Toxicity and ultrastructural studies of thoracic muscles of Shistocerca gregaria (Forskal) treated with some insecticidal agents

Abstract

Experiments were conducted to evaluate the toxicity and histopathological effects on thoracic muscles of S. gregaria after treatment the 5th nymphal instar with different concentrations of IGR (Cascade), plant extract (Rice bran extract) and pyrethroid (Karate). The results indicated that all the concentrations of the tested compounds induced a positive effect on the percentage of nymphal mortality, while they caused a negative effect on the percentage of adult emergence. Moreover, the Rice bran extract showed the highest effect on the emergence of adults since (no adult emerged) at high concentration. Also, the ultrastructural study of thoracic muscles treated with the tested compounds showed disorganization of myofibrils, H, I and A bands became elongated, Z-line was not clearly defined. Some mitochondria were elongate, others were swollen with irregular and strange appearance and vacuoles appeared in the myofibrils.