Biochemical studies of Bacillus Thuringiensis var.kurstaki, Serratia marcescns and Teflubenzurone on cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptea: Noctuidae)

Abstract

Two biopesticides Serratia marcescens [Eubacteriales: Enterobacteria] (used at MC 50 , concentration caused 50% malformation) and Bacillus thuringiensis Var. kurstaki (used at LC 50) and insect growth regulator Teflubenzuron (used at LC 50 value) were used for treatment of 2 nd instar larvae of cotton leafworm, Spodoptera littoralis (Boisd.). Sequential combined Effect was carried out by treating 2 nd instar larvae with LC 50 value of B. thuringiensis or Teflubenzuron then the larvae allowed to pupate on sawdust treated with S. marcescens at MC 50 .The effect of these three agents were assessed by toxicity The obtained LC 50 values were 0.113 and 165.64 ppm, for Teflubenzuron and B. thuringiensis Var. kurstaki. (protecto), respectively. Moreover, the activity of Chitinase, protease, trehalase, and the main components (total lipids, proteins and carbohydrates) were significantly fluctuated during the different periods of pupal stage. MATERIALS AND METHODS Rearing technique The stock culture of the cotton leafworm, S. littoralis (Boisd.) was El-Sheikh, T. A. A. et al.