Field Evaluation of Certain Pesticides Against the Cotton Bollworms with Special Reference to their...
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Field Evaluation of Certain Pesticides Against the Cotton Bollworms with Special
Reference to their Negative Impact on Beneficial Arthropods
(2006 cotton season, Minia region, Egypt)
Abdelrahman M. Younis,S.H. Hamouda, S.A. Ibrahim, and Z.A. Zeitoun
Plant Protection DepartmentFaculty of Agriculture
Minia UniversityMinia, Egypt
Introduction● In Egypt, about half a million feddans are
cultivated with cotton, representing 6% of all cultivated lands.
● Earias insulana and Pectinophora gossypiella are serious pests infecting cotton in Egypt.
● Economical yields are impossible to achieve without their chemical control.
● Chemical control of cotton pests costs 12.5 million U.S. dollars.
The pink bollworm Pectinophora gossypiella
larva adult
damaged cotton bolls
The spiny bollworm Earias insulana
damaged cotton boll
larva adult
Objectives● To select the most effective pesticides against
cotton bollworms.
● To study the indirect effect on seed cotton yield.
● To study the side effects on natural enemies.
Materials & Methods● Seven pesticides were evaluated.● Earias insulana and Pectinophora gossypiella.● Gossypium barbadens, (Giza 80 Cotton,
variety).● Cotton field was divided into 32 plots of 175 m2
each.● 100 green bolls/plot were collected for
recording the infestation and larval content before and after spray.
● Number of predators in each plot was monitored using a sweep net technique (Southwood, 1978).
● Reduction percentages were calculated (Henderson and Tilton, 1955).
● Seed cotton yield for each plot was weighed.
● Data was analyzed using analysis of variance (Gomez and Gomez, 1984).
Figure 1. %bollworms infestation
a
a
c
a
c
a
bc
a
c
b bc
a
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bc
b b
0
5
10
15
20
25
Pre-spray infestation Post-spray generalaverage of infestation
% In
fest
atio
n
Control g-cyhalothrin l-cyhalothrinesfenvalerate deltamethrin profenofoschlorpyrifos Bt-bioproduct
Figure 2. %Reduction in the bollworms infestation.
a a aab a
b
c
0102030405060708090
100
GATreatments
%R
educ
tion
in th
e in
fest
atio
n
g-cyhalothrin l-cyhalothrin esfenvalerate deltamethrin
profenofos chlorpyrifos Bt-bioproduct
Figure 3: larval content/100 green bolls
b
a
a
c
b
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ab
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abc c
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d0
1
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B-spray GA
Control g-cyhalothrin l-cyhalothrinesfenvalerate deltamethrin profenofoschlorpyrifos Bt-bioproduct
Figure 4. %Reduction in the general average of larval content
bbaabb
a
0102030405060708090
100
%R
educ
tion
Figure 5: Seed cotton yield (kentar/fed.)
c
bababaaaa
02468
1012141618
Seed
cot
ton
yiel
d (K
enta
r/fe
d.)
Figure 7. %Reduction in mean number of predators
b
c
abb
aaa
0
10
20
30
40
50
60
70
%Re
duct
ion
Conclusion● Synthetic pyrethroids exhibited the greatest
efficiency in controlling bollworms.
● The Bt-bioproduct was significantly the least effective treatment in reducing bollworm infestations.
● Seed cotton yield was greater in pyrethroid treatments > OP's ≥ Bt-bioproduct > control.
● The Bt-bioproduct resulted in the minimum negative impact toward beneficial arthropods.
● We suggest using gamma-cyhalothrin in rotation with the Bt-bioproduct to minimize the side effects on beneficials
Acknowledgements
● Financial support for this project was provided in part by the Ministry of Agriculture, Egypt.
● Financial support to participate and present this manuscript was provided in part by Minia University, Minia, Egypt.