Ultrastructural effects of Celangulin V on midgut cells of the oriental armyworm, Mythimna separata walker (Lepidoptera: Noctuidae)

The ultrastructural effects of ingested Celangulin V (CA-V), an insecticidal component extracted from the root bark of Chinese bittersweet (Celastrus angulatus Maxim), on the midgut epithelial cells of the oriental armyworm larva (Mythimna separata Walker) were studied. Transmission electron microscopy showed that CA-V could induce a severe, time-dependent cytotoxicity of the midgut epithelial cells, which had large cytoplasmic spaces, disrupted microvilli and swollen mitochondria. The cisternae of the rough endoplasmic reticulum were excessively dilated, vesiculated and then fragmented. The nuclei were pycnotic and contained one or two divided nucleoli and agglomerated chromatin. Numerous lysosome-like vacuoles and secretion granules were observed. Finally, the CA-V resulted in cell death by necrosis with plasma membrane lysis and the cytoplasm content leakage into the migdut lumen.