Post on 26-Apr-2023
Effect of climatic factors, predators and plant
age on the
population dynamics of Empoasca decipiens and
Thrips tabaci on kidney bean plants
M. A. Mohamed, M. H. A. Soliman and H. B. HomamDep. Vegetable Pests, Plant Protection Research
Institute,
Dokki, Giza, 12618 Egypt
ABSTRACT
The present work was carried out to study the
effect of climatic factors (temperature and
relative humidity), associated predators
[Coccinella undecimpunctata L., Scymnus interruptus Coeze,
Chrysoperla carnea (Steph.) and Orius albidipennis
(Reut.)] and plant age on the population density
of Empoasca decipiens Paoli and Thrips tabaci Lind.
infesting bean plants during two successive
seasons. Plant age effect was considered as third
degree of polynomial.
The results indicated that, jassids
population were higher than thrips and had one
peak of abundance on May 28th and 27th and thrips
population had one peak of abundance on May 14th
and 20th during 2005 and 2006 seasons,
respectively. Concerning the total predators, two
peaks occurred during May and June in both
seasons.
The population of E. decipiens was affected
insignificantly by climatic factors in the two
seasons. While the predators had significant
positive effect on jassid population during two
seasons. The population of T. tabaci was affected
insignificantly by the climatic factors and
predators in the two seasons except for minimum
temperature which affected it significantly in
the first season. Plant age affected the
population significantly in the first and second
seasons. This mean that, the plant age had more
effect on Jassid and thrips population compared
with the role of climatic factors and predators.
The explained variance due to plant age was
(87.76 and 95.41%) for jassid, (92.08% and
76.94%) for thrips during two seasons. Plant age
is expected to reflect leaves content of
nutritional values according to plant phenology.
INTRODUCTION
2
Bean plant, Phaseolus vulgaris L. is an important
economic leguminous vegetables crops. It is
cultivated in Egypt for local consumption and
exportation. It contains high percentage of
protein, carbohydrates, vitamins and mineral
salts which are essential for human nutrition.
This crop is subject to be infested by many
pests which cause considerable damage in both
quantity and quality of the pods (El-Kifl et al.,
1974, Chang and Chen, 1993). Jassids and thrips
are considered as the main insect pests infecting
bean and cause partial or complete damage to the
infested leaves and also facilitate and encourage
the infestations with several pathogens.
Information about the interactions between
insects and their natural enemies, density may
become an important integrated part of the insect
management system (Kogan and Herzog, 1980 &
Riudavets 1995).
The present study aimed to evaluate the
effect of plant age, climatic factors (i.e.
temperature and relative humidity) and some
associated predators, on population density of E.
decipiens and T. tabaci on kidney bean.
3
MATERIALS AND METHODS
Field experiments were carried out during the
summer plantations (2005 and 2006 seasons) at
Kaha Agricultural Research Station, Qualubia
Governorate during two successive seasons. The
Kidney bean plant, P. vulgaris Fam. Leguminosae
(variety Giza 3) was planted.
The chosen area (4000 m2) was divided to four
equal replicates. Each replicate about 1000 m2
and planting in the last week of March in both
2005 and 2006. Normal agricultural practices were
followed without insecticides treatments.
To assess the population of jassids and
thrips and main associated predators, weekly
samples of 100 leaves were randomly collected
from the three plant levels (i.e. upper, middle
and lower). The collected samples were kept in a
paper bag and transferred to the laboratory for
investigation. The total number of E. decipiens and T.
tabaci (nymphs and adults) and predators were
counted and recorded. The considered predators
were Coccinella undecimpunctata L. (larvae and
adults), Scymnus interruptus Coeze (larvae and
4
adults), Chrysoperla carnea (Steph.) (larvae) and
Orius albidipennis (Reut.) (nymphs and adults).
The maximum and minimum daily temperatures
and relative humidity were recorded during the
period study and weekly numbers of predators in
relation to the age of bean plant were used for
calculating the simple correlation and multiple
regression values according to Fisher (1950).
Plant age was used as a factor affecting
studied pests population dynamics. The effect of
plant age was assumed to be polynomial of the
third degree (i.e. Y= a + b1x + b2X2 + b3X3). This
relation would indicate three stages of effect of
the plant age on pests population dynamics. The
first one would enhance the population, the
second one would reflect on stability and the
third stage would associate with population
decline. This effect can be evaluated using
multiple regression.
