The Effect of Some Bio-Insecticides on the Cotton Leaf Worm Spodoptera littoralis (Boisd.) Larvae

This study was conducted to investigate the effect of LC50concentration of three commercial bio insecticides; viruset, spodopetra littoralis nuclear polyhedrosis virus, protecto Bacillus thuringensisvar. kurstakiand their mixture profect on the protein profile and enzyme activity of three carbohydrate digestive enzymes (amylase, invertase and trehalase).The digestive enzymes were determined in 6th larva linstar after treatment of 3rd larval instar with the LC 50 concentration. Results showed that amylase activity was relatively un affected in treated larvae with viruset and protecto,but there was asignificant decrease when treated with profect compound.On the other hand the activity trehalase was significantly decreased in all samples. Also protein profile of the treated and untreated larvae was studied by SDS –PAGE technique. Results showed that the protein pattern of larvae treated with the profect compound leads to inhibition and appearance of some bands followed by protecto compound, while viruset has a slight change in the pattern. Thus, our findings indicated that among the three tested compounds, profect compound showed a highest significant effect on both protein profile and enzyme activity of the larvae.