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

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c

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0

5

10

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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

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0102030405060708090

100

GATreatments

%R

educ

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in th

e in

fest

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g-cyhalothrin l-cyhalothrin esfenvalerate deltamethrin

profenofos chlorpyrifos Bt-bioproduct

Figure 3: larval content/100 green bolls

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d0

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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.)

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bababaaaa

02468

1012141618

Seed

cot

ton

yiel

d (K

enta

r/fe

d.)

Figure 7. %Reduction in mean number of predators

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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.