The proteolytic enzyme from midgut (epithelia and peri trophic membrane) of
the fifth instar larvae Spodoptera Iittoralis(Boisd.) is extracted and checked as crude
preparation with casein sodium as substrate .Also, the effect of (20%) extracts of
bestachia and dumb cane leaves on enzyme activity ,is studied. The protease activity is affected by different factors;e.g incubation period,
enzyme and substrate concentrations, pH number and starvation . The least activity
of the enzyme occurs at 40 min incubation period.The protease's found to be alkaline
as its optimum pH Is about(10).Starvation shows an abrupt Increase in enzyme
activity only for the first two hrs., then followed by a conUnious decrease in its activity. A significant Inhibition In the activities of protease,a'so OCCUI'$ when larvae
are fed on castor bean leaves treated with bestachia and dumb cane extracted in
methanol and hexane. There Is a poSitive correlation between both enzyme an~ substrate
concentrations and the enzyme protease activity.