Nghiên cứu tính kháng thuốc bảo vệ thực vật của nhện đỏ nâu oligonychus coffeae nietner (acarina tetranychidae) trên cây chè và biện pháp khắc phục ở miền núi phía bắc việt nam tt tiếng anh

MINISTRY OF EDUCATION

MINISTRY OF AGRICULTURE

AND TRAINING

AND RURAL DEVELOPMENT

VIETNAM ACADEMY OF AGRICULTURAL SCIENCES
****************************

NGUYEN MINH DUC

STUDY ON ACARICIDES RESISTANCE OF THE RED SPIDER MITE
Oligonychus coffeae Nietner (Acarina: Tetranychidae) ON TEA AND THEIR
MANAGEMENT IN THE NORTHERN MOUNTAINOUS AREA OF
VIETNAM

Specialization: Plant protection
Specialization code: 962 01 12

SUMMARY OF AGRICULTURAL DOCTORATE THESIS

HANOI – 2019


The thesis was completed at: Vietnam Academy of Agricultural Sciences
Supervisors: 1. Ass. Prof. Dr. Le Van Trinh
2. Dr. Nguyen Thi Nhung

Peer reviewer 1:

Peer reviewer 2:

Peer reviewer 3:

The thesis will be defended for the doctoral degree of PhD and evaluated by defense
committee at Vietnam Academy of Agricultural Sciences

At ….. hour, day….. month ….. year 2019

This thesis can be accessed at:
1. Vietnam National Library
2. Library of Vietnam Academy of Agricultural Sciences
3. Library of Plant Protection Research Institute


1

INTRODUCTION
1. Urgency of the thesis
Red spider mite (Oligonychus coffeae Nietner) is a popular insect which caused
yield and quality lost on tea. Nowaday, insecticides have been used as the first choice of
tea growers. There was number of insecticides which used to have high effective in
controlling red spider mite, however, their effectiveness has reduced rapidly recently.
The determination of insecticide utilization’s status and the evaluation of resitance ability
of red spider mite are the basic for constructing effective management of resistance.
Consequently, the research namely “Study on acaricides resistance of red spider mite
Oligonychus coffeae Nietner (Acarina: Tetranychidae) on tea and their management in
the northern mountainous area of Vietnam” has been conducted because of its urgency.
2. Objectives and requirement of the thesis

2.1. Objective: To determine resistance level and formation rate of resistance of red
spider mite against common groups of insecticide. Based on results of the research,
propose some solutions to manage resistance of red spider mite in tea cultivated area in
the northern mountainous region of Vietnam.
2.2. Requirement
To evaluate actual situation of pesticide utilisation in controlling insect pests in
general and red spider mite in particular on tea in Thai Nguyen province and Phu Tho
province.
To determine resistance level and formation rate of resistance of red spider mite
against popular chemical acaricides that used to manage red spider mite in tea cultivated
area in Thai Nguyen province and Phu Tho province.
To evaluate effectiveness of intergrated red spider mite management based on the
rational use of pesticides.
3. The scientific and practical significance of the thesis
3.1. The scientific significancen of the thesis: Providing information, latest update of
scientific references on the extent of damage, resistant index and formation rate of resistance
groups of pesticides which have been using popularly to control pests in Thai Nguyen province
and Phu Tho province.
3.2. The practical significance of the thesis: The result of this research is to determine
scientific basis in construction of resistance management solutions against red spider mite in
IPM on tea contributing to safe and sustainable utilization of pesticides in tea production.
4. Object and scope of the thesis
4.1. Object of the thesis:Resistance of red spider mite (O. coffeae Nietner) on tea.
4.2. Scope of the thesis: The research focuses on evaluatation of pesticide utilization
state on tea in Thai Nguyen province and Phu Tho province. Susceptibility level and
resistance formation rate of red spider mite against some groups of chemical and
solutions for reduction in chemical resistance in Thai Nguyen province are researched as
well.
5. New research findings of the thesis:
The research firstly provides scientific references in a systematic way the resistance

2

level and resistance formation rate of red spider mite against 11 active ingredients (Abamectin,
Azadirachtin, Dimethoate, Emamectin benzoate, Fenpyroximate, Fenpropathin, Hexythiazox,
Matrine, Propargite, Pyridaben, Rotenone) which have been using popularly in controlling
pests on tea in mountainous region of northen Vietnam. Adding some references on the
efficacy of technical measures to restric the development of red spider mite and propose
resistance management of red spider mite as well.
6. Thesis structure: The thesis has 119 pages includes introduction, content (3
chapters), conclusion and suggestion with 36 tables, 7 figures. The references has 125
individuals with 41 Vietnamese references, 82 English references and 2 references
downloaded on the Internet.
CHAPTER I
SCIENTIFIC BASIS AND LITERATURE REVIEWS
1.1. Scienfific basis
The utilization of pesticides on tea are not the same in different countries lead to
the variation in rresistance formation in tea plantation area. Resistance management
solutions of red spider mite are also different. Consequently, research on insecticide
resistance of red spider mite is needed to conduct in particular condition.
1.2. Oversea studies
1.2.1. Biological, ecological characteristics and development regulation of red spider
mite
In South India, under laboratory condition with the average temparature is 25±2oC,
relative humidity is 85±5% and on UPASI-10 variety, the average duration from 1st
instar to 3 instar was 8.10±1.65 days. Lifespan of male and female adults are 12.60±2.15
days and 24.20±3.50 days in average, respectively. Gender ratio was 1:2.25
(male:female). Egg laid ability was 120.8 ± 13,80 eggs/ female (Sudarmani, 2004). Red
spider mite prefer sunlight, thus tea plants which are cultivated in area without shade will

be damaged more severely than that with shade (Das, 1959b). In southern India, red
spider mite has successive generations and appears on tea plants throughout the year and
the density reaches a peak from March to April. Low temparature, high humidity and
heavy rain has detrimental influence to the development of red spider mite (Sudarmani,
2004).
1.2.2. Actual situation of insecticide utilization to control red spider mite on tea
In Shizuoka (Japan), tea growners spray 16.9-21.6 times per year and 4.1-8.1 times
per year in average to control insect pest and disiease pest, respectively (Takafuji and
Amano, 2001). Recently, there are number of new insecticides such as Propagite,
Fenpyroximate, Hexythiazox, Bifenthrin, Fenazaquin and Spiromesifen has been used to
manage red spider mite (Anomyous, 2012; Babu and Muraleedharan, 2010; …).
1.2.3. Resistance of red spider mite
The repeated use of acaricide leads to the increase in serious damage of red spider
mite to tea production. The decline of susceptibility of red spider mite against insecticide
groups is one of the reasons for increasing number of populations (Sarker and
Mukhopadhyay, 2008; Roy et al., 2008; Shahoo et al., 2003). According to Roy (2009),


