ABSTRACT
This study highlights the complex relationship among the type of food, the performance of the locusts and mid gut proteins as well as the impact of bacterial infection on the midgut proteins of adult. Grasshopper nymphs supplied with different types of natural vegetation (grass, sorghum, sesban and clover) according to the seasons. S. gregaria fed on clover showed the highest growth rate and the largest mass and vice versa in grass fed locusts. The insects fed on grass (low protein diet) recorded the lowest midgut protein content while those fed on clover (high protein diet) recorded the highest midgut protein. The change in diet produced protein profiles differences among the feeding groups of S. gregaria adults. Insects fed on clover had many characteristic bands in protein profile of midgut and vice versa in case of feeding on grass.
After Bacillus thuringiensis israelensis (Bti) injection, Adults fed on clover showed the least susceptibility to Bti and vice versa in grass. Treated insects fed on clover had the highest midgut protein content while those fed on grass the lowest midgut protein content. Analysis of proteins midgut by SDS-polyacrylamide gel electrophoresis showed appearance of new bands in the injected adults compared to normal. In conclusion, this study emphasizes the close relationship between the type of food and the performance of the insect. It also confirms the impact of food and Bti infections on the midgut proteins. Therefore the important role of nutrition in insect immunity and response to diseases were studied.
Key words: Adult performance, Bacillus thuringiensis israelensis, Schistocerca gregaria, midgut protein profile, nutrition.
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