = 0,05;
Percent (%) values were conversed to arsine before statistical analysing.
Study conditions: t
o
=23
°
C; RH = 75%; n = 60

Higher female fecundity was recorded on larval population fed on carrot and
guava. Female fecundity was 67.2 eggs/female on carrot diet and 64.38
eggs/female on guava. Lowest female fecundity was found on H’Mong peach
(48.08 eggs/female) (Table 3.14).
13
Table 3.14. Impact of larval diet on female fecundity of B. dorsalis (PPRI,
2012-2013)
Larval food source
Female fecundity (eggs/ ♀) (*)
Range Average
Peach 46.2 - 50.4 48.08 ± 1.25 a
Papaya 49.6 - 55.3 52.04 ± 1.68 a
Carrot 63.1 - 70.1 67.20 ± 2.19 b
Mango 49.6 - 56.0 52.30± 1.92 a
Guava 60.6 - 68.7 64.38 ± 2.34 b
LSD
0.05
= 5.9 CV (%) = 5.8
Note: Within a column, similar letters denote not significant difference at α =5%; Study
condtions: t
o
=23

°
C; RH = 75%; (*) Denote data was recorded continuously from the
starting date of female oviposition.
Adult lifespans were also larval diet dependent. Shortest lifespan was
recorded on larvae fed on papaya (126 days), while longest lifespan was on
H’Mong peach (130.2 days). Lifespans on mango, carrot and guava were 127.8,
128.7 and 126.3 days, resp. (Figure 3.14.).
123
124
125
126
127
128
129
130
131
Đào đu đủ Cà rốt Xoài Ổi
Thức ăn sâu non
Ngày

Figure 3.14. Impact of larval diets on adult lifespan of B. dorsalis (PPRI, 2012-2013)
3.3.2.3. Impact of larval diet on pupal weight: Pupal weight was also strongly
affected by larval diet. Pupal weight was measured at 18.3, 16.1, 14.8 and 15.9 mg
on carrot, guava, papaya and mango, respectively. Smallest pupae were found on
H’Mong peach (13.4 mg) (Table 3.15).
Table 3.15. Impact of larval diet on pupal weight of B. dorsalis (PPRI, 2012-2013)
Larval food
source
Pupal weight
Weight of 100 pupae (gram) Weight of 1 pupae (mg)

Peach 1.34 ± 0.0007 d 13.4
Papaya 1.48 ± 0.0004 c 14.8
Carrot 1.83 ± 0.0123 a 18.3
Mango 1.59 ± 0.0002 bc 15.9
Guava 1.61 ± 1.11 b 16.1
LSD
0.05
= 0.11 CV (%) = 4.0
Note: Within a column, similar letters denote not significant difference at α =5%; Study
conidtions: t
o
=23
°
C; RH = 75%;
3.3.2.4. Impact of larval diet on stage completion of B. dorsalis: Most effective
stage completion of B. dorsalis was recorded on carrot diet. Highest egg hatch
14
percent was found on carrot (88.9%), followed by that on H’Mong peach (81.11%),
papaya and guava (72.22%) and mango (68.89%). Likewise, highest percentage of
larvae completed their stages was recorded on carrot (87.78%). White on papaya,
H’Mong peach, guava and mango these were 82.22%, 80%, 70% and 66%,
respectively. More pupae reared on carrot were emerged to adults (93.33%) than on
other food, e.g. mango, papaya and H’Mong peach (90%) (Table 3.16).
Table 3.16. Percent stage completion of B. dorsalis (PPRI, 2012-2013)
Larval food
source
Percent stage completion (%)
Egg
Larva
Pupa

Peach
81,11 ab
80,00 bc
90,00 a
Papaya
72,22 bc
82,22 ab


90,00 a


Carrot
88,89 a
87,78 a
93,33 a
Mango
68,89 c
69,78 bc
90,00 a
Guava
72,22 bc
65,55 cd
92,22 a
LSD
0.05