3

among chemicals which have been tested on red spider mite populations in Terai and
Dooars - India, LC50 of Ethion and Dicofol were higher than 300ppm. LC50 of Propagite
were 46.246 and 97.110 in average in Terai and Dooars, respectively. That of Fenazaquin
and Fenpropathrin were less than 10ppm. In northern of Bengal, India, the resistance
against 5 chemicals namely Ethion, Dicofol, Propargite, Fenazaquin and Fenpropathrin
of red spider mite have observed and the results showed that Terai popupation had lowest
susceptibility to all of them in comparision with Dooars pupolation. Susceptibility level
corresponds to number of acaricides in 2 regions indicated selective population pressure
caused by acaricide (Roy et al. 2010a). In laboratory, LC50 value of Ethion, Dicofol,
Profenofos, Propargite, Fenpropathrin, Ferazaquin and Abamectin of populations in the

northern of India were 687.18ppm, 534.04ppm, 241.684ppm, 90.256ppm, 12.549ppm,
4.319ppm, 2.405ppm, respectively. Among number of acaricide, Abamectin has highest
toxic and Ethion is opposite. LC50 values went down corresponding to egg-killed
insecticides namely Fenazaquin, Profenofos, Propagite, Fenpropathrin, Ethion, Dicofol
and Abamectin, respectively (Roy et al., 2012). In Terai, India, population in which
Ethion group were used frequently, LC50 value was 79-100 times higher in comparision
with others where acaricide was not used. The result was similar with Fenpropathrin in
which LC50 value was 73-108 times higher than others without using acaricides (Soma et
al., 2017).
1.2.4. Management of the resistance of red spider mite
According to Sudarmani (2004), in north India, the proportion of tea leave which is
infected by red spider mite in tea field without shaded trees was high because of high
temperature and long lighting time on leave. Tea plant with shaded trees develops well
and reduces number of red spider mite. According to Roy et al. (2010a), egg-killed
insecticide utilization is one of the strategic solution for red spider mite management.
Roy et al. (2010b) also said that at egg stage, Fenazaquin had lowest value of LC50,
followed by Profenofos, Propargite, Fenpropathrin, Ethion, Dicofol, Abamectin and
Azadiractin, respectively.
The process of red spider mite management includes: 1) Measures should be taken
(Two rounds of spray at 15 days interval) during December and January in young and
unpruned tea; skiffed tea – February; pruned tea – early March; 2) after severe attack of
mite impose two rounds of applications must be followed at an interval of 7 -10 days
(April – October: 7 days and Nov-March: 10 days); 3) avoiding an application of sulfur
formulation during hot sunshine and dry spell; 4) collecting tea leaves on the surface; 5)
during full cropping seasons spraying should be undertaken as spot treatment only; 6) for
pruned tea monitoring is necessary soon after tipping; 7) avoid spraying at noon in sunny
weather; 8) mixing of acaricides with foliar nutrients, insecticides and others should be
avoided for retaining the toxicity of the acaricides and better control in red spider prone
sections; 9) remove serious infected tea plants; and 10) thorough drenching of top,
middle and bottom hamper of bushes with pray fluid spray fluid is mandatory to kill the

residual population (Das, 1960; Gurusubramanian và Borthakur, 2005).


4

1.3. Studies in Vietnam
1.3.1. Biological, ecological characteristics and development regulation of red spider
mite
Nguyen Van Dinh (1994) reported that there were 3 spider mite spicies on tea:
false spider mite, red spider mite and broad mite. The red spider mite is the most
dangerous one among them.
Adult has 4 pair of legs, segmented leg with a lot of scattered sharp hairs. The
body is separated into 2 parts, the head and chest + abdomen with the size are 0,06 –
0,09mm x 0,05 – 0,07mm, 0,25 – 0,31mm x 0,17 – 0,24mm, respectively. One to two
days after hatching, female starts laying eggs which have flat sphere shape and the size is
around 0,09-0,12mm. There is a curve and small hair in the middle of the egg. New egg
laid has light pink color, then turn to red-brown and getting dark brown before hatching.
New hatching red spider mite has light pink body, the size is 0,13-0,15mm x 0,100,12mm with 3 pair of legs (Nguyen Van Hung and Nguyen Van Tao 2006). In the
laboratory condition with the temperature and relative humidity (RH) are 27,5oC and
81,6%, respectively, lifetimes of red spider mite on Trung Du Xanh and PH1 varieties are
10,70 days and 10,86 days, respectively (Pham Thi Mai, 2010). Depend on
environmental conditions, particularly temperature, red spider mite’s lifespan vary from
11,2 to 12,8 days. Each female is able to lay up to 79 eggs, oviposition rate is highest at
the date of 5th – 10th from the first day of laying egg. Female can lay egg during 20 days.
The most favourite temperature for the development of red spider mite is 30 oC, number
of egg laid increase to 88 eggs/each and lifetime is only 11,2 days compared to 12,8 days
at 25oC (Nguyen Thai Thang, 2000). According to Nguyen Khac Tien (1994), red spider
mite is the most dangerous insect pests on tea. There are two peak of density per year, the
1st is from Ferbruary to May and the 2nd is from September to November.
1.3.2. Actual situation of insecticide utilization to control red spider mite on tea

The number of spraying varied from 9 to 16 times per year in key points of tea
plantation in Ba Vi district, periodic spraying rate is still high, up to 75% and most of
farmers spraied without “4 right regulation” (Nguyen Thi Bich Thuy, 2009). According
to the investigation in Thai Nguyen province from 2005 to 2006, 28.8% to 33.3% of
interviewed farmers admitted that they spraied insecticide less than 16 times per year
while 60.0%-66.7% of interviewers did 16 to 20 times per year (Nguyen Van Toan and
Pham Van Lam, 2014).
1.3.3 Resistance of red spider mite
Although insecticides which have been spraied on tea plant, have broad spectrum
effects, however, do not work well with red spider mite and they even promote the
development of this pest. Otherwise, those chemicals destroy natural enemies, thus red
spider mite is able to develop much more than before spraying (Nguyen Van Hung and
Nguyen Van Tao, 2006).
1.3.4. Management of the resistance of red spider mite
There is not any deeply research on resistance of red spider mite against chemical
in Vietnam. There are some researches on management of red spider mite on tea (Nguyen
Van Dinh, 1994; Luong Thi Huyen, 2017; Nguyen Tran Oanh, 2012; Nguyen Thai
Thang, 2000; Nguyen Thi Thu et al., 2016; Vu Thi Thuong et al., 2015).


5

CHAPTER II
MATERIAL, CONTENTS AND METHODOLOGY
2.1. Location and schedule
The research has been conducted in the laboratory and greenhouse in Plant
Protection Research Institute (PPRI), in the field in Thai Nguyen province and Phu Tho
province from 2014 to 2018.
2.2. Materials and equipments
Pesticies, tea varieties, equipments in lab and on tea fields.

2.3. Contents
- Investigation and evaluation of actual situation of insecticide utilization in
controlling red spider mite in Thai Nguyen province and Phu Tho province.
- Determination of resistance formation of red spider mite against common
acaricides
- Evaluation of resistance development and across-resistance ability of red spider
mite against common acaricides.
- Research on some solutions to manage resistance of red spider mite in IPM
method.
- Building model and propose technical measures to control resistance of red
spider mite in IPM method.
2.4. Methodology
Investigation of pesticide utilization on tea in Thai Nguyen province and Phu Tho
province accroding to general method (Dao Trong Anh, 2002).
Rearing susceptible red spider mite strains which were collected from the field
accoring to the method of Helle and Sabelis (1985). Determine resistance level of red
spider mite according to the method of IRAC (2009) and Sato et al. (2005).
Investigate population dynamic of red spider mite according to QCVN 01-118
issued by MARD (2012), Sudarmani (2004), Nguyen Van Hung and Nguyen Van Tao
(2006).
Investigate natural enemies on tea according to the method of Pham Van Lam
(1997). Evaluatie effectiveness of acaricides according to the method of Kumari et al.
(2012), Knight et al. (1990).
Evaluate the effectiveness of alternative utilization of management resistance of
red spider mite against insecticides according to Le Truong et al. (2005) and Nguyen
Tran Oanh (2012).
Building model and propose technical measures to control resistance of red spider
mite in IPM method based on the research’s results and Intergrated Tea Management
Process (Nguyen Van Hung and Nguyen Van Tao, 2006).
2.5. Analysis

