Efficacy of Certain Chemical and Bio-insecticides against Piercing-Sucking Pests, Cotton Leafworm and Associated Predators in Cotton Fields at Sharkia Governorate, Egypt

Document Type : Original Article

Authors

Plant Prot. Res. Inst., Agric. Res. Center, Dokki, Giza, Egypt

Abstract

Two experiments were conducted in cotton fields, Gossypium barbadense L. variety Giza 86 at Zagazig District, Sharkia Governorate, Egypt during 2013 and 2014 seasons to evaluate the efficacy of some chemical and bio-compounds against some cotton pests and its side effects on associated predators. In the first experiment, each of parathion-methyl, spinosad, azadirachtyin and dinotefuran compounds were tested at field only against the piercing-sucking pests (aphids,A.gossypii; whitefly,B. tabaci ; leafhoppers,Empoasca spp ; stink green bug,N. veridula and spider mites, Tetranychus spp.), associated predators and added Diple DF (Bacillus thuringiensis subsp. Kurstaki) in addition to the obvious compounds against cotton leafworm, S. littoralies . In the second experiment, each of parathion-methyl, spinosad, azadirachtyin, dinotefuran and B. thuringiensis)compounds were tested as field-laboratory technique to evaluate the latent effect of tested compounds on biological aspects of the second instar larvae of cotton leafworm.
The obtained results of the 1st experiment revealed that, the efficacy of tested compounds were varied as pests, seasons and time after application. The highest general mean effect of 81.85, 72.26 and 59.46% reduction were recorded for dinotefuran on aphids during the 1st season, on N. veridula during the 2nd one and on Tetranychus spp.during the 1st season, respectively. On the other hand, the highest general mean effect of 80.01 and 74.82 % reduction were recorded for parathion-methyl on B. tabaci and Empoasca spp during the 1st season, respectively. In case of S. littoralies the highest general mean effect of 75.91 % reduction were recorded for Parathion-methyl insecticide during 2014 season.
In regard to the side effects of tested compounds on predators associated with cotton pests, the dinotefuran insecticide recorded   highest general mean effect of 68.05 and 88.46 % reduction on lady bird beetles and true spider mites during the 2nd season, respectively. On the other hand, the parathion-methyl insecticide recorded highest general mean effect of 70.03, 71.88 and 68.11 % reduction on green lacewing, scmynus, and heave beetle during the 2nd season and 65.43 % on orius bug during the 1st season respectively.
The obtained results of biological effects of compounds tested as field-laboratory technique on the 2nd instar larvae of cotton leafworm revealed that, the highest mean of mortality of 86.67 %, longest larval duration of 12.25 days and lowest pupation percentage of 13.33 %   were recorded for larvae fed in laboratory on cotton leaves sprayed in field with parathion-methyl insecticide at zero time. The Btk compound decreased the pupal duration and shortest female longevity period compared with control and other tested compounds. Also, the lowest pupal weights of 0.2976 g/pupa and emergence percentage of 62.50 % were recorded for Btk compound. At the end, the lowest eggs number of 581.67 eggs/female was recorded for females emerged in parathion-methyl insecticide treatment at zero time. So, the Btk compound recorded good effect on S. littoralies biology followed by parathion-methyl insecticide.

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