ABSTRACT
Toxicity of two chemical insecticides chlorpyrifos, es-fenvalerate; a bioinsecticide (protecto); an IGR (lufenuron) and jojoba oil against 2nd and 4th larval instars of cotton leaf worm, Spodoptera litraltois (Boisd.) and the effect of these compounds on some biological characters and fecundity were studied on 4th instar larvae. Es-fenvalerate proved as the most effective insecticide against the 2nd and 4th instar larvae of S. littoralis after a feeding period 24hrs on treated leaves, followed by chlorpyrifos, lufenuron, jojoba oil and protecto. As for the efficiency of the tested insecticides against the 2nd instar larvae of S. littoralis, their LC50 values were 0.15, 0.17, 0.31, 4.61 ml/L and 16.64 gm/L, respectively. Prolongation in larval and pupal periods resulted from treated 4th instar larvae. The larval durations were 16.9, 14.1,13,7,12,1and14,1 days for lufenuron,chlorpyrifos, es-fenvalerate, protecto, and jojoba oil with the higher concentrations, respectively. In addition protecto, and jojoba oil, at lower concentrations showed an increase in pupation percentage, being 85.9% and 81.2%, respectively compared to 99.6% for control. The female fecundity and fertility showed significant reduction of the number of eggs deposited by each female developed from 4th larval instar treated with es-fenvalerate , lufenuron, protecto and jojoba oil compared with the control. The obtained data indicated also that the tested compounds caused failure of the insects’ embryonic development, showing the lower egg hatchability percentage comparison with control.
Key words: chlorpyrifos- es-fenvalerate- protecto- lufenuron - jojoba oil -Spodoptera littoralis
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