0.58
0.16
0.1

CV (%)
2.9
7.8
4.5
Note: Within a column, similar letters denote not significant difference at α = 0,05;
Percent (%) values were conversed to arsine before statistical analysing.
Study conditions: t
o
=23
°
C; RH = 75%; n = 30
3.3.3. Development and factors impact on development and growth of B.
dorsalis in Moc Chau, Son La.
3.3.3.1. Development and population dynamic of adult B. dorsalis: None of B.
dorsalis was captured in pheromone traps during January and March in Moc Chau,
Son La. The first capture was recorded on the last week of April and May. The
number of B. dorsalis in traps increased rapidly in mid- May and peaked on the
last week of June to first week of July. Thereafter, the number of captured adults
reduced gradually until August, and vanished in November and December (Figure
3.15). This result supported other studies on biology of B. dorsalis. In conclusion,
the first generation of B. dorsalis occurred in late April in Moc Chau, Son La.
There was overlapped in B. dorsalis generations due to prolong lifespan and
oviposition duration of the adults.
0
10
20
30
40
50
60

T
1
T

3
T

5
T

7
T

9
T

1
1
T

1
T

3
T

5
T

7

T

9
T

1
1
T

1
T

3
T

5
T

7
T

9
T

1
1
Tháng
Số ruồi
(con/bẫy)

Figure 3.15. Population dynamic of B. dorsalis captured in pheromone traps
in Moc Chau, Son La province in 2010, 2011 and 2012.
3.3.3.2. Impact of some ecological factors on population development of B.
dorsalis in Moc Chau, Son La
15
* Weather conditions : The ambient humidity was recorded at 3 specific
times of the year, i.e. during 3 months with absence of B. dorsalis, before and right
at the first capture of B. dorsalis in the traps. In two years 2010 and 2011, the
ambient humidity during the first captures of B. dorsalis was 94%. B. dorsalis was
captured in traps in 2010 earlier than in 2011. Humidity during the absence and
right before capture of B. dorsalis in 2011 was higher compare to the exact same
time in 2010. The first capture of B. dorsalis in 2010 was earlier than in 2011. In
2011 and 2012, the ambient humidity before capture of B. dorsalis was equivalent.
However, humidity at the first capture was lower in 2012 (RH 52%) compare to
2011 (RH 94%). Earlier capture of B. dorsalis was also recorded in 2012 compare
to 2011. In conclusion, there seemed a correlation between lower humidity of the
3 evaluated time points and the first capture of B. dorsalis or B. dorsalis was
captured earlier in pheromone traps if humidity of each evaluated time point of
that year felt lower (drier) than at the same time of other years.
Table 3.17. Ambient air humidity and temperature and the first capture of B.
dorsalis in pheromone traps in Moc Chau, Son La in 2010, 2011, 2013


Year
Time points
Time of the first
capture
I* II III
t
o

(°C)

RH
(%)
t
o

(°C)
RH
(%)
t
o

(°C)
RH
(%)
2010 16.7 81.6 19.2 83.3 20.1 94.0 April 26
th
2010
2011 11.4 89.0 16.2 86.0 20.5 94.0 April 29
h
2011
2012 11.4 89.8 19.1 86.0 26.9 52.0 April 25
th
2012
Note: * I: 3 months during the absence of B. dorsalis (December, January and
February); II: during 46 days before the capture (based on results in Table 3.11); III: at
the first capture
There was a quite difference in average temperature (6.8°C) at the first
captures of B. dorsalis in 2010 and 2012. However, first captures were recorded at