RESULTS AND DISCUSSION
5
1. Population density of E. decipiens and T. tabaci and
associated predators:
Data presented in Tables (1 and 2) show the
natural infestation of kidney bean with E. decipiens
and T. tabaci during two successive seasons of 2005
and 2006. The regular weekly inspections of
kidney bean leaves during two plantation seasons
revealed that the occurrence of E. decipiens and T.
tabaci (nymphs and adults) on this plant as
recorded during the whole two growing seasons
2005 and 2006. Monitor started on April, 23rd 2005
and 22nd 2006 by 1.40 and 2.22 jassids/leaf, 0.25
and 0.22 thrips/leaf, respectively.
During the first season, the population
density of E. decipiens increased up to the 28th of
May, as the highest peak of 13.28
individuals/leaf, while the population density of
T. tabaci increased gradually up to the 14th of May,
as the highest peak observed during this season
was 0.46 individuals/leaf and then decreased
gradually until the end of the season, as it
reached to 1.23 jassids/leaf, 0.05 thrips/leaf.
For the subsequent season 2006, the population of
E. decipiens and T. tabaci had the same trend of the
6
first season, where the highest peak observed was
14.55 jassids/leaf on the May 27th, 0.65
thrips/leaf on the May 20th, and then the
population decreased gradually reached 1.70
jassids/leaf, 0.09 thrips/leaf at the end of the
growing season.
Concerning the target (considered) predators,
Tables (1 and 2) show that all predators were
firstly observed in kidney bean nearly at the
same time as the first appearance of jassids and
thrips. It is apparent that Coccinella undecimpunctata
was the most common predator in kidney bean field
followed by Scymnus interruptus and Chrysoperla carnea
(Steph.) while Orius albidipennis came in the fourth
place.
Considering the total predators, two peaks
occurred, the first peak was in May, 14th and 20th
by 0.75 and 0.85 predators/leaf during two
growing seasons 2005 and 2006, respectively. The
second peak was in June, 4th and 3rd with mean of
1.00 and 1.13 predators/leaf, respectively.
It was clear that, the first peak of predators
occurred in association with the maximum
population of thrips during two growing seasons.
7
In general, the population of E. decipiens, T.
tabaci and associated predators were relatively
higher in the second season than in the first
one. This difference may be due to changes in the
environmental conditions prevailing in both
seasons and /or other factors. In addition, the
data in Tables (1 and 2) showed that the ratio of
jassids and thirps population to each one of
tested predators population (0.03, 0.02, 0.02,
0.007) and (0.03, 0.02, 0.01, 0.006), (0.88,
0.54, 0.54, 0.19) and (0.78, 0.63, 0.38, 0.16)
Coccinella, Scymnus, Chrysoperla and Orius during seasons
2005 and 2006, respectively, were explain the
highest role of the tested predator in decrease
the population of jassids. On the other hand, the
lowest role of the tested predator in decreases
the population of thirps.
These observations are almost obtained by Mundhe
(1982), Bachatly (1984), Metwally (1989) and
Awadalla et al. (1991) stated that, one peak was
recorded in the population density of T. tabaci on
soybean during the growing seasons. Also, Mowafy
(1988), Metwally (1989) and Ali (1993) found that
8
the population of E. decipiens on soybean and broad
bean plants had only one peak.
In the same field Daiber (1994) mentioned
that the pods of green bean sown in spring or in
summer were attacked by thrips, Megalurothrips
sjostedti. Devesthali and Saran (1998) in India,
stated that pea thrips, Caliothrips indicus infesting
green gram, reached peak population density in
the fourth and fifth weeks of August. Wnuk and
Pobozniak (2003) stated that the population of T.
tabaci initially were Table (1): Mean number of Empoasca decipiens Paoli and
Thrips tabaci Lind. individuals and associated
predators per kidney bean leaf during summer
plantation (2005).
predat
ors
/leaf
Mean No. of predators/leafThrip
s/
leaf
Jassi
ds/
leaf
Sampling
ScheduleO.
albidipenn
is
C.
carne
a
S.