The efficacy of insecticides was canculated by Abbott formula (1925) ; Sarmah
(1999) and Henderson-Tilton (1995). LC50 was calculated by Finney's 1971 Probit
program. Resistance indices (Ri) was determined according to FAO (1980).
Data was processed by IRRISTAT 5.0 program


6

CHAPTER III
RESULTS AND DISCUSSION
3.1. Field investigation of pesticide utiliation’s status in red spider mite management
in Phu Tho province and Thai Nguyen province
3.1.1. Insects and spider mites on tea in Thai Nguyen province and Phu Tho province
3.1.1.1. Insects and spider mites on tea through interview with farmers
In two research area, green hopper and mosquito bug are two major insects on tea.
The ratio of farmers who consider that green hopper is the most popular one in Thai
Nguyen province and Phu Tho province were 99.8% and 97.1%, respectively. In term of
posquito bug, those were 77.1% and 70.9%, respectively. In Thai Nguyen province, the
percentage of farmers who believe that red spider mite is serious threat to tea production
was 81.0% in average meanwhile it was 67.3% in average in Phu Tho province.
3.1.1.2. Insects and spider mites on tea through field investigation
In 2004, we found 13 spieces on tea including insects and spider mite in Thai
Nguyen province and Phu Tho province. The common spicies (with frequency encounter
is over 50%) were green hopper, mosquito bug, and red spider mite in Thai Nguyen
province and mosquito bug and red spider mite in Phu Tho province.
3.1.2. Pesticie utilization status in pest management on tea
3.1.2.1. Number of pesticide application on tea in one year
According to an interview in Hoa Binh commune, La Bang commune, and Phan
Me commune (Thai Nguyen province) in 2014, tea growners spraied 14.4 times/year in
average (vary feom 12.37 to 16.89 times). In Phu Tho province, the interview was

conducted in Phu Ho commune, Tien Phu commune, and Vo Mieu commune, the result
illustrated that tea growners applied pesticides with lower quantity than that in Thai
Nguyen province and the average application was 12.0 times per year (vary from 9.82 to
14.16 times).
3.1.2.2. Concentration and doze
Table 3.4. Concentration of insecticides and acaricides were used in 2014
Increase in comparison with
Percentage of applicant (%)
recommendation (times)
Thai Nguyen1
Phu Tho2
Recommendation
71,27
78,15
> 1 to 2
19,38
15,74
> 2 to 3
8,39
5,68
>3
0,96
0,43
Notice:
1. Investigation sites: Hoa Binh commune (Dong Hy district); La Bang commune (Dai Tu
district); Phan Me commune (Phu Luong district)
2. Investigation sites: Phu Ho commune (Phu Tho district); Tien Phu commune (Phu Ninh
district); Vo Mieu commune (Thanh Son district)

The percentage of tea growners who applied accurate concentratin and doze

according to recommendation of producers were quite high with 71.27% in Thai Nguyen
province and 78.15% in Phu Tho province. In Thai Nguyen province, 8.39% of


7

interviewers said they applied pesticides with 2-3 times in comparision with the
recommendation from producers. In term of Phu Tho province, it was 5.68%. The
number of farmer who increased concentration and doze of pesticide in Thai Nguyen
province was higher than that in Phu Tho province (Table 3.4).
3.1.2.3. Sort of pesticide
The active ingredients namely Abamectin and Emamectin benzoate (Avermectin
group) were used popularly to control insect pests on tea. The percentage of farmer
households who applied abamectin were 31.32% and 26.93% in Thai Nguyen province
and Phu Tho province, respectively. Otherwise, the ratio of farmer households who
spraied Emamectin benzoate were 10.19% and 18.15%, respectively. In term of other
active ingredients, the numbers varied from 0.14% to 6.34% in Thai Nguyen province
and from 0.02% to 5.16% in Phu Tho province. The mixture of pesticides applying to
control insect pests on tea was a combination between abamectin and emamectin
benzoate (3.67% farmer households used/ highest) and mixture of Fenitrothinon and
Trichlorfon (5.16% farmer households used/ highest) in Thai Nguyen province and Phu
Tho province, respectively.
Table 3.7. Single active ingredients were used to manage red spider mite
in 2014
Proportion of households
Toxic
using (%)
Groups
Active ingredients
group*

Thai Nguyen1
Phu Tho2
Abamectin
II
19.16
26.37
Avermectin
Emamectin benzoate
II
8.45
15.02
Điều hòa sinh
Hexythiazox
III
3.67
2.78
trưởng
Este sulfite
Propargite
III
10.18
8.67
Focmamidin
Diafenthiuron
III
4.49
Lân hữu cơ
Dimethoate
II
4.24

Pyrazol
Fenpyroximate
II
6.30
9.47
Pyrethroid
Acrinathrin
III
1.16
5.54
Pyridazinon
Pyridaben
III
5.41
3.28
Azadirachtin
IV
3.51
7.27
Botanical
insecticide
Matrine
III
3.39
4.41
B. thuringiensis var.
III
0.13
kurstaki
Biopesticide

B. thuringiensis
III
0.25
var. T36
Triazapentadiene
Amitraz
III
2.78
Notice: Toxic group *: according to WHO -: Do not use
1. Investigation sites: Hoa Binh commune (Dong Hy district); La Bang commune (Dai Tu
district); Phan Me commune (Phu Luong district)
2. Investigation sites: Phu Ho commune (Phu Tho district); Tien Phu commune (Phu Ninh
district); Vo Mieu commune (Thanh Son district)


8

Table 3.8. Mixtural pesticides used for management of red spider mite on tea in
2014
Toxic
Proportion of
*
group
households using (%)
Groups
Ingredients
Thai Nguyen1
Phu
Tho2
Avermectin,

Abamectin + Chlorfluazuron
II+II
0,35
Benzoylurea
Avermectin,
Abamectin +
II+III
0,37
Diamide
Chlorantraniliprole
Avermectin,
Abamectin + Acetamiprid
II+II
3,78
2,36
Neonicotinoid
Abamectin + Imidacloprid
II+III
2,39
Avermectin, Dầu
khoáng
Avermectin,
Phenylpyrazole
Avermectin,
Pyrethroid

Avermectin,
Botanical
insecticide
Avermectin,

microbial
insecticide
Botanica
insecticide

Abamectin + Petroleum oil
Emamectin benzoate +
Petroleum oil

II+III

1,07

4,07

II+III

0,42

-

Abamectin + Fipronil

II+II

0,96

2,43

4,85

1,48

2,91

-

2,46

3,58

0,27

-

0,88

-

3,54

3,27

Abamectin + AlphaII+II
cypermethrin
Abamectin +
LambdaII+II
cyhalothrin
Abamectin + Matrine
II+III

Abamectin+ Azadirachtin+
II+IV+I
Emamectin benzoate
I
Emamectin benzoate +
II+IV
Azadirachtin
Emamectin benzoate + Matrine II+III
Abamectin + Bacillus
thuringiensis var. kurstaki

II+III

1,29

-

Azadirachtin + Matrine

IV+III

1,34

-

Noitice: *: Toxic group: according to WHO , - :do not use
1. Investigation sites: Hoa Binh commune (Dong Hy); La bang commune (Dai Tu); Phan Me
commune (Phu Luong)
2. Investigation sites: Phu Ho commune (Phu Tho); Tien Phu commune (Phu Ninh); Vo Mieu
commune (Thanh Son).