almost the same time of the year (April 26
th
2010 and April 25
th
2012). Hence, it
was concluded that temperature has had no effect on the occurrence of B. dorsalis.
Temperature during 46 days to the first capture was similar for 2010 and 2012
accounting for 19.2 and 19.1°C, resp. whereas lower temperature was recorded at
the same time point in 2011 (16.2 °C) (Table 3.17). Thus, average temperature
during 46 days to the first capture (time for a generation based on a female life
cycle) had impacted on the occurrence of B. dorsalis, the lower the temperature at
this time, the later occurrence of B. dorsalis.
The number of B. dorsalis generations in Moc Chau, Son La was not constant
over years. 6.01 generations were recorded in 2010, whereas this number in 2011
and 2012 was 4.71 and 4.56, resp Temperature was also found to play its role in
the number of B. dorsalis generations occur in a year (for detail see section 3.2.4).
No correlation was found between temperature and population development
of B. dorsalis in Hoa Loc mango plantation in Tien Giang (Southern research
16
institute for fruit tree, 2013). However, a positive correlation, though not so
strong, (R= 0,83; R² = 0,697; t= 4,2; P< 0,05), was found between temperature and
the number of B. dorsalis captured in pheromone traps.
Optimal temperature for B. dorsalis was at 20°C to 28°C. A female B.
dorsalis can lay about 1,581 eggs at 22°C (Wu et. al., 2000; Yang et. al., 1994).
Temperature in Moc Chau, Son La from April to September in 2010-2012 ranged
from 19-25°C, which was very favour conditions for development and growth of
B. dorsalis. However, the number of individuals captured in traps during this time
period varied greatly. In conclusion, temperature only impacted on the occurrence
of B. dorsalis but not its population abundance in fruit plantations in Moc Chau,
Son La province.

3.3.3.3. Host plant availability: In Moc Chau, host fruit trees are fruited and ripen
from May to September leading to significant increase in the population of B.
dorsalis. The first peak of B. dorsalis populations was recorded in late June, the
same ripen time for plum, H’Mong peach, litchi and mango. Second peak was
recorded in mid September, ripen time for kaki (Figure 3.16).


H’Mong
peach
early

Stone
fruit Plum Mango Litchi

Custard
apple Kaki


1 2

3

4

5

6 7 8

9

10

11

12


Month
Figure 3.16. Ripen season of host plants and population dynamic of B.
dorsalis captured in pheromone traps in Moc Chau, Son La province.
Check random fruit samples in the middle of harvesting season showed that
highest damage was found on peach (42%) followed by Nhan Hau persimon
(36.8%), seedless persimon (35.5%), mango (25%) and plum (17.6%). In Moc
Chau, areas for mango and plum plantations are larger than that for peach and
kaki. Average number of adults emerged from a H’Mong peach fruit was 6.6
adults/fruit as 2.6 times of that from a mango fruit (2.47 adults/fruit), 3.1 times of
adults from Nhan Hau persimon (2.09 adults/fruit) and 3-6 times of adults from
seedless persimon and plum (1-2 adults/fruit) (Figure 3.17). Thus percentage of
fruit damage and the number of adults B. dorsalis emerged from a single host fruit
depended on host preference. Similar results were also reported for B. dorsalis on
papaya and rambutan in Hawaii (Clarke et. al., 2005). In this study, 55% of
papaya fruits were infested with B. dorsalis, while only 0.026% rambutan fruits
were damaged.
17
6.58
2.09
1.91
2.47
1.76
42%

36.8%
35.5%
25%
17.6%
Đào Mèo
Hồng nhân hậu
Hồng không hạt
Xoài
Mận
TT/quả TLH%

Figure 3.17. The number of adults B. dorsalis emerged from a single fruits of
different hosts in Moc Chau, Son La province, 2012
Therefore, for such damage behavior of B. dorsalis and fruit production in
Moc Chau, the possibility for population development of Oriental fruit fly was
mainly results of damaging factors of H’Mong peach and Tam Hoa plum
consisting of percentage of infested fruits and damage severity of each fruit (the
number of adults emerged from an infested fruit). Ripen season for H’Mong peach
was the major reason caused population outbreak of B. dorsalis in Moc Chau.
Similar conclusion was also stated in studies from Le Thi Dieu and Nguyen Van
Huynh (2009) in Long An, Nguyen Thi Thanh Hien et. al. (2012) in Binh Thuan,
Frank et. al. (1970) in Hawaii, Keawchoung et. al. (2000) in Thailand, and
Muhammad (2002) in Pakistan.
Population dynamic of B. dorsalis was also studied in the mixed fruit tree
plantation including plum, peach, custard apple, kaki, mango, and local apple in
Co Do and Long Luong communes in Moc Chau from 2011 to 2013. Results
showed a difference in population dynamics of B. dorsalis captured in pheromone
traps (Figure 3.18). In Long Luong, in all three studied years, the B. dorsalis was
first captured in late April with a very low density (0.2 adult/trap). The number of
B. dorsalis in traps increased from mid May (1-3 adults/trap on May 5-10

