In this study the effect of four types of plants diets (grass, sorghum, sesban and clover) on the changes in haemolymph protein and haemolymph protein profile of the adult desert locust Schistocerca gregaria (Forskal) and the susceptibility of locusts to Bacillus thuringiensis (Bt) have been investigated. The highest protein content was found in the haemolymph of locusts fed on clover and the lowest was found in insects fed on grass. In Bt injected locusts, there were significant decreased in the total haemolymph proteins at all the experimental diets compared with control insects except those fed on sorghum which showed insignificant differences with controls. The susceptibility of the locusts to Bt was the lowest, when fed on clover, while it was the highest in locusts fed on grass and an intermediate response was shown in locusts fed on sorghum or sesban. Analysis of proteins by SDS polyacrylamide gel electrophoresis showed disappearance of some protein bands and appearance of other new bands in the injected adults compared with controls. Some of these new proteins may affect adult immunity.

Key words: Schistocerca gregaria, Bacillus thuringiensis, plant diets, grass, clover, sorghum, sesban, haemolymph proteins and electrophoresis.