Abstract
The present study was carried out to evaluate the susceptibility of the 4th larval instar of the cotton leaf worm Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) to some ripe fruit extracts of Melia azedarach and to study the biochemical activities of some enzymes in the pest under laboratory conditions. Contents of total carbohydrates and proteins were determined. The larvae, fed on M.azedarach oil or its terpenes treated leaves, recorded a decrease in the content of total carbohydrates and proteins compared with the control larvae. Activity of the enzymes glutamic pyruvic transaminase (GPT), glutamic transaminase oxaloacetic (GOT), alkaline phosphatase (ALK), invertase and amylase were decreased by 26.7, 19.73, 39.55, 23.20, 21.02% for oil and 43.93, 31.26, 63.64, 35.93, 20.52% for terpenes compared with the control 48 h post treatment. On the contrary, Alpha and beta estearses increased in the larvae, fed on the oil (48.20, 50.56%) or terpenes (38.4, 72.5%) treated leaves compared with the control larvae.