th
) to late
May (4-7 adults/trap on May 28
th
). The capture of B. dorsalis peaked in July (49.4
adults/trap), thereafter, captured populations decreased gradually and none adult
was captured in traps in October. Higher B. dorsalis density was reported in Long
Luong than in Co Do location in traps during the peak time in June and July
(Figure 3.18).
0
10
20
30
40
50
60
70
T
1
T

3
T

5
T

7
T

9
T

1
1
T

1
T

3
T

5
T

7
T

9
T

1
1
T

1
T

3

T

5
T

7
T

9
T

1
1
Tháng
Số ruồi (con/bẫy)
Luóng luông Cờ đỏ

Figure 3.18. Population dynamics of B. dorsalis captured in pheromone traps
in Long Luong and Co Do locations in Moc Chau from 2010 to 2012.
18
In Co do location, the first capture was also in late April, however the
captured density was much higher than that in Long Luong location (4.7
adults/trap vs. 1.8 adults/trap in Long Luong). Two population peaks in Co Do
location were determined in Co Do location during April-May and August-
October (Figure 3.18).
Different population dynamics in two studied locations were perhaps the
results of the availability of preferred host fruits. Long Luong location is well-
known for a large peach plantation area with a very limited alternative hosts.
Hence, in April when peach fruits were still young, limited alternative hosts did
not trigger population development of B. dorsalis compared to Co Do location. In

May, peach started ripen, however at this time B. dorsalis density was still low
since the started population in late April need about 32.53 days to complete their
life cycle (see Table 3.4). Hence in June when the first generation completed their
life cycle, and peaches were ripen led to the peak of B. dorsalis population.
Average number of adult emerged was about 6.6 adults/fruit. After harvesting of
peach, population felt due to shortage of alternative hosts (Figure 3.19). According
to Pham Binh Quyen (2006) insects possess population regulation mechanism,
individuals migrate to look for food. Hence in the shortage of available food
source in Long Luong after peach season, B. dorsalis population can migrate to
other places leading to population reduced (Figure 3.19).





ĐM
, M










ĐCS

0
10
20
30
40
50
60
70
I II III IV V VI VII VIII IX X XI XII
Thời gian
trong năm
Số lượng ruồi
(con/bẫy)
Năm 2010 Năm 2011 Năm 2012

Figure 3.19. Population dynamic of B. dorsalis in pheromone traps in Long
Luong, Moc Chau from 2010 to 2012.
Note: DM: H’Mong peach; M: plum; DCS: early ripen peach
In Co Do location, H’Mong peach planting area is small and planted

scattered, hence even in the middle of peach season, much lower population of
B. dorsalis was recorded in this location compared to Long Luong location
(Figure 3.20).
19










Persimon












Custant
apple

Lichii














Mango

H’Mong
Peach











DCS
Plum

0
10
20
30
40
50
I II III IV V VI VII VIII IX X XI XII
Thời gian
trong năm
Số lượng ruồi
(con/bẫy)
Năm 2010 Năm 2011 Năm 2012

Figure 3.20. Population dynamic of B. dorsalis in pheromone traps in Co Do,
Moc Chau from 2010 to 2012.
Note: DCS: early ripen peach
As reported, B. dorsalis densities in traps in April, May, August, September
and October in Co Do location were always higher than that in Long Luong
location during three studied years (Figure 3.21). These months were ripen season
for other hosts of B. dorsalis such as earlier ripen peach, plum, litchi,
persimon…This supported the conclusion of closed interaction between diversity
of host ranges and population dynamic of B. dorsalis.
0

10
20
30
40
50
60
I II III IV V VI VII VIII IX X XI XII
Thời gian trong năm
Số lượng
(con/bẫy)
Xã Lóng Luông Tiểu khu Cờ Đỏ

