Nehad M. El-Barky

Humoral Immune Response And Midgut Histopatholical Changes In Grasshopper Schistocerca Gregaria Fed On Four Different Plants And Infected With Bacillus Thuringiensis

The present study investigated the effect of dietary changes on differential and total haemocyte counts (THCs) and midgut histopathologiocal changes of S. gregaria injected with Bacillus thuringiensis israelensis (Bti). THCs of Bti-injected adults significantly decreased in all insects fed on all experimental plants. In Bti-injected locusts, prohaemocytes (PRs) percent decreased in insects fed on grass and quietly disappeared in other treatments. plasmatocytes (PLs) percent increased, while the granulocytes (GRs) decreased in all tested insects fed on sorghum, sesban, grass and clover than those of the control. The percentages of oenocytoids (OEs) increased in all treatments except in insect fed on sesaban. The results indicated that insects fed on clover had the highest number of haemocytes, while those fed on grass had the lowest number. Certain pathological symptoms in the midgut of Bti treated adults were observed after 48 hr post injection, such as (1) disorganisation, disintegration and vacuolization of epithelial cells, (2) lysis of the basement membrane and surrounding muscles and (3) detachment of microvilli from epithelial cells. The most deformed group to Bti was grass fed locust. Subsequently, the host plant could be a major factor that affect on the response of herbivorous insects to pathogens.