EFFECT OF SOME NEW INSECTICIDES ON BIOLOGICAL AND BIOCHEMICAL CHANGES OF THE COTTON LEAFWORM, Spodoptera littoralis (Boisd.) (LEPIDOPTERA: NOCTUIDAE)

Abstract

The present study was carried out in an attempt to disclose the effect of three novel insecticides; Indoxacarb, Spinetoram and Methoxyfenozideon Spodoptera littoralis larvae under laboratory, field and semi-field conditions. The obtained data revealthat, Indoxacarb was the most toxic and effective insecticideon 2nd and 4th instar larvae ofS. littoralisfollowed by Spinetoram and Methoxyfenozide. The 2nd larval instars were more susceptible towards the tested insecticides than the 4th ones. The main components of insect metabolites, acetyl cholinesterase, alanine aminotransferase, aspartate aminotransferase and acid, alkaline phosphatase significantlyreduced due to larval treatment with the tested insecticides. Also, distinguishable patterns between control and treated samples were observed by the appearance and disappearance of certain protein fractions and differences in the activities of esterase isozymes. Field experiments proved that Indoxacarb was the best over Spinetoram and Methoxyfenozide in reducing number oflarvae of the tested pest on the data basis at zero time and tenth day from spraying. A gradual decrease in mortality rates of 2nd and 4th instar larvae of S. littoralis were obtained with time elapse since application under semi-field conditions. Keywords:Spodopteralittoralis - Indoxacarb- Spinetoram - Methoxyfenozide - protein electrophoresis - enzymes -esterasesisozymes -biochemical studies-field experiments.