Figure 3.21. Average number of B. dorsalis in pheromone traps in Long
Luong and Co Do locations in Moc Chau, Son La province in 2010-2012.
In conclusion, host range had a strong impact on population dynamic of B.
dorsalis. Population dynamics of B. dorsalis in the H’Mong peach plantations
were clearer and simpler than in the mixed fruit tree plantations. In both studied
locations, ripen season of H’Mong peach showed its important role in population
dynamic of B. dorsalis in Moc Chau, Son La province. This result supported other
studies population dynamic of B. dorsalis on other host plants (Le Thi Dieu and
20
Nguyen Van Huynh, 2009; Nguyen Thi Thanh Hien et. al., 2012; Vargas et. al.,
1990; Amice and Sales, 1996; Ye and Jian, 2005).
3.3.3.4. Natural enemies: Peaches samples were collected from plantations in Moc
Chau, Son La province 24 times during 2011 and 2012 to observe natural enemies
of B. dorsalis. However, parasitic wasps were only recorded in 4 samples
(frequency 16.7%) collected in the late seasons, but none of predator was found in
the samples. Hence, natural enemies seemed having no effect on population
abundance of B. dorsalis.
3.4. Integrated pest management program for of B. dorsalis in Moc Chau, Son

La province
Biological and ecological characteristics of B. dorsalis showed that this fruit
fly species has a high fecundity, quick population development, wide range of hosts.
In Moc Chau, Son La province, B. dorsalis appeared in late April, and peaked in 45-
50 days later at the ripening season of H’Mong peach. B. dorsalis population strongly
depended on population development in May. Hence, for the success management of
B. dorsalis in Moc Chau, it is necessary to have effective control program to the
whole fruit plantation areas right at the beginning of population development to
prevent B. dorsalis from migration and population accumulation. IPM program for B.
dorsalis was conducted in Long Luong commune where has as large peach plantation
area as half of fruit tree plantation area in Moc Chau.
3.4.1. Determination critical time points for implementation of control methods
Results of several year damage investigation showed that B. dorsalis started
infesting in later stage of fruiting when peel changes from green to yellow.
Infested severity increased as increasing of ripening of peaches. Infested severity
varied significantly depend on the ripening of collected samples over the years
2007, 2008, 2009 and 2011 (p<0.05). Infested rate at green-yellow fruit stage
ranged from 1.7 to 5.3% (treatment 2). The infested rate increased to 22.7-48.3%
when fruits turned yellow (treatment 3), and 34.0-72.7% when fruits turned pale
pink (treatment 4) and so on (Table 3.19).
Table 3.19. Infested rate of B. dorsalis in H’Mong peach at different ripen
stages in Moc Chau, Son La, 2007-2011.
Year
Infested rate (%) in treatment

Statistic
1
2
3
4

5
6
2007

0 f 4.0 e

46.0 d

71.0 bc

79.0 bc

86.7 a

LSD
0.05
= 12.35
CV% = 14.5
2008

0 d 5.3 c

35.3 b


68.0 ab

77.0 a

82.3 a

LSD
0.05
= 13.7
CV% = 17.3
2009

0 e 2.7 d

48.3 c


72.7 ab


73.3 ab


84.7 a

LSD
0.05
= 16.1
CV% = 19.3
2011

0 e

1.7 d

22.7 c

34.0 c

57.3 a

69.0 a

LSD
0.05
= 11.5
CV% = 20.9
Note: Treatment 1: Green peach; Treatment 2: Green-yellow peach; Treatment 3:
Yellow peach; Treatment 4: yellow-pale pink peach; Treatment 5: pink peach;
Treatment 6: pink-red peach
21
Adults B. dorsalis were already captured in traps at young stage of peach,
however none damage was recorded on fruit. Later, the number of B. dorsalis
captured in traps increased rapidly, likewise damage rate also increased
significantly on fruits. In 2011, the number of adults in traps increased from 4
adults/trap during green peach, to 9 adults/trap during green-yellow peach, to 15
adults/trap during yellow peach and to 74 adults/trap during pink-red peach on
pheromone traps were collected weekly. Fruit damage rates also increased rapidly
from 9% at green-yellow peach to 11%, 15% in later ripen stages of peaches to
62% when peach turned pink. Similar results were also recorded in 2012 (Figure
3.22). In conclusion, B. dorsalis started infesting H’Mong peach when fruits start
changing to green-yellow. Infested rates increased significantly as ripening of the
fruits. Changing color of peach signaled starting of physical ripening stage. This is
the sensitive stage of peach to B. dorsalis, hence this is also critical time for any