Abamectin was the most popular active ingredient which applied to control re
spider mite on tea. Proportion of households used above chemical were 19.16% and
26.37% in Thai Nguyen province and Phu Tho province, respectively. Follow by
Abamectin, Propargite was the 2nd popular active ingredient which was chosen by


9

farmers in Thai Nguyen province meanwhile Emamectin benzoate was chosen in Phu
Tho province with 10.18% and 15.02%, respectively. Other ingredients had low
proportion, varied from 0.13% to 8.45% and 2.78% to 9.47%, respectively (table 3.7).
In investigation sites in Thai Nguyen province, Abamectin + Alpha cypermethrin was the
most popular mixtural pesticides to manage red spider mite with the proportion of
households using reached 4.85%; follow by other combination of Abamectin +
Acetamiprid (3.78%) and Emamectin benzoate + Matrine (3.45%). There were 0.27% of
interviewed household mixed 3 active ingredients. In Phu Tho province, two mixtural
ingredients of Abamectin + Petroleum oil got highest percentage; follow by the
combination of Abamectin + Matrine and combination of Emamectin benzoate + Matrine
with the proportion of 3.58% and 3.27%, respectively (table 3.8).
3.1.2.4. Arcaricide utilization’s situation in some local areas
There were 14 active ingredients (10 groups) which have been applied to control
red spider mite in La Bang commune (Thai Nguyen province). Abamectin had highest
percentage using of households with 28.31%. In term of Emamectine, it was 16.39% and
that of others varied from 0.64% to 12.37%. In Phu Ho commune (Phu Tho province),
tea growners have applied 10 active ingredients (9 groups) to manage red spider mite.
With 43.1% of households using, Abamectine was the first choice of farmers, follow by
Emamectin benzoate, Fenpyroximate, Propargite with proportion of 14.57%; 15.44%;
and 12.76%, respectively. Utilization ratio of other active ingredient in Phu Ho commune
was from 0.14% to 4.73%.

3.2. Resistance level of red spider mite against some common acaricides using in tea
production
3.2.1. Resistance level of red spider mite against some chemicals
3.2.1.1. Thai Nguyen population
Thai Nguyen population had highest Ri with Dimethoate among all experimental active
ingredients and it was 14.3. In term of other active ingredients including Fenpropathrin,
Propargite, Abamectin, and Emamectin benzoate, Ri were 11.6; 11.3; 11.3; and 11.2,
respectively. Otherwise, Ri of Thai Nguyen population was 10.3 with Fenpyroximate
and Pyridaben. They were 3.2; 5.3; 3.; and 4.6 with Azadirachtin, Matrine, Rotenone,
and Hexythiazox (table 3.11)


10

Table 3.11. Resistance level of red spider mite against some common chemicals in
Dai Tu commune (Thai Nguyen) (PPRI, 2014)
Active
ingredients
Dimethoate
Fenpropathrin
Fenpyroximate
Hexythiazox
Propargite
Pyridaben
Abamectin
Azadirachtin
Emamectin
benzoate
Matrine
Rotenone

Commercial
name
Bini-58
40EC
Danitol
10EC
Ortus
5SC
Nissorun
5EC
Comite
73EC
Alfamite
15EC
Catex 1.8EC
Trutat
0.32EC
Tasieu 1.9EC
Sokupi
0.36SL
Trusach
2.5EC

LC50 (ppm) and limited value of 95%
Populations collected in
Thai Nguyen
1228,8634
(1041,4096-1437,7701)
159,0812

(137,6135-183,7388)
42,134
(38,6907-45,8841)
14,0742
(12,7715-15,4957)
181,1582
(158,7714-206,7015)
29,9091
(26,7726-33,0650)
0,7865
(0,7098-0,8714)
2,3642
(2,1745-2,5538)
0,8538
(0,7706-0,9460)
3,5187
(2,9870-4,1415)
2,8251
(2,6360-3,0143)

Susceptible
population
85,9345
(74,0815-99,6840)
13,7139
(11,8838-15,8258)
4,0907
(3,7598-4,4507)
3,0596
(2,7815-3,3656)

16,0317
(14,0629-18,2761)
2,9038
(2,5766-3,2726)
0,0696
(0,06287-0,0770)
0,7388
(0,6937-0,7839)
0,07623
(0,0688-0,0845)
0,6639
(0,5645-0,7807)
0,7636
(0,7436-0,7835)

Ri

14,3
11,6
10,3
4,6
11,3
10,3
11,3
3,2
11,2
5,3
3,7

Notice: Target was adult re spider mite

Collected in Oct. and Nov. 2014

3.2.1.2. Phu Tho population
Resistance index of Phu Tho population was not high with Propargite, Abamectin,
Fenpyroximate and they were 11.5; 11.3; and 10.2, respectively. In term of Matrine and
Azadirachtin, Ri were 4.8 and 4.6 (Table 3.12).
Consequently, Phu Tho population has just shown resistance against Propargite
and Abamectin; it has not clearly displayed resistance against Fenpyroximate and has not
resisted against Azadirachtin, Matrine.


11

Table 3.12. Resistance level of red spider mite against some common chemicals in
investigation site (PPRI, 2014)
Ingredient name

Commercial
name

Fenpyroximate

Ortus 5SC

Propargite

Comite 73EC

Abamectin

Catex 1.8EC

Azadirachtin
Matrine

Trutat
0.32EC
Sokupi
0.36SL

LC50 (ppm) and limit value of 95%
Populations collected in
Phu Ho-Phu Tho
39,5301
(35,1267 - 44,6843)
183,8344
(160,2341 -203,8748)
0,7084
(0,6538-0,8861)
3,3562
(2,8794-3,7653)
3,4262
(2,6583-4,0285)

Susceptible
population
3,8755
(3,2794 - 4,4561)
15,9856
(13,3480 -17,3285)

0,06269
(0,0579-0,07156)
0,7296
(0,6128-0,8463)
0,7138
(0,5166-0,8041)

Ri

10,2
11,5
11,3
4,6
4,8

Notice: Target was adult re spider mite
Collected in Oct. and Nov. 2014

3.3. Resistance development speed and across-resistance ability of red spider mite
3.3.1. The increase of resistance speed of red spider mite
After 12 generations continuously exposed to an active ingredient, LC50 of
experimental active ingredients increased remarkably. LC50 of Abamectin against red
spider mite went up to 15.4 times. In term of Hexythiazox, LC50 increased only 4.6 times.
Otherwise, Pyridaben, Propargite and Fenpyroximate had an increase in LC50 7.0; 7.3;
and 11.5, respectively (table 3.13)
Table 3.13. LC50 of some active ingredients against red spider mite after 12 generation
exposed (PPRI, 2014 - 2016)
LC50 (ppm)
Active
Increase of

Commercial names
Before
ingredients
After treatment LC50 (times)
treatment
0,0696
1,0712
15,4
Abamectin
Catex 1.8EC
Fenpyroximate
Ortus 5SC
4,0907
46,8385
11,5
3,0596
14,0742
4,6
Hexythiazox
Nissorun 5EC
16,0317
117,0314
7,3
Propargite
Comite 73EC
2,9038
20,3266
7,0
Pyridaben
Alfamite 15EC

3.3.2. Reduction of resistance without chemical exposure
After 5 generations without exposition to chemical, LC50 of Abamectin was
reduced the most by 9.3 times. Meanwhile, LC50 of Pyridaben, Fenpyroximate,
Hexythiazox decreased 6.7; 5.7; 5.3 times, respectively. In contrast, LC50 of Propargite
reduced at least, only 4.6 times (table 3.14). That means the resistance of red spider mite
against Propargite was more stable than others.