interruptu
s
C.undecimpunctat
a
0.270.010.040.100.120.251.40April 230.470.030.090.130.220.335.61300.560.050.150.130.230.377.75May 70.750.090.200.150.310.469.36140.610.080.150.140.240.319.11210.620.050.130.180.260.2913.28281.000.110.250.260.380.228.57June 40.730.040.220.170.300.198.0011
9
0.420.010.110.110.190.144,50180.170.000.030.060.080.051.2325
0.560.050.140.140.230.266.88
Mean/
leaf/
season
-0.0070.020.020.03--
Predator
/
jassids
-0.190.540.540.88--Predator
/ thrips
Table (2): Mean number of Empoasca decipiens Paoli and
Thrips tabaci Lind. individuals and associated predators
per kidney bean leaf during summer plantation (2006).
Predators
/leaf
Mean No. of predators/leafThrips/leaf
Jassids/leaf
SamplingSchedule
O.albidipenn
is
C.carne
a
S.interruptu
s
C.undecimpunctat
a
0.160.000.010.000.150.222.22April 22
10
0.830.070.200.230.330.279.7529
0.550.030.110.190.220.3511.80May 6
0.630.050.130.220.230.4313.6113
0.850.070.090.240.310.6513.3120
0.710.090.150.270.340.4914.5527
1.130.110.230.380.410.309.50June 3
0.800.080.140.260.320.246.2210
0.400.030.100.120.150.205.1217
0.210.010.020.100.080.091.7024
0.630.050.120.200.250.328.78Mean/leaf/season
-0.0060.010.020.03--Predator/
jassids-0.160.380.630.78--Predator
/ thrips
11
found on the leaves of pea plants, Pisum sativum
and as the pea was growing on the flower buds and
flowers.
El-Defrawi et al. (2000) found that the
common predators observed in faba bean fields
were Coccinella undecimpunctata L., Chrysoperla carnea
Steph, Syrphus corollae F., Phaenobremia aphidivora
Rubs. and Scymnus interruptus coeze. The minor
predators were Coccinella septempunctata L., Labidura
riparia Pall., Paederus alfierii Koch, Orius spp. and
certain spiders.
2. Effect of some climatic factors associated
some predators and plant age on the population
of E. decipiens and T. tabaci:
Tables (3 and 4) show the correlation between
the population density of E. decipiens, T. tabaci and
maximum, minimum temperature and maximum, minimum
relative humidity and plant age as well as the
associated predators during the two seasons of
2005 and 2006.
Data in the Table (3) indicated that,
considered climatic factors affected
insignificantly jassids population in the two
seasons. This means that the considered climatic
12
factors were within the optimal range for
population activity of jassids. Also, the plant
age affected insignificant on jassids population
during two seasons. On the other hand, the
predators had significant positive effect on
jassids population during first and second
seasons(r = 0.71 and 0.69, respectively). While,
the combined effect of four considered factors
(plant age, temperature, RH% and predators) on
jassids population was given as percentage of
explained variance (EV%) was cleared that, the
previous factors were responsible for 98.61 and
99.87% of variability in the population of E.
decipiens during first and second seasons,
respectively. But the plant age was responsible
for 87.76 and 95.41% of variability in the
population of jassids during first and second
seasons, respectively.
This means that, the plant age and predators
considered responsible factors for the influence
ratio on jassids population and there are other
unconsidered environmental factors responsible
for the remained ratio on jassid population.
These results contrast with finding of Abd El-
13
Fatah (1991) who found good relationship and
large effect of temperature, relative humidity on
population activity of E. decipiens on bean under
Egyptian condition. Singh et al. (1990) and
Jayanthi et al. (1993) found that the
environmental factors (temperature, RH%,
rainfall, wind speed and sunshine) affected the
population build up of Empoasca kerri on ground nut.
Our results showed that, the tested factors
(plant age, temperature, RH% and predators)
responsible for explained variance recorded
(98.61, 99.87%) during the two seasons on bean.
Data in the Table (4) indicated that, there
highly significant negative correlation between
the plant age and the population density of T.
tabaci during the first plantation season of 2005.