control methods.
0
20
40
60
80
100
120
vỏ xanh vỏ xanh vỏ xanh vỏ xanh vỏ xanh vỏ xanh
vàng
vỏ xanh
vàng
vỏ hồng vỏ hồng vỏ đỏ
hồng
vỏ đỏ
hồng
Màu vỏ quả
Con/bẫy
0
10
20
30
40
50
60
70
80
TLH (%)
Ruồi/bẫy năm 2010 Ruồi/bẫy năm 2011
Ruồi/ bẫy năm 2012

TLH % 2010 TLH % 2011 TLH % 2012

Figure 3.22. The number of adults B. dorsalis in traps and infested rate in
H’Mong peach in Moc Chau, Son La in 2001-2012

3.4.2. Implementation of large scale IPM program for B. dorsalis in Moc
Chau, Son La
Studies on control methods for B. dorsalis were conducted in Long Luong,
Moc Chau from 2010-2012. Treatments consisted of 1) food - protein bait mixed
traps to lure and kill adults; 2) pheromone traps plus spray protein bait to attract
and kill adults once fruits change to green-yellow color; and 3) control without
any insecticide application. All treatments were implemented together with field
sanitary to clean and bury fruits felt on ground. All treatments were conducted in 5
Ha plantations except for the control (1 Ha).
Significant difference was recorded for the number of adults/trap between
treatments in 2010. In the control treatment, the number of adults was less than 4
adults/trap/day at the beginning of peach season, then peaked to 5.7
adults/trap/day on June 16
th
, and decreased to 2.1 adults/trap/day at the end of the
peach season (July 9
th
). Lower number of B. dorsalis was trapped in treatment 1
and 2 compared to control. Treatment 2 trapped more B. dorsalis than in treatment
1. Number of adults in trap in first treatment varied from 0.57-2 adults/trap/day, in
second treatment varied from 0.3-2.2 adults/trap/day (Figure 3.23).
22
0
1
2

3
4
5
6
12/4 19/4 26/4 3/5 10/5 17/5 24/5 2/6 9/6 16/6 24/6 2/7 9/7
Ngày điều tra (năm 2010)
Công thức 1
Công thức 2
Công thức 3

0
2
4
6
8
10
12
1
6
/
4
2
3
/
4
3
0
/
4
7

/
5
1
4
/
5
2
1
/
5
2
8
/
5
5
/
6
1
2
/
6
2
0
/
6
2
8
/
6
5

/
7
1
4
/
7
Ngày điều tra (năm 2011)
Số ruồi/bẫy/ngày
Công thức 1
Công thức 2
Công thức 3

0
2
4
6
8
10
12
1
2
/
4
2
8
/
4
1
5
/

5
2
8
/
5
1
4
/
6
2
8
/
6
1
2
/
7
Ngày điều tra (năm 2012)
Số ruồi
/bẫy/ngày
Công thức 1
Công thức 2
Công thức 3

Figure 3.23. The number
of adults B. dorsalis in
traps in 2010 in Moc
Chau, Son La
Figure 3.24. The number
of adults B. dorsalis in