12

Bảng 3.14. LC50 of some active ingredients after 5 generations without exposure to
chemical (PPRI, 2015 - 2016)
Active ingredients
LC50 (ppm)
Commercial
Reduction of
Before
After
names
LC50 (times)
treatment
treatment
Abamectin
Catex 1.8EC
0,7865
0,0845
9,3
Fenpyroximate
Ortus 5SC
42,1342

7,3920
5,7
Hexythiazox
Nissorun 5EC
14,0742
2,6555
5,3
Propargite
Comite 73EC
181,1582
39,3822
4,6
Pyridaben
Alfamite 15EC
30,1995
4,5074
6,7
3.3.3. Development of across-resistance of red spider mite against some active
ingredients
3.3.3.1. Across - resistance ability of population has been resistant against Abamectin
Red spider mite population (after 12 generation of exposure to Abamectin) resisted
this active ingredient with quite high Ri (24.4%) and it was 16.4% with Emamectin
benzoate (same group of Avermectin). This population did not show across-resistance
phenomenon against active ingredients belong to different groups Azadirachtin, Matrine,
Rotenone, Hexythiazox, Fenpyroximate, Propargite, Pyridaben, Fenpropthrin, and
Dimethoate. Ri value of red spider mite to other groups was low and varied from 0.9 to
2.9 (Table 3.15)
Table 3.15. Across-resistance ability of populations at 12th generation who has been
resistant Abamectin against some other acaricides (PPRI, 2016)
LC50 (ppm)

Commercial
Population has
Active ingredients
Ri
Susceptible
names
been resistant
population
Abamectin
Abamectin
Catex 1.8EC
1,6300
0,0668
24,4
Azadirachtin
Trutat 0,32EC
0,7782
0,7705
1,0
Dimethoate
Bini-58 40EC
238,4909
82,5228
2,9
Emamectin benzoate
Tasieu 1.9EC
1,2890
0,0786
16,4
Fenpropthrin

Danitol 10EC
35,6579
13,3052
2,7
Fenpyroximate
Ortus 5SC
5,9532
3,9688
1,5
Hexythiazox
Nissorun 5EC
3,3246
2,9684
1,1
Matrine
Sokupi 0,36SL
0,7599
0,6440
1,2
Propargite
Comite 73EC
20,2202
15,5540
1,3
Pyridaben
Alfamite 15EC
8,2544
2,8172
2,9
Rotenone

Trusach 2,5EC
0,5767
0,6785
0,9
Population (after 18 generations of exposure to Abamectin) which has been
resistant against this active ingredient, has been evaluated across-resistance against other
active ingredients which have been applied to control red spider mite. The result
illustrated that population which has been sresistant Abamectin, also showed high


13

resistant against this active ingredient itself and others in the same group. Ri of above
population to Abamectin was highest and it was 31.4. To Emamectin benzoate (same
group of Avermectin), it was 24.4. In term of active ingredients belong to other groups
(Pyridaben, Fenpyroximate, Propargite), Ri of this population were low and varied from
1.3 to 2.9 (table 3.16).
Table 3.16. Across-resistance ability of 18th generation of red spider mite who has
been resistant Abamectin against some other acaricides (PPRI, 2016)
LC50 (ppm)
Commercial
Active ingredients
Ri
Resistance against
Susceptible
names
Abamectin
population
Abamectin
Catex 1.8EC

2,1352
0,0680
31,4
Emamectin benzoate
Tasieu 1.9EC
1,66408
0,0682
24,4
Fenpyroximate

Ortus 5SC

6,0861

4,0574

1,5

Propargite
Comite 73EC
20,67156
15,9012
1,3
Pyridaben
Dandy 15EC
8,456859
2,8863
2,9
Consequently, population which has been resistant Abamectin did not show
across-resistance against other active ingredients belong to different groups Pyridaben,

Fenpyroximate, and Propargite. Its shown that population which has been resistant
abamectin from 12th to 18th generation (after 6 generations of exposure to Abamectin), Ri
has increased significantly from 24.4 to 31.4. In term of Emamectin benzoate, it went up
from 16.4 to 24.4 (Table 3.15 and table 3.16).
3.3.3.2. Across-resistance ability of population which has been resistant against
Propargite
Table 3.17. Across-resistance ability of 23th generation of red spider mite which has
been resistant Propargite against some other acaricides (PPRI, 2016)
LC50 (ppm)
Commercial
Active ingredients
Ri
Resistance against
names
Susceptible
Abamectin
Abamectin
Catex 1.8EC
0,0922
0,0668
1,4
Azadirachtin
Trutat 0,32EC
0,7089
0,7705
0,9
Dimethoate
Bini- 58 40EC
208,7827
82,5228

2,5
Emamectin benzoate
Tasieu 1.9EC
0,0967
0,0786
1,2
Fenpropathrin
Danitol 10EC
0,0967
0,0786
1,2
Fenpyroximate
Ortus 5SC
5,3579
3,9688
1,4
Hexythiazox
Nissorun 5EC
3,3246
2,9684
1,1
Matrine
Sokupi 0.36SA
0,5732
0,6440
0,9
Propargite
Comite 73EC
205,0017
15,5540

13,2
Pyridaben
Alfamite 15EC
0,0922
0,0668
1,4
Rotenone
Trusach 2.5EC
0,4546
0,6785
0,7


14

Population (after 23 generations of exposure to Propargite) which has been
resistant Propargite, showed high resistance against Propargite itself. Ri of this population
reached a peak at 13.2. There was not any report of the resistance of this population
against other active ingresients belong to different groups. Ri of above population to
other active ingredients varied from 0.7 to 2.5. They have not shown across - resistance
phenomenon against Dimethoate, Ri was 2.5 only (table 3.17).
3.4. Solutions in management of resistance of red spider mite in IPM method.
3.4.1. Variety
Red spider mite usually arises and reaches a peak of density twice per year in May
and October. Trung Du variety has highest density of 6.43 individuals/ leave at the peak
in the end of May. At the same time, the density of red spider mite on other varieties
LDP1, TRI 777, PH8 was lower than that of Trung Du variety and they were 6.29; 5.61;
and 5.02 individuals/ leave, respectively. In term of Kim Tuyen, Phuc Van Tien variety,
red spider mite’s density were significant lower at 4.37 and 4.06 individuals/ leave,
respectively. Farmer should choose tea varieties which are less infected by red spider

mite when they cultivate new plants.
3.4.2. Cultivation measures
3.4.2.1. Cultivation shaded tree
The density of red spider mite on tea field with shaded tree is always higher than
that without shaded tree. At the peak of density, there were 6.15 and 9.29
individuals/leave in plantation area with and without shaded tree, respectively.
Consequently, planting shaded tree leads to the reduction in using acaricide.