Also the data indicated that, the three negative
values of (r) increased gradually with increasing
in plant age (r = -0.74, -0.85 and -0.88,
respectively). In addition the highest negative
values at the last age of plant, this may be mean
that, when the plant directed to conform pods the
plant saps becomes unsuitable to T. tabaci. In the
closely meaning, the low negative amount of (r= -
14
0.74) in the age 1 of plant, this may be mean
when the plant directed to form chlorophyll and
green leaves, this condition is suitable for T.
tabaci. From previous must be condense the control
of T. tabaci at the early stage of bean. While the
minimum temperature produced significant negative
correlation (r = -0.66). However, the maximum
temperature, maximum and minimum relative
humidity and predators had no significant effect
on thrips population during 2005 season. It may
be means that, the population density of this
pest affected by the plant age and minimum
temperature than other tested factors. Concerning
the changes occurred in the population of T. tabaci
due to the change in plant age, the calculated
explained variance was 92.08% and equal 99.48% in
case of the combined effect of the tested
climatic factors and plant age and associated
predators. These values reflected that the
combined role of the climatic factors and
predators in influencing of the activity and
abundance of T. tabaci on bean plant was lower than
the role of the plant age.
15
In the second season of 2006, the calculated
correlation indicated significant negative with
the first and second plant ages(r= - 0.31 and -
0.49, respectively). While the other factors, had
no significant effect on thrips population during
this season. The total explained variance
percentages due to the plant age measured 76.94%,
while the combined effect of the all tested
factors measured 88.87%. From previously
mentioned, the population density of this pest
was affected by the plant age. This means that
there are other unconsidered environmental
factors responsible for the remained influence
ratio on thirps population.
The present results are in agreement with the
finding of Agostini and Muruaga (1990) and
Jarosik et al. (1997) reported that the population
density of thrips increased with time age of
common bean and cucumber plants and reached to
peak during the vegetative period before
fruiting. Plants were damaged from emergence
until pod formation. Booij (2003) stated that the
population dynamics of thrips T. tabaci on seven
crops dose not only depend on the weather factors
16
and the presence of the most susceptible crop but
is significantly affected by the interplay of
different sources at small and large scale.
Generally, it could be concluded that the
population of jassids, thrips and associated
predators were relatively higher during 2006
season than in 2005 season. The associated
predators play a role on jassid abundance.
�ٍ Table (3): Simple correlation and multiple regression coefficient of four factors on the population
density of Empoasca decipiens Paoli individuals on
kidney bean plants during summer plantation seasons of2005 and 2006.
Multipleregression
Simplecorrelation
andregression
FactorSeason
EV%EV%bbr
98.61
56.6-3.31
-21.15
-0.12Max. Temp.2005
-2.96
13.76
-0.09Min. Temp.
0.352.420.02Max. RH
1.41-7.96
0.12Min.RH
2.71-0.71*Predators
17
0.85
87.76121.32--0.04Age1
-10.96
--0.24
Age2
-0.02
--0.38Age3
99.87
89.02-4.18
17.26
-0.11Max. Temp.2006
-7.01
-3.84
-0.18Min. Temp.
3.76-3.41
0.13Max. RH
-12.06
-2.49
-0.59Min. RH
2.60.140.69*Predators
95.41256.11
--0.27Age1
-38.95
--0.47Age2
1.54--0.57Age3
*=Significant P< 0.05 **= Highly significant P< 0.01
18
�ٍ Table(4): Simple correlation and multiple regression coefficient of four factors on the population
density of Thrips tabaci Lind. individuals on Kidney
bean plants during summer plantation seasons of 2005 and 2006.
Multipleregression
Simplecorrelation
andregression
FactorSeason
EV%EV%bbr
99.48
62.87-1.993.47-0.58Max. Temp.
2005
-2.81
1.49-0.66*Min. Temp.
0.450.550.23Max. RH
0.200.630.13Min. RH
0.210.240.42Predators
92.08918.71
-0.74**Age1
-3.50
-0.85**
Age2
0.16-0.88**Age3
88.87
77.6425.11
29.69
-0.31*Max. Temp.2006
-3.42
-5.26
0.49*Min. Temp.
0.10.21-0.58Max. RH
19
-0.97
0.83-0.18Min. RH
-0.35
3.86-0.06Predators
76.940.08--0.02Age1
-1.08
--0.38Age2
0.24-0.45Age3
*=Significant P< 0.05 **= Highly significant P< 0.01
The plant age is an effective factor more
than the climatic factors in the population
density of E. decipiens and T. tabaci in bean plants.