traps in 2011 in Moc
Chau, Son La
Figure 3.25. The number
of adults B. dorsalis in
traps in 2012 in Moc
Chau, Son La
Note: Treatment 1: food – protein mixed traps plus field sanitary
Treatment 2: pheromone traps plus spray protein bait plus field sanitary
Treatment 3: control without any insecticide application
Similar results were recorded in experiment in 2011. Highest number of
adults was recorded in the control treatment, which varied from 0.4-10.6
adults/trap/day. Peak capture of adults in this treatment was 10.6 adults/trap/day
on July 5
th
. Similar number of adults was captured in traps of treatments 1 and 2,
accounting for 0.1-1.3 adult/trap/day (peak on July 17
th
) for treatment 1, and 0.3-2
adults/trap/day (peak on July 14
th
) (Figure 3.24).
Likewise, in 2012, highest number of B. dorsalis was also captured in traps
of treatment 3, accounting for 4 adults/trap/day at the early season, and increased
to peak 11.3 adults/trap/day on July 12
th
. The trapped adults reduced rapidly at the
end of the peach season to 2.2 adults/trap/day. The number of trapped adults in
treatment 1 and 2 peaked at 3.4 adults/trap/day (on July 12
th
) and 3.6

adults/trap/day (on July 5
th
), resp. (Figure 3.25).
Infested rate on H’Mong peach increased gradually from the beginning to
the end of peach season and peaked to 11% in control treatment in 2010. Infested
rates were lower in treatment 1 and 2, accounting for 4 and 5%, resp. (Table 3.26).
0
2
4
6
8
10
12
26/4 3/5 10/5 17/5
Ngày điều tra
Tỷ lệ hại (%)
Công thức 1
Công thức 2
Công thức 3

Figure 3.26. Infested rate of H’Mong peach with B. dorsalis in 2010 in Moc
Chau, Son La
Note: Treatment 1: food – protein bait mixed traps plus field sanitary; Treatment 2:
pheromone traps plus spotted spray protein bait plus field sanitary; Treatment 3: control
without any insecticide application
23
In 2011, infested rate in control treatment increased from 1% (early season) to
peaked at 62% (late season). Much lower infestation was recorded in treatment 1 and
2, accounting for 5 and 7%, resp., at highest infestation (Figure 3.27).
0

10
20
30
40
50
60
70
7/5 14/5 21/5 28/5 5/6 12/6 20/6 28/6 5/7
Ngày điều tra
Tỷ lệ hại (%)
Công thức 1
Công thức 2
Công thức 3

0
20
40
60
80
100
15/5 23/5 28/5 6/6 14/6 21/6 28/6 5/7 12/7
Ngày điều tra
Tỷ lệ hại (%)
Công thức 1
Công thức 2
Công thức 3

Figure 3.27. Infested rate of H’Mong
peach with B. dorsalis in 2011 in Moc
Chau, Son La

Figure 3.28. Infested rate of
H’Mong peach with B. dorsalis in
2012 in Moc Chau, Son La
Note: Treatment 1: food – protein bait mixed plus field sanitary; Treatment 2:
pheromone traps plus spray protein bait plus field sanitary; Treatment 3: control
without any insecticide application

Similarly, infested rate in control treatment increased from 1% (early
season) and peaked at 77% (late season) in 2012. On the contrary, highest
infestation was only 5 and 7% for treatment 1 and 2, resp. (Figure 3.28).
Overall, total number of B. dorsalis trapped in control treatment accounted
for 60.88% total number of B. dorsalis captured in all three treatments during
three studied years. These percentages in treatment 1 and 2 were 17.07% and
22.05%, resp.
The different captures in different treatments proved that treatment methods
have effectively controlled of B. dorsalis population. Placement of food-protein bait
mixed traps provided best control method population in early peach season, leading
to less population abundance in this treatment compared to treatment 2 and control.
However, no big difference in the captures between treatment 1 and 2 showed that
under high density of B. dorsalis additional protein bait application to traps was
necessary for effective control of B. dorsalis.
In conclusion, integration of different control methods consisting of
pheromone traps, food traps, protein bait application and field sanitary (large scale
integrated pest management method) controlled effectively population abundance
and development of B. dorsalis leading to little damage in the plantation. Mutual
interaction of different control methods resulted in effective control of population
development of B. dorsalis, that is: field sanitary, collecting and destroying of
fruits on ground directly removed in field adult sources; pheromone traps provided
forecasting for occurrence of adults B. dorsalis and determined timing for protein
bait application; food traps lured and killed adults. Critical timing for application

of protein bait was defined at the beginning of physical ripening of H’Mong
peach, fruits turned green – yellow, or at the capture density of 5-10
adults/trap/day.