Fifure 3.2. The effectiveness of shaded tree on density of red spider mite on Trung
Du variety (La Bang, Dai Tu, Thai Nguyen, 2015)
Notice: Treatment 1: Density of red spider mite on tea field with sahded tree
Treatment 2: Density of red spider mite on tea field without sahded tree

3.4.2.2.The effect of branch cutting method
The density of red spider mite reached a peak at the end of May 2015 in Treatment
1 and it was 5.14 individuals/leave, meanwhile it was 8.07 head/leave in term of
Treatment 2. In conclusion, the density in former was significant lower than that of the
latter. It was extremely consistent with previous researches conducted by Das (1960) and
Nguyen Van Dinh (1994). In addition, application of the former method helps to reduce
pressure of using acaricide.


15

Figure 3.3. The impact of branch cutting method on red spider mite on Trung Du
variety (La Bang, Dai Tu, Thai Nguyen, 2015)
Notice: Treatment 1: Pruning (40cm from the ground)
Treatment 2: Pruning (60cm from the ground)
3.4.2.3. Fertilizer application on tea
Density of red spider mite on tea in different treatments of using fertilizer were all

over prevention threshold (6 individuals/leave). In the tea field where was applied
inorganic fertilizers (treatment no.1) density reached a peak at 9.2 – 11.2
individuals/leave in May. On the contrary, in the tea field where organic fertilizer “Song
Gianh” and inorganic fertilizers were applied (treatment no.2 and treatment no.3), density
was lower than in the treatment where only inorganic fertilizers were applied (density
reached a peak at 7.3-9.1 individuals/leave in May). In treatment no.2 and treatment no.3,
the utilization of organic fertilizer helps tea plant develops well leads to the reduction of
red spider mite’s density. Density of red spider mite, however, was not significant
different among treatments.
3.4.3. Natural enemies’ protection
3.4.3.1. Component of spider mite’s natural enemies
Table 3.18. Component of spider mite’s natural enemies on tea
(La Bang, Dai Tu, Thai Nguyen, 2015)
Frequency of
Scientific names
Family
Class
encounter
Oligota sp.
Staphylinidae
Coleoptera
+
Stethorus sp.
Chrysopa sp.
Scolothrips sexmacultus Pergrande
Amblyseius sp.

Coccinellidae
Chrysopydae
Thripidae

Phytoseiidae

Coleoptera
Neuroptera
Thysanoptera
Acarina

++
+
+
+

Notice: - : very rare, Frequency of encounter <5%; +: rare, Frequency of encounter from 5% to 20%;
++: popular, Frequency of encounter from 20% to 50%; +++: very popular, Frequency of encounter over
50%.


16

In Thai Nguyen province, 5 species were reported as natural enemies of red spider
mite. Stethorus sp. was the spicies with highest frequency of encounter among them.
Others were Amblyseius sp., Chrysopa sp., Oligota sp. and Scolothrips sexmacultus.
3.4.3.2. The effectiveness of acaricide on narutal enemies of red spider mite
The arangement of experimental active ingredients which affect to predator species
of red spider mite from high to low were Pyridaben, Fenpyroximate, Propagite and
Hexythiazox. The protection of natual enemies helps to decrease the pressure of using
acaricide.
Table 3.19. The effectiveness of acaricide on narutal enemies of red spider mite (La
Bang, Dai Tu, Thai Nguyen, 2015)
Total density of predator (individual/tray)

Investigatio
Comite 73EC
Dandy 15EC Nissorun5EC Ortus 5SC (1,0
Control
n time
(1,0 L/ha)
(1,5 L/ha)
(0,6 L/ha)
L/ha)
(water)
TPL1
0,19
0,20
0,18
0,16
0,17
7 NSPL1
0,01
0
0,05
0
0,19
14 NSPL1
0,03
0
0,09
0
0,28
21 NSPL1
0,06

0
0,12
0
0,27
TPL2
0,13
0,04
0,22
0,03
0,33
7 NSPL2
0,01
0
0,09
0
0,29
14 NSPL2
0,02
0
0,18
0
0,34
21 NSPL2
0,05
0
0,22
0
0,32
TPL3
0,06

0
0,28
0
0,28
7 NSPL3
0
0
0,08
0
0,23
14 NSPL3
0
0
0,17
0
0,30
21 NSPL3
0
0
0,21
0
0,29
Notice:

TPL1: Before treatment no.1
NSPL1: DAT no.1
TPL2: Before treatment no.2

NSPL2: DAT no.2
TPL3: Before treatment no.3

NSPL3: DAT no.3

3.4.4. Pesticide application
3.4.4.1. Determination of pesticide
To evaluate effect of chemmicals ((Catex 1.8EC, Tasieu 1.9EC, Sokupi 0.36SL,
Trutat 0.32EC, Comite 73EC, Dandy 15EC, Nissorun 5EC, Ortus 5SC) which used to
control red spider mite, we conducted experiments in laboraroty, greenhouse and in the
field. The result showed that the effectiveness of Catex 1.8EC, Tasieu 1.9EC, Sokupi
0.36SL, Trutat 0.32EC were not high and it varied from 68.26% to 79.98% at 5DAT.
Otherwise, Comite 73EC, Dandy 15EC, Ortus 5SC had higher effectiveness than the
formers. Particularly, the effectiveness of Dandy 15EC, Ortus 5SC reached a peak of
81.07% – 83.82% at 3DAT before reducing and it was 65.77%-68.05% at 14DAT. On
the contrary, that of Comite 73EC, Nissorun 5EC had increased over time (the


17

effectiveness of Comite 73E reached a peak of 82.86% at 14DAT and it was 78.54% at
21DAT in term of Nissorun 5EC).
3.4.4.2. Measures to improve the effectiveness of pesticide use
a. Determine the location of red spider mite on tea
Red spider mite prefer to contribute on the upper of leave surface. There was 62%
- 69.4% of red spider mite appear on the upper surface of tea leave. The red spider mite
mainly concentrates in the lower canopy layer and the middle canopy layer, while the
upper canopy layer has the lowest number of individuals. At the peak of the density, the
proportion of red spider mite concentrates in the middle and lower layers of tea canopy
was 79.2% - 79.8%. This result indicated that when spraying, it is necessary to carefully
spray both sides of tea leaves and all layers.

Figure 3.5. Population dynamic on tea surface of Trung Du variety

(La Bang, Dai Tu, Thai nguyen, 2015)

Figure 3.6. Population dynamic on tea layers of Trung Du variety
(La Bang, Dai Tu, Thai nguyen, 2015)
b. Use spraying tools to improve efficiency of arcacide utilization
The efficiency of all three kinds of knapsack was highest at 14DAT spraying
Comite 73EC (71.91% - 87.73%). High pressure knapsack and motoring knapsack hot
higher effectiveness than handle one.


18

Table 3.26. The efficiency of spraying tools using Comite 73EC to control red spider
mite (La bang, Dai Tu, Thai Nguyen, April 2015)
Droplet’s Density
Efficiency (%) at different DAT
size (mm) before
Spraying tools
treatment
14
21
3 NSP 5 NSP 7 NSP
(individual/l
NSP
NSP
eave)
Handle knapsack
> 0,3
13,41a
50,20a 63,64a 71,79a 71,91a 59,51a

12 L
Motoring
0,2 - 0,3
12,93a
62,69ab 77,42ab 83,86b 85,14b 68,27a
knapsack 25L
High pressure
< 0,2
12,50a
67,29b 83,87b 85,94b 87,73b 70,16a
knapsack
12,21a
Control
LSD0.05
CV (%)

2,50
10,4

13,35
11,1

17,02
11,5

10,53
6,5

7,81
4,8

14,92
11,3

Notice: DAT: Day after treatment
Mean values followed by the different letters within a column are significant difference at
P<0.05

c. Determine development stage of red spidermite sensitive to pesticides
Comite 73EC, Nissorun 5EC, Dandy 15EC và Ortus 5SC had high effectiveness at
egg stage. Meanwhile Sokupi 0.5SL, Reasgant 1.8EC, Dandy 15EC higgly affected at
stages from 1st instar to adult. In term of Comite 73EC và Ortus 5SC, the efficiency was
high when red spider mite was 1st and 2nd instar.
d. Alternative utilization of pesticides to manage resistance
Table 3.32. The efficiency of alternation in resistance management of red spider
mite (La Bang, Dai Tu, Thai Nguyen 2015)
LC50 (ppm)
Dynamic of
LC50
Treatment
Alternation
Before
3 times after
(times)
spraying
spraying
Matrine (Sokupi 0.36SL) 1
Azadirachtin (Trutat 0.32EC) 29,9091
26,6191
- 0,89

Matrine (Sokupi 0.36SL)
Abamectin (Catex 1.8EC) 2
Propargite (Comite 73EC) 29,9091
55,3318
+ 1,85
Pyridaben (Alfamite 15EC)
Pyridaben (Alfamite 15EC) 3
Pyridaben (Alfamite 15EC) 29,9091
71,7818
+ 2,40
Pyridaben (Alfamite 15EC)
Notice: Determine LC50 of Pyridaben (Alfamite 15EC);
“-“ decrease, “+” increase


19

Matrine was used for 1st and 3rd spraying while the 2nd was Azadirachtin. The
alteration led to the reduction in LC50 of Pyridaben one year later (0.89 times). The 1st
application was Abamectine, the 2nd and the 3rd were Propargite and Pyridaben. This
alternation caused the increase in LC 50 of Pyridaben after one year. Without
alternation (applied Pyridaben for all 3 times of spraying), one year later, LC 50 went
up 2.4 times (table 3.32).
3.5. Building model and propose solution to manage resistance of red spider mite in
IPM method
3.5.1. Efficiency of the model
3.5.1.1. Reduction in number of pesticide application
In 2015 and 2016, number of pesticide application reduced 6 times and 5 times in
experimental fields in comparision with out of model fields, respectively. Number of
acaricide application in the model was 2 times less than that out of model.

Table 3.33. Number of pesticide application on tea field in and out of the model (La
Bang, Dai Tu, Thai Nguyen, 2015-2016)
Index
Unit
2015
2016
MH
NMH
MH
NMH
Fungicide
Times
3
4
3
3
acaricide
Times
3
5
3
5
Insecticides
Times
3
4
3
4
Combination of insecticide and
Times

0
2
0
2
fungicide
Total number of application
Times
9
15
9
14
Comparision
%
72,22
100
72,73
100
Notice: MH: In the model; NMH: Out of the model

3.5.1.2. Slow down the development of red spider mite population

Figure 3.7. Population dynamic of red spider mite on Trung Du variety in and out
of the model (La Bang, Dai Tu, Thai Nguyen)
In the model, there was only 3 times of acaricide application with the alternation
among different mechanisim acaricides, however, density was significant lower than that
the density on tea field out of model. The peak in April 2016 was 4.46 – 4.59


20

individuals/leave and in October 2016 was 4.91 individuals/ leave. Although spraying 5 –
6 times, however, the density of red spider mite in the tea field out of model was quite
high and over prevention threshold and it was always higher than density of spider mite
in the model. At the peak in April and October 2016, the density were 18.2 and 9.3
individuals/ leave, respectively (figure 3.7).
3.5.1.3. Slow down resistance of red spider mite against acaricides
In the model, acaricides were applied alternatively. Consiquently, Ri had been
reduction remarkably. Ri with Catex 1.8EC went down from 11.3 (end of 2014) to 8.3
(end of 2016). In term of Alfamite 15EC and Ortus 5SC, Ri decreased from 10.3 (end of
2014) to 8.6 (end of 2016) and from 10.3 (end of 2014) to 7.6 (end of 2016), respectively
(table 3.34).
Table 3.34. Resistance level against chemicals within 2 years applying model (La
Bang, Dai Tu, Thai Nguyen, 2014 – 2016)
Ri
Active
Commercial
Before applying
After applying the model
ingredients
names
the model
MH (2016)
NMH (2016)
(2014)
Abamectin
Catex 1.8EC
11,3
8,3
12,3
Azadirachtin

Trutat 0.32EC
3,2
3,1
3,1
Dimethoate
Bini-58 40EC
14,3
10,3
15,3
Emamectin
Tasieu 1.9EC
11,2
8,7
10,7
benzoate
Fenpropathrin
Danitol 10EC
11,6
8,6
13,3
Fenpyroximate
Ortus 5SC
10,3
7,6
10,5
Hexythiazox
Nissorun 5EC
4,6
4,7
4,5

Matrine
Sokupi 0.36SL
5,3
5,4
5,9
Propargite
Comite 73EC
11,3
10,1
12,8
Pyridaben
Alfamite 15EC
10,3
8,6
12,3
Rotenone
Trusach 2.5EC
3,7
3,6
3,6
Notice: MH: In the model; NMH: Out of the model

Ri of red spider mite had increased with most of experimental chemicals on tea
plant out of the model. Ri went up clearly with Alfamite 15EC (from 10.3 up to 12.3). In
term of Comite 73EC and Catex 1.8EC, Ri rose from 11.3 to 12.8 and from 11.3 to 12.3,
respectively. In case of Ortus 5SC and Sokupi 0.36SL, Ri increased less than the formers.
On the contrary, Ri decreased from 11.2 (end of 2014) to 10.7 (end of 2016) and from 3.2
to 3.1 with Tasieu 1.9EC and Trutat 0.32EC, respectively (table 3.34).
Before building the model (2014), red spider mite population in reseach site has
been resistant againts Catex 1.8EC, Comite 73EC, Alfamite 15EC, Ortus 5SC, Tasieu

1.9EC, Bini-58 40EC, Danitol 10EC. During experimental time, tea growners who
cultivated tea out of the model had used above chemicals. Consequently, after complete
the model (2016), Ri of red spider mite on tea out of the model has been increasing.


21

3.5.1.4. Enhancing effectiveness of pesticide
After 2 years continously using pesticide reasonably in the model, the resistance’s
increase has been restricted. That means the effectiveness of chemical has been
significantly risen. At 5DAT, The effectiveness of Tasieu 1.9EC and Trutat 0.32EC went
up from 68.26%; 76.72% (end of 2014) to 83.36%; 82.28% (end of 2016), respectively.
At 7DAT, the efficiency of experimental chemicals has increased significantly. The
efficiency of Trutat 0.32EC and Tasieu 1.9EC rose from 69.3% and 65.03% (end of
2014) to 81.9% and 83.87% (end of 2016), so on.
Table 3.35. The efficiency of some acaricide in 2014 and 2016 in La Bang (Thai
nguyen)
Evaluation
Efficiency (%) at DAT
Experimental
time
chemicals
3 DAT
5 DAT
7 DAT
14 DAT 21 DAT
10/2014
76,76
78,20
73,43

68,09
60,04
Catex 1.8EC
(0,6 l/ha)
10/2016
72,93
85,93
78,23
74,31
65,41
10/2014
68,67
76,72
69,30
64,73
59,07
Trutat 0.32EC
(0,4 l/ha)
10/2016
79,85
82,28
81,90
77,78
73,44
10/2014
46,08
68,26
65,03
61,61
51,88

Tasieu 1.9EC
(0,3 l/ha)
10/2016
80,19
83,36
83,87
71,53
63,46
10/2014
70,44
79,98
75,80
70,86
63,40
Sokupi 0.36SL
(0,35 l/ha)
10/2016
73,20
80,74
78,59
74,47
66,80
10/2014
68,98
75,65
79,97
82,86
80,34
Comite 73EC
(1,0 l/ha)

10/2016
77,39
82,36
86,59
91,14
83,70
10/2014
83,82
79,75
75,88
68,05
60,25
Dandy 15EC (1,5
l/ha)
10/2016
87,16
88,78
85,73
81,42
70,31
10/2014
29,85
35,43
45,58
75,64
78,54
Nissorun 5EC
(0,6 l/ha)
10/2016
36,39

42,22
51,85
80,75
85,77
3.5.2. The economical effectiveness of the model
Table 3.36. The economical effectiveness of the model
(La Bang, Dai Tu, Thai Nguyen, 2016)
Evaluation index (1ha/year)
In the model
Out of the model
1. Fertilizer (1.000đ)
47.200
42.495
2. Pesticide’ expenditure(1.000đ)
10.680
15.980
3. Others (1.000đ)
85.500
60.900
4. Total (1.000đ, 1+ 2+ 3)
143.400
119.375
5. Average yield (kg):
13.300
12.100
6. Total revenue(1.000đ)
332.500
278.300
7. Benefit (1.000đ)
189.100

158.925
The increase (compare to out of the model) (%)
Notice: price: In the model: 24.000 đ/kg, Out of the model: 22.000 đ/kg

19,0%


22

The model in La Bang (Thai Nguyen) caused the reduction in pesticide‘s
expenditure and it was 5.3m/ha less than that out of the model. On the contrary, tea yield
in the model increased 1.2 times in comparision with that out of the model. Furthermore,
fresh tip’s quality was highly evaluated by consumers. Additionally, the price of tea
production was also higher contributing to the increase profit in the model by 19% higher
than out of the model.
3.5.3. Propose solutions to manage resistance of red spider mite in IPM method in
Thai Nguyen province and Phu Tho province
Based on the result of the research combine to previous reseach’s results which has
been published to propose the solutions manage the resistance of red spider mite by
reasonable use pesticides and application of IPM on tea, the particular solutions were:
* Variety: When farmers cultivate new tea plant, they should choose varieties which are
less infected by red spider mite such as Kim Tuyen variety, Phuc Van Tien variety,...
* Cultivation methods:
- Fertilization: Organic fertilizer; phan huu co vi sinh and inorganic fertilizers are needed
to supply balance and enough
- watering: During dry season, watering 7-10 times/day to ensure that tea plant has
enough water. Apply high pressure watering on both sides of tea leave to remove red
spider mite partly.
- Planting shaded trees is needed when cultivate new tea field.
* Biological method:

- Protection of natural enemies: Do not use chemical consiquently to protect natural
enemies such as Stethorus sp., Oligota sp., Chrysopa sp., Scolothrips sexmacultus,
Amblyseius sp.,…
- If chemical is needed to apply, give a priority for active ingredients which have high
effectiveness to insect pests but less toxic to natural enemies of red spider mite (Nissorun
5EC, Comite 73EC).
* Chemical application:
- Conduct weekly investigation to determine suitable time. Monitoring the appearance of
and damage caused by red spider mite especially in March, April, May, September,
October.
- The utilization of chemical is the last measure when others did not work well. Pesticide
application is used only when density is from 4 to 6 individuals/leave or 20% of old leave
is damaged. Tea field should be investigated often to early find the appearance of red
spider mite and apply prevention spraying to avoid spreading in a large scale.
- Use only chemicals in the list of approved pesticides on tea such as Hexythiazox
(Nissorun 5EC,...) Pyridaben (Alfamite 15EC, Dandy 15EC ...), Propargite (Comite
73EC, Daisy 57EC, ...).
- Priority to alternately use chemicals of groups Matrine (Sokupi 0.36SL,...),
Azadirachtin (Trutat 0.32EC,...), Rotenone (Trusach 2.5EC,...), Abamectin (Catex 1.8EC
,...) and Petroleum spray oil (SK Enspray 99EC,...),…
- Use only once a year with chemical containing active ingredients that red-brown spider


23

has not shown resistance (Ri <10). The chemicals which have been shown resistance by
red spider mite (Ri >10), are restrictive and those chemical should be used only once or
twice per year. Alternative application of chemicals belong to different groups.
- Choose highly effective chemicals which is suitable with development stage of red
spider mite at spraying time. For example, Comite 73EC, Nissorun 5EC và Dandy 15EC

are highly effective to egg stage thus they should be applied when eggs are major on tea
plant. In contrast, Comite 73EC highly affacts to 1st instar and 2nd instar of red spider
mite, it should be selected to control those stages of red spider mite.
- To get high effectiveness in controlling red spider mite, it is needed to carefully spray
both sides of tea leave and all layers.
- Use pesticides according to “4 right principles“ (right time, right chemical, right
concentration and doze and right way) and priority to use high pressure sprayer, carefully
spraying on both sides. The volume of chemical solution is 400-600 l/ha.
CONCLUSIONS AND RECOMMENDATIONS
1. Conclusions
1.1. There are 16 groups with 21 active ingredients (Thai Nguyen province) and 10
groups with 13 active ingredients (Phu Tho province) which have been commonly used
to control red spider mite on tea including Abamectin, Emamectin benzoate, Propargite,
Fenpyroximate, Fenpyroximate and Azadirachtin.
1.2. Red spider mite population in Thai Nguyen province were markedly resistant
against 7 active ingredients namely Dimethoate, Fenpropathrin, Propargite, Abamectin,
Emamectin benzoate, Pyridaben, Fenpyroximate. In term of Phu Tho population, they
have resisted 3 active ingredients namely Abamectin, Propargite and Fenpyroximate.
1.3. Red spider mite, after 12 generations, were exposed to chemical, development
speed of LC50 of Abamectin was 15.4 times, those of Pyridaben, Propargite và
Fenpyroximate were 7.0; 7.3 and 11.5 times, respectively. In term of Hexythiazox,
especially, it was only 4.6 times.
After 5 generations without exposure to chemical, LC50 value of Abamectin had
highest reduction up to 9.3 times. LC50 of Pyridaben and Fenpyroximate decreased by 6.7
times and 5.7 times, respectively. In case of Propargite, LC50 value reduced only 4.6
times.
If red spider mite already resisted against Abamectin, after 12 generations, Ri were
24.4 and 16.4 against Abamectin itself and Emamectin benzoate, respectively. This
population, however, had not across-resistance phenomenon against 8 different active
ingredients with the variation of Ri from 0.9 to 2.9. After 18 generations within exposure

to Abamectin, this population resisted against Abamectin with Ri = 31.4 and Emamectin
benzoate with Ri = 24.4, however, they have not shown resistance ability against other
groups with Ri vary from 1.3 to 2.9.
After 23 generations within exposure to Propargite, the population which resisted this
active ingredient, Ri was 13.2 against Propargite itself and they have not shown up acrossresistance phenomenon against 10 other active ingredients with Ri vary from 0.7 to 2.5.