The obvious relation between plant age
(considered as third degree of polynomial) and
studied pests dynamics can be attributed to
nutritional factors. These pests invade the
leaves which assumed to be the plant nutrient
provides. These leaves content of nutrient
(epically nitrogen compounds) is expected to
increase during the first third of plant age,
flattened in the flowering stage and decrease by
20
fruiting stage. For sure this relation is in
harmony with other environmental factors, which
also affects the studied pest's activity. That
may explain the higher contribution of plant age
on studied pest's densities than plan
environmental factors, which simulate the leaves
content of nitrogen compounds.
REFERENCES
Abd El-Fatah, S. M. (1991): Studies on insects
infesting Leguminous plants. M.Sc. Thesis,
Fac. Agric. Zagazg Univ.
Agostini, M. E. and A. S. Muruaga (1990):
Bioecological studies and damage produced by
thrips species (Thysanoptera : Thripidae)
found on crops of common bean (Phaseolus vulgaris
L. cv Alubia) in the Jujuy province
(Argentina). Revista de Investigacion Centro
de Investigaciones pora la Regulacion de
poblaciones de Organismos Nocivos, 8(1-4):57-
75.
Ali, F. I. (1993): Ecological studies on certain
insect pests of maize and soybean in
different soybean/maize intercropping
21
systems. Ph. D. Thesis, Fac. Agric. Al-Azhar
Univ.
Awadalla, S. S.; A.A. S. El-Zanan and R. M. Salem
(1991): Studies on injurious insects
infesting soybean plants and the efficiency
of certain chemicals against these pests at
Kafr El-Sheikh, Egypt. J. Agric. Soc.
Mansoura Univ. 16(2):420-429.
Bachatly, M. A. (1984): Ecological and biological
studies on soybean pests. M. Sc. Thesis, Fac.
Agric., Zagazig Univ.
Booij, K. (2003): Dynamics of Thrips tabaci in
diversified argo-ecosystems, a modeling
approach. Bull. OILB/SROP. 26 (4):19-24.
Chang, D. C. and C. C. Chen (1993): Population
fluctuation of major insect pests on kidney
bean and the proper time of control. Bull.
Taichung District Agric. Improvement Station.
38:11-22.
Daiber K. C. (1994): Injurious insects, spider
mites and nematodes on peas and green beans
in Southern Africa. Zeitschrift Fur
Pflanzenkrankheiten und Pflanzenchutz,
101:99-107.
22
Devesthali, S. and R.K. Saran (1998): Relative
susceptibility of new cultivars of green gram
(Vigna radiate L. Wilczek) to insect pests at
Indore (M.P.). Indian Agric. Res., 42
(4) :261-266 .
El-Defrawi, G. M.; A. K. Emam; I. A. Marzouk and
I. Rizkallah (2000): Population dynamics and
seasonal distribution of Aphis craccivora Koch
and associated natural enemies in relation to
virus disease incidence in faba bean fields.
J. Agric. Res., Egypt, 78(2):627-641.
El-Kifl, A. H.; A.E. A. Wahab; M. A. Assem and
A.A. Metwally (1974): List of insects, mites
and pests associated with leguminous crops in
Egypt. Bull. Soc. Ent. Egypt, 58: 297-302.
Fisher, R. A. (1950): Statistical methods for
research workers. II. Rev. Ed. Oliver and
Boyed, London.
Jarosik, V.; M. Kolias; L. lapchin; J. Rochat and
A.F.C. Dixon (1997): Seasonal trends in the
rate of population increase of Frankliniella
occidentalis (Thysanoptera:Thripidae) on
cucumber. Bull. Entomol. Res. 87(5):487-495.
23
Jayanthi, M.; K. M. Singh and R.N. Singh (1993):
Pests complex of high yielding groundnut
variety MH4 under Delhi conditions. Indian
J. Entomol. 55(1): 30-33.
Kogan, K. and D. C. Herzog (1980): Sampling
methods in soybean. Entomology, Springer-
Verlage New York.
Metwally, S. A. G. (1989): Ecological studies on
some insect pests infesting certain legume
crops in Qualyobia Governorate. Ph. D.
Thesis, Fac. Agric., Cairo Univ.
Mowafy, K. H. A. (1988): Studies on insect pests
attacking leguminous field crops in Egypt.
Ph. D. Thesis, Fac. Agric. Moshtoher, Benha
Branch, Zagazig Univ.
Mundhe, D. R. (1982): Studies on seasonal
incidence, screening of soybean cultivars and
chemical control against thrips (Coliothrips
indicus Bagnall). J. Maharashtra Agric. Univ.,
7:88-99.
Riudavets, J. (1995): Predators of Frankliniella
occidentalis (Preg) and Thirps tabaci Lind. A
Review Biological Control of Thrips Pests.
24
Wageningen Agricultural University Papers,
(1): 43-87.
Singh, T. V. K.; K. M. Singh and R. N. Singh
(1990): Groundnut, pest complex: IV-
Regression studies to determine the
association between jassid and thrips and
weather parameters. Indian J. Entomol. 52(4):
693-701.
Wnuk, A. and M. Pobozniak (2003): The occurrence
of thrips (Thripidae: Thysanoptera) on
different cultivars of pea (Pisum sativum L.).
J. Plant Protection Res., 43 (2) : 77-85.
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ة � ن6 ك ما اث ى� ك لأ ال موس مي� ل الي�رب �س ق� ى س ج� روة� واح دة� ق� د د� اس ي� و و 28ل لج� � دت� الkي�رب �س27 م أب kا احkم و ك � م أبى� دة� ق� kkروة� واح و و14د� � أب kkمى� 20 م kkوس لأل م � و ح � أب kkات�2006 و2005م kkي�رس ن6 ال مف� . ك مkkا ا والي� �kkت ع لى ال
وى� �kkعت ر م ي� �kkغ kًرا ي� ث�� أ � kkد ت ي� kkاس عkداد ال ج� � رk ت ي� ث�� أ � kkان6 ت kkوك . لأل م وس مى� ال دراسة� � و ح ت� � وي و وب�� � ى� م أب ن6 ق� ي� � روت ح دث �ت� د� اkرا ي� ث�� أ � kkد ت ي� kkاس عkkداد ال ج� � ات� ع لى ت kkي�رس رk ال مف� ي� ث�� أ � kkان6 ت kkا كkkم ي� ن¢ £ ن6 ت مي� kkموس ى� ال ات� ق� �kkي ة� و ع مkkر ال ن� � kkوث ل ال ج� kkعوام أل � ت
ن6 ى� ال موس مي� أ ق� � وت .م عت�
ة� ات� ال مصkاح ي�kي�رس ة� وال مف� � kوث ل ال ج� kعوام أل � وى� ت �kعت ر م ي� �kرًا غ ي� ث�� أ � kس ت� رة� الkي�رب عداد ح ش� � ر ت ي� ث�� أ � وك ان6 ت
ى� ًأ ق� � kkوت رًا م عت� ي� ث�� أ � kkس ت� رة� الkkي�رب �kkش عkkداد ح � رت� ع لى ت � kkت ات� ال حkkرارة� ال صkkغ�رى ا � kkدا درح kkا عkkم ي� � ن6 ق مي� kkموس ى� ال ق�
ن6 ع مkkkkر ى� ا �ي� ا ان� �kkkkي ول وال ى� ال موسkkkkم الأ أ ق� � kkkkوت رًا م عت� ي� ث�� أ � kkkkات� ت �kkkkي هkkkkر ع مkkkkر ال ن� ظ مkkkkا ا ي� ن¢ £ ول. ت ال موسkkkkم الأ
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ة� � kkوث ل ال ج� kkعوام عض� ال ب� £ ة� ي � kkارث د والkkي�رب �س م ف� ي� kkاس رة� ال ج� �kkش عkkداد ح � ر ع لى ت ي� °kkك رk الأ ي� ث�� ا �kkي كkkون6 لkkة ال � ات� ت �kkي ال ن�ة� ) سkkي� ن� � عkkداد ت ى� ال ب� ر ق� � kkت د ا � kkات� ق �kkي ن6 ع مkkر ال ن� ج6 ا اب� �kkي هkkرت� ال ن� ظ ت� ا ات� ح ي� kkي�رس 95.4 و 87.76وال مف�
راغة� 76.94 و92.8%( و) 1 لأل م وس مى� ال ر� � والي�2006 و2005%( ح ع لى ال ت�
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