The use of casein substrate gels for determining trypsin-like activity in the midgut of Glossina palpalis spp (Diptera: Glossinidae)

Trypsin-like activities in the midguts of Glossina palpalis spp red on different diets or exposed to 130 Gray γ-irradiation (Co60) were determined by measuring their casein-lytic activity in casein substrate gels. Proteases were only detected in the posterior midguts of the flies examined with generally higher levels in G.p. palpalis. The anterior midgut contained a subspecies specific inhibitor of trypsin-like activity. Peaks of protease activity occurred later and were lower in irradiated flies than in control flies. The significance of the casein method in determining midgut proteases of blood-feeding Diptera is described.