Histological Effects of Emamectin Benzoate on Larvae of the Cotton Leaf Worm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae)

Histological effects for the LC50 of the bioinsecticide, emamectin benzoate on 4th instar larvae of the cotton leaf worm, Spodoptera littoralis (Boisd.) were studied. The tested bioagent induced several histological changes in the body wall (integument), midgut, fat bodies, malpighian tubules as well as muscles of the treated larvae after 72 hrs from treatment. It caused a separation of the hypodermis from the cuticle and degeneration of the hypodermal cells, Also, it causes severe damage to the ventricular (midgut) epithelium, detachment of the peritrophic and basement membranes from the epithelial cells of midgut, and degeneration of most its cells. Also, the tested bioinsecticide caused destruction of fat bodies, shrinkage and vacuolation of cytoplasm. In addition, most cells of malpighian tubules were degenerated and associated with nuclear clumped chromatin as rod-like compact mass. Muscles showed separation of fibrillae and disintegration of